APNet: Adaptive projection network for medical image denoising.

BACKGROUND: In clinical medicine, low-dose radiographic image noise reduces the quality of the detected image features and may have a negative impact on disease diagnosis. OBJECTIVE: In this study, Adaptive Projection Network (APNet) is proposed to reduce noise from low-dose medical images. METHODS: APNet is developed based on an architecture of the U-shaped network to capture multi-scale data and achieve end-to-end image denoising. To adaptively calibrate important features during information transmission, a residual block of the dual attention method throughout the encoding and decoding phases is integrated. A non-local attention module to separate the noise and texture of the image details by using image adaptive projection during the feature fusion. RESULTS: To verify the effectiveness of APNet, experiments on lung CT images with synthetic noise are performed, and the results demonstrate that the proposed approach outperforms recent methods in both quantitative index and visual quality. In addition, the denoising experiment on the dental CT image is also carried out and it verifies that the network has a certain generalization. CONCLUSIONS: The proposed APNet is an effective method that can reduce image noise and preserve the required image details in low-dose radiographic images.

[The correlation analysis on Enterococcus faecalis biofilm and clinical manifestation in retreatment of root canal].

OBJECTIVE: To detect the ability of Enterococcus faecalis (E. faecalis) biofilm formation and explore the relationship between E. faecalis biofilm formation ability and clinical manifestation. METHODS: 96 well plate with the establishment of 53 E. faecalis in vitro biofilