Bowel Stiffness Assessed by Shear-Wave Ultrasound Elastography Predicts Disease Behavior Progression in Patients With Crohn's Disease.

INTRODUCTION: There is a lack of reliable predictors of disease behavior progression in patients with Crohn's disease (CD). Real-time shear-wave elastography (SWE) is a novel method for evaluating tissue stiffness. However, its value for assessing CD has not yet been investigated. We aimed to explore the value of SWE and other ultrasound parameters at diagnosis in predicting CD behavior progression. METHODS: We retrospectively collected data from patients with CD with the nonstenotic nonpenetrating disease (B1 phenotype based on the Montreal classification). All patients underwent intestinal ultrasound at baseline and were followed up. The end point was defined as disease behavior progression to stricturing (B2) or penetrating (B3) disease. Cox regression analysis was performed for the association between baseline characteristics and subsequent end points. In addition, a multivariate nomogram was established to predict the risk of disease behavior progression quantitatively. RESULTS: A total of 130 patients with CD with B1 phenotype were enrolled. Twenty-seven patients (20.8%) developed B2 or B3 disease, with a median follow-up of 33 months. Multivariate analysis identified that SWE was the only independent predictor of disease behavior progression (hazard ratio 1.08, 95% confidence interval 1.03-1.12, P = 0.001). A reverse of the HR appeared at the cutoff 12.75 kPa. The nomogram incorporating SWE and other clinical characteristics showed a good prediction performance (area under the curve = 0.792). DISCUSSION: Intestinal stiffness assessed using SWE is an independent predictor of disease behavior progression in patients with CD. Patients with CD with SWE >12.75 kPa at diagnosis are prone to progress toward stricturing or penetrating diseases.

Left Ventricular Pressure Strain Loops for Evaluation of Myocardial Work in Type 2 Diabetic Patients with Hypertension.

BACKGROUND: Type 2 diabetes mellitus (T2DM) and hypertension (HT) are the two most common underlying diseases worldwide, and they often coexist. The long-term existence of both may lead to left ventricular dysfunction. Therefore, evaluating the cardiac function of T2DM patients with HT is vital to guide treatment and improve prognosis. Left ventricular pressure strain loops (LVPSL) combine left ventricular strain and afterload, which can quantify left ventricular energy expenditure and detect left ventricular subclinical systolic dysfunction. Many studies have focused on myocardial work (MW) in uncomplicated T2DM patients or simple HT patients, but a few have focused on T2DM patients with HT. OBJECTIVE: The study aimed to evaluate the MW changes in T2DM patients with HT using LVPSL and to find independent related factors of MW parameters. METHODS: 40 T2DM patients, 35 HT patients, 40 T2DM patients with HT (T2DM+HT group), and 35 controls were enrolled. The differences between clinical data, conventional ultrasound parameters, and MW parameters were analyzed among the four groups. RESULTS: The global longitudinal strain (GLS) of the T2DM group, HT group, and T2DM+HT group was lower than the control group (P<0.05). The global work index (GWI) and global constructive work (GCW) in the T2DM group were lower than other groups (P<0.05). The GWI of the HT group was higher than other groups (P<0.05), while GCW was only higher than the T2DM group and T2DM+HT group (P<0.05). The GWI and GCW of the T2DM+HT group were higher than the T2DM group and were lower than the HT group(P<0.05), while there was no significant difference with the control group. HT group and T2DM+HT group had higher global work waste (GWW) (P<0.05). The global work efficiency (GWE) of the T2DM+HT group was lower than other groups (P<0.05). Systolic blood pressure (SBP) and glycosylated hemoglobin (HbA1c) were independent factors of each MW parameter. CONCLUSION: LVPSL can recognize left ventricular subclinical systolic dysfunction early in patients with T2DM and HT. Compared to simple T2DM or HT, the combination of T2DM and HT had greater damage to left ventricular systolic function. SBP and HbA1c are two factors that have a considerable impact on MW parameters. The impact of afterload on MW parameters should be paid more attention to.

Color-Tunable Binary Copolymers Manipulated by Intramolecular Aggregation and Hydrogen Bonding.

Construction of color-tunable luminescent polymeric materials with enhanced emission intensity and room-temperature phosphorescence (RTP) performance regulated by a single chromophore component is highly desirable in the scope of photoluminescent materials. Herein, a set of binary copolymers were facilely synthesized using free radical polymerization by selecting different types of polymer matrix and N-substituted naphthalimides (NPA) as chromophores. Surprisingly, the fluorescence emission of copolymers could be remarkably enhanced, because of the intramolecular aggregation of NPA manipulated by a single polymer chain in both solution and solid state. Moreover, RTP signals of binary copolymers were all clearly observed in the air without any processing procedure, because of the embedding of phosphors into hydrogen bonding networks after copolymerization with vinyl-based acrylamide monomers. Taking advantages of the synergistic effect of copolymerization-induced aggregation and copolymerization-induced rigidification to promote optical performance, UV stimulus-responsive luminescent polymer films with processability, flexibility, and adjustable emission wavelength were simply prepared using a drop-casting method in large scale, the setting of which is the basis for application in the fields of organic optoelectronics, information security, and bioimaging/sensing.

Tale of COF-on-MOF Composites with Structural Regulation and Stepwise Luminescence Enhancement.

Integrating metal-organic framework (MOF)-covalent organic framework (COF) allows versatile engineering of hybrid materials with properties superior to pristine components, especially COFs suffered from aggregation-caused quenching (ACQ), unlocking more possibilities to improve the luminescence of COFs. In this work, we prepared various MOF@COF composites with different COF layer thicknesses, in which stable UiO-66-NH2 served as the inner substrate and 1,3,5-benzenetricarboxaldehyde (BT), and 3,3'-dihydroxybenzidine (DH) were used to construct a COF layer. In addition to the conventional preparation method, we increased the ratio of BT and DH to be 1:2.5, and impressively, the morphologies of acquired UC (1:2.5) materials were quite different from the previous reticular structure and gradually extended from the spherical structure to the prickly structure with the increase of COF monomers. Remarkably, all of the UC materials possessed better luminescence properties than individual COF due to the limited COF layers. Meanwhile, UC-1 materials with an optimal COF layer displayed the strongest emission. In comparison with a single COF, the quantum yields of UC-1 and UC-1 (1:2.5) were increased nearly 7 times and 5 times, respectively. Moreover, the fluorescence of UC-1 materials was progressively enhanced via selective F- sensing. This work is expected to shed light on the potential hybridization of MOF-COF with structural adjustment, morphological design, and luminescence enhancement.

Tunable fluorescence emission based on multi-layered MOF-on-MOF.

Luminescent metal-organic frameworks (MOFs) have garnered considerable attention in various fields. Herein, we proposed a hierarchical confinement strategy based on MOF-on-MOF to tune luminescence emission ranging from blue to red including white light in a flexible way. The easily available ZIF-8 MOF was used as a host for the confinement of two kinds of size-matching dyes (perylene and rhodamine B) to obtain a layered ZIF-8@dye@ZIF-8@dye via in situ encapsulation and seed-mediated synthesis. ZIF-8@dye@ZIF-8@dye materials with different fluorescence emission in dispersed and solid states were both obtained by tuning the initial encapsulation concentration of dye and changing the structure of the inner and outer ZIF-8@dye layers. To our delight, ZIF-8@0.125perylene@ZIF-8@25RhB with white light emission in the dispersed state was obtained; meanwhile, ZIF-8@0.125perylene + 25RhB and mechanically mixed ZIF-8@0.125perylene + ZIF-8@25RhB could not realize white light emission under the same conditions, indicating that the proposed hierarchical confinement strategy facilitated white light regulation. Similarly, the emission of ZIF-8@dye@ZIF-8@dye in the solid state has also been investigated; ZIF-8@perylene@ZIF-8@3RhB with white light emission was obtained, while white light emission could not be achieved in ZIF-8@perylene + 3RhB and ZIF-8@perylene + ZIF-8@3RhB, which further indicated the importance of the hierarchical confinement strategy based on MOF-on-MOF. The proposed hierarchical confinement strategy may also inspire the development of other functional optical MOF materials.

Application of Contrast-enhanced Ultrasound and Bosniak Classification to the Diagnosis of Cystic Renal Masses.

BACKGROUND: The Bosniak classification system based on contrast-enhanced computed tomography (CECT) is commonly used for the differential diagnosis of cystic renal masses. Contrastenhanced ultrasound (CEUS) is a relatively novel technique, which has gradually played an important role in the diagnosis of cystic renal cell carcinoma (CRCC) due to its safety and lowest price. OBJECTIVE: The aim of the study is to investigate the application value of CEUS and Bosniak classification into the diagnosis of cystic renal masses. METHODS: 32 cystic masses from January 2018 to December 2019 were selected. The images of conventional ultrasound (US), CEUS and CECT from subjects confirmed by surgical pathology were retrospectively analyzed. The Bosniak classification system of cystic renal masses was implemented using CEUS and CECT, and the diagnostic ability was compared. RESULTS: For the 32 cystic masses, postoperative pathology confirmed 11 cases of multilocular CRCC, 15 cases of clear cell carcinoma with hemorrhage, necrosis and cystic degeneration, 5 cases of renal cysts, and 1 case of renal tuberculosis. The Bosniak classification based on CEUS was higher than that based on CECT, and the difference was statistically significant (P = .024). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CEUS were comparable to CECT. There was no significant difference observed in the diagnosis of CRCC (P >.05). CONCLUSION: CEUS combined with Bosniak classification greatly improves the diagnosis of CRCC. CEUS shows a comparable diagnostic ability to CECT. In daily clinical routine, patients who require multiple examinations and present contraindications for CECT can particularly benefit from CEUS.

Construction and Sensing Amplification of Raspberry-Shaped MOF@MOF.

MOFs@MOFs (metal-organic frameworks, MOFs) possess precise customized functionalities and predesigned structures that enable the implementation of structure and property regulation for specific functions in comparison to traditional single MOFs. However, the synthesis and fluorescence properties of multilayer MOFs@MOFs are still worth improving. Herein, a fluorescent raspberry-shaped MOF@MOF was constructed via optimized seed-mediated synthesis by tuning the reaction time, reaction mode, and reaction concentration, involving the initial synthesis of the UiO-66-NH2 core and then the coating of the UiO-67-bpy shell. The raspberry-shaped UiO-66@67-bpy showed stable fluorescence and desirable sensing selectivity for the Hg2+ ion under the interference of other ions; meanwhile, the raspberry-shaped UiO-66@67-bpy indicated amplified sensing performance than pure UiO-66-NH2, mechanically mixed UiO-66-NH2 + UiO-67-bpy, and UiO-66@UiO-67 counterpart due to the accumulation effect of outer UiO-67-bpy toward Hg2+. Density functional theory (DFT) calculations including adsorption energy calculations and electronic density difference analysis further showed that the enhanced fluorescence quenching was possibly attributed to the outer UiO-67-bpy enrichment promoting the charge transfer between Hg2+ and the ligands of fluorescent UiO-66@67-bpy. The synergistic effect of MOFs@MOFs unlocks more possibilities for the construction of enhanced sensors and other applications.

Longitudinal Bowel Behavior Assessed by Bowel Ultrasound to Predict Early Response to Anti-TNF Therapy in Patients With Crohn's Disease: A Pilot Study.

BACKGROUND: Early changes in bowel behavior during anti-tumor necrosis factor (anti-TNF) induction therapy in Crohn's disease (CD) are relatively unknown. We determined (1) the onset of changes in bowel behavior in CD patients receiving anti-TNF therapy by ultrasound and (2) the feasibility of shear wave elastography (SWE) in predicting early response to anti-TNF therapy. METHODS: Consecutive ileal or ileocolonic CD patients programmed to initiate anti-TNF therapy were enrolled. Bowel ultrasound was performed at baseline and at weeks 2, 6, and 14. Changes in bowel wall thickness, Doppler signals of the bowel wall (Limberg score), and SWE values were compared using a linear mixed model. Early response to anti-TNF therapy was based on a composite strategy of clinical and colonoscopy assessment at week 14. RESULTS: Of the 30 patients enrolled in this study, 20 patients achieved a response to anti-TNF therapy at week 14. The bowel wall thickness and SWE value of the response group showed a significant downward trend compared with the nonresponse group (P = .003 and P = .011, respectively). Bowel wall thickness, the Limberg score, and SWE values were significantly reduced as early as week 2 compared with baseline (P < .001, P < .001, and P = .003, respectively) in the response group. Baseline SWE values (21.3 ± 8.7 kPa vs 15.3 ± 4.7 kPa; P = .022) and bowel wall thickness (8.5 ± 2.3 mm vs 6.9 ± 1.5 mm; P = .027) in the nonresponse group were significantly higher than in the response group. CONCLUSIONS: This pilot study suggested that changes in bowel ultrasound behavior could be assessed as early as week 2 after starting anti-TNF therapy. Bowel ultrasound together with elasticity imaging could predict early response to anti-TNF therapy.

This pilot study suggested that changes in bowel ultrasound behavior could be assessed as early as 2 weeks after anti-tumor necrosis factor therapy in patients with Crohn's disease. Bowel ultrasound together with elasticity imaging could predict early response to anti-tumor necrosis factor therapy.

All-trans-retinoic acid generation is an antidotal clearance pathway for all-trans-retinal in the retina.

The present study was designed to analyze the metabolites of all-trans-retinal (atRal) and compare the cytotoxicity of atRal versus its derivative all-trans-retinoic acid (atRA) in human retinal pigment epithelial (RPE) cells. We confirmed that atRA was produced in normal pig neural retina and RPE. The amount of all-trans-retinol (atROL) converted from atRal was about 2.7 times that of atRal-derived atRA after incubating RPE cells with 10 µmol/L atRal for 24 h, whereas atRA in medium supernatant is more plentiful (91 vs. 29 pmol/mL), suggesting that atRA conversion facilitates elimination of excess atRal in the retina. Moreover, we found that mRNA expression of retinoic acid-specific hydroxylase CYP26b1 was dose-dependently up-regulated by atRal exposure in RPE cells, indicating that atRA inactivation may be also initiated in atRal-accumulated RPE cells. Our data show that atRA-caused viability inhibition was evidently reduced compared with the equal concentration of its precursor atRal. Excess accumulation of atRal provoked intracellular reactive oxygen species (ROS) overproduction, heme oxygenase-1 (HO-1) expression, and increased cleaved poly(ADP-ribose) polymerase 1 (PARP1) expression in RPE cells. In contrast, comparable dosage of atRA-induced oxidative stress was much weaker, and it could not activate apoptosis in RPE cells. These results suggest that atRA generation is an antidotal metabolism pathway for atRal in the retina. Moreover, we found that in the eyes of ABCA4-/-RDH8-/- mice, a mouse model with atRal accumulation in the retina, the atRA content was almost the same as that in the wild type. It is possible that atRal accumulation simultaneously and equally promotes atRA synthesis and clearance in eyes of ABCA4-/-RDH8-/- mice, thus inhibiting the further increase of atRA in the retina. Our present study provides further insights into atRal clearance in the retina.

Arctigenin prevents monocrotaline-induced pulmonary arterial hypertension in rats.

The hallmark features of the development of pulmonary arterial hypertension (PAH) include the proliferation of pulmonary vascular smooth muscle cells, oxidative stress, inflammation, and pulmonary artery remodeling. Arctigenin is a bioactive component of Arctium lappa that exerts anti-inflammatory and antiproliferative effects in several diseases; however, its effects on pulmonary arteries are still unclear. This study aimed to investigate the efficacy of arctigenin to prevent PAH. Rats injected with monocrotaline (MCT) progressively developed PAH. Arctigenin treatment (50 mg per kg per day, intra-peritoneally) ameliorated right ventricular systolic pressure and pulmonary arterial remodeling, decreased the expression of inflammatory cytokines, and limited the proliferation of pulmonary vascular smooth muscle cells in lungs. Mechanistically, arctigenin effectively inhibited the MCT-induced elevation of NLRP3, caspase-1, and interleukin 1-beta expression in the lungs. These results indicate that arctigenin ameliorates MCT-induced PAH, at least in part, through exerting its anti-inflammatory, antioxidant, and antiproliferative effects, which inhibit the NLRP3 inflammasome signal pathway in rats.

Growing Platinum-Ruthenium-Tin ternary alloy nanoparticles on reduced graphene oxide for strong ligand effect toward enhanced ethanol oxidation reaction.

Uniform Pt1Ru0.5Sn0.5 ternary alloy nanoparticles are in situ deposited on reduced graphene oxide (Pt1Ru0.5Sn0.5-RGO) through its functional groups and defects as nucleation sites to greatly electrocatalyze ethanol oxidation reaction for much higher mass current densities, larger apparent specific current densities and better stability than commercial Pt-C catalyst (Pt-C(commer)). Mechanistic studies indicate that the excellent electrocatalytic activity and anti-poisoning are resulted from a strong ligand effect of the ternary alloy components, in which the charge transfer is boosted while decreasing the density of states close to the Fermi level of Pt to reduce bond energy between Pt and CO-like adsorbates for greatly improved anti-poisoning ability. This work holds a great promise to fabricate a high performance anode catalyst with a low Pt loading for direct ethanol fuel cells.

Vitamin D Supplementation in the Treatment of Chronic Heart Failure: A Meta-analysis of Randomized Controlled Trials.

BACKGROUND: In recent years, there has been growing evidence that vitamin D deficiency is associated with the development and progression of chronic heart failure (CHF). HYPOTHESIS: Additional supplementation of vitamin D may have protective effects in patients with CHF. METHODS: We searched PubMed, Embase, and Cochrane databases through June 2015 and included 7 randomized controlled trials that investigated the effects of vitamin D on cardiovascular outcomes in patients with CHF. Then, we performed a meta-analysis of clinical trials to confirm whether vitamin D supplementation is beneficial in CHF patients. The weighted mean difference (WMD) and 95% confidence interval (CI) were calculated using fixed- or random-effects models. RESULTS: Our pooled results indicated that additional supplementation of vitamin D was not superior to conventional treatment in terms of left ventricular ejection fraction, N-terminal pro-B-type natriuretic peptide, and 6-minute walk distance. Moreover, vitamin D supplementation was associated with significant decreases in the levels of tumor necrosis factor-α (WMD: -2.42 pg/mL, 95% CI: -4.26 to -0.57, P < 0.05), C-reactive protein (WMD: -0.72 mg/L, 95% CI: -1.42 to -0.02, P < 0.05), and parathyroid hormone (WMD: -13.44 pg/mL, 95% CI: -21.22 to -5.67, P < 0.05). CONCLUSIONS: Vitamin D supplementation may decrease serum levels of parathyroid hormone and inflammatory mediators in CHF patients, whereas it has no beneficial effects on improvement of left ventricular function and exercise tolerance.

Long non-coding RNA PVT1 as a novel biomarker for diagnosis and prognosis of non-small cell lung cancer.

Accumulating evidence has indicated that long non-coding RNA PVT1 is upregulated in various human cancers. However, it remains unclear whether PVT1 is involved in the development and progression of non-small cell lung cancer (NSCLC). The present study was designed to investigate the expression, biological role, and clinical significance of PVT1 in NSCLC. Our results indicated that PVT1 expression was significantly increased in NSCLC tissues and cell lines, and its upregulation was associated with advanced T-stage and tumor-node-metastasis (TNM) stage and regional lymph node metastasis. PVT1 expression levels were robust in differentiating NSCLC tissues from controls. Kaplan-Meier curve and Cox regression analysis showed that high expression of PVT1 was associated with poor overall survival and disease-free survival in NSCLC patients. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays indicated that knockdown of PVT1 remarkably inhibited NSCLC cell proliferation, whereas overexpression of PVT1 significantly promoted cellular proliferation. In addition, PVT1 knockdown increased the number of cells in the G0/G1 phase and reduced the number of cells in the S phase, while overexpression of PVT1 could promote cell cycle progression. Furthermore, our findings also revealed that the messenger RNA (mRNA) and protein expression of P15 and P21 was significantly upregulated in NSCLC cells transfected with PVT1 small interfering RNA (siRNA) and downregulated in cells transfected with pcDNA3.1-PVT1. In conclusion, our study demonstrated that PVT1 might serve as a promising biomarker for diagnosis and prognosis of NSCLC, and it could promote the proliferation of NSCLC cells by downregulating p15 and p21 expression.

Identification and Characterization of CYP9A40 from the Tobacco Cutworm Moth (Spodoptera litura), a Cytochrome P450 Gene Induced by Plant Allelochemicals and Insecticides.

Cytochrome P450 monooxygenases (P450s) of insects play crucial roles in the metabolism of endogenous and dietary compounds. Tobacco cutworm moth (Spodoptera litura), an important agricultural pest, causes severe yield losses in many crops. In this study, we identified CYP9A40, a novel P450 gene of S. litura, and investigated its expression profile and potential role in detoxification of plant allelochemicals and insecticides. The cDNA contains an open reading frame encoding 529 amino acid residues. CYP9A40 transcripts were found to be accumulated during various development stages of S. litura and were highest in fifth and sixth instar larvae. CYP9A40 was mainly expressed in the midgut and fat body. Larval consumption of xenobiotics, namely plant allelochemicals (quercetin and cinnamic acid) and insecticides (deltamethrin and methoxyfenozide) induced accumulation of CYP9A40 transcripts in the midgut and fat body. Injection of dsCYP9A40 (silencing of CYP9A40 by RNA interference) significantly increased the susceptibility of S. litura larvae to the tested plant allelochemicals and insecticides. These results indicate that CYP9A40 expression in S. litura is related to consumption of xenobiotics and suggest that CYP9A40 is involved in detoxification of these compounds.

MicroRNA-19a regulates lipopolysaccharide-induced endothelial cell apoptosis through modulation of apoptosis signal-regulating kinase 1 expression.

BACKGROUND: MicroRNAs, small non-encoding RNAs that post-transcriptionally modulate expression of their target genes, have been implicated as critical regulatory molecules in endothelial cells. RESULTS: In the present study, we found that overexpression of miR-19a protects endothelial cells from lipopolysaccharide (LPS)-induced apoptosis through the apoptosis signal-regulating kinase 1 (ASK1)/p38 pathway. Quantitative real-time PCR demonstrated that the expression of miR-19a in endothelial cell was markedly down-regulated by LPS stimulation. Furthermore, LPS-induced apoptosis was significantly inhibited by over-expression of miR-19a. Finally, both a luciferase reporter assay and western blot analysis showed that ASK1 is a direct target of miR-19a. CONCLUSIONS: MiR-19a regulates ASK1 expression by targeting specific binding sites in the 3' untranslated region of ASK1 mRNA. Overexpression of miR-19a is an effective method to protect against LPS-induced apoptosis of endothelial cells.

A novel cytochrome P450 CYP6AB14 gene in Spodoptera litura (Lepidoptera: Noctuidae) and its potential role in plant allelochemical detoxification.

Cytochrome P450 monooxygenases (P450s) play a prominent role in the adaptation of insects to host plant chemical defenses. To investigate the potential role of P450s in adaptation of the lepidopteran pest Spodoptera litura to host plant allelochemicals, an expressed sequence data set derived from 6th instar midgut tissues was first mined. One sequence identified from the S. litura 6th instar midgut EST database was determined by phylogenetic analysis to belong to the CYP6AB P450 subfamily, and named CYP6AB14. Dietary supplementation of S. litura larvae with either xanthotoxin (XAN), coumarin (COU) and flavone (FLA) led to elevated CYP6AB14 transcript levels in both midgut and fat body tissues. Injection of CYP6AB14-derived double-stranded RNA (dsRNA) into S. litura individuals significantly reduced CYP6AB14 transcript levels, and resulted in increased developmental abnormalities and higher mortality rates among XAN, COU and FLA-fed larvae. Our results strongly suggest a key role for CYP6AB14 in plant allelochemical detoxification in S. litura.

Molecular characteristics of Salmonella genomic island 1 in Proteus mirabilis isolates from poultry farms in China.

Six out of the 64 studied Proteus mirabilis isolates from 11 poultry farms in China contained Salmonella genomic island 1 (SGI1). PCR mapping showed that the complete nucleotide sequences of SGI1s ranged from 33.2 to 42.5 kb. Three novel variants, SGI1-W, SGI1-X, and SGI1-Y, have been characterized. Resistance genes lnuF, dfrA25, and qnrB2 were identified in SGI1 for the first time.

Dynamics of quinolone resistance in fecal Escherichia coli of finishing pigs after ciprofloxacin administration.

Escherichia coli resistance to quinolones has now become a serious issue in large-scale pig farms of China. It is necessary to study the dynamics of quinolone resistance in fecal Escherichia coli of pigs after antimicrobial administration. Here, we present the hypothesis that the emergence of resistance in pigs requires drug accumulation for 7 days or more. To test this hypothesis, 26 pigs (90 days old, about 30 kg) not fed any antimicrobial after weaning were selected and divided into 2 equal groups: the experimental (EP) group and control (CP) group. Pigs in the EP group were orally treated daily with 5 mg ciprofloxacin/kg of body weight for 30 days, and pigs in the CP group were fed a normal diet. Fresh feces were collected at 16 time points from day 0 to day 61. At each time point, ten E. coli clones were tested for susceptibility to quinolones and mutations of gyrA and parC. The results showed that the minimal inhibitory concentration (MIC) for ciprofloxacin increased 16-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin administration for 3 days and decreased 256-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin withdrawal for 26 days. GyrA (S83L, D87N/ D87Y) and parC (S80I) substitutions were observed in all quinolone-resistant E. coli (QREC) clones with an MIC ≥8 µg/ml. This study provides scientific theoretical guidance for the rational use of antimicrobials and the control of bacterial resistance.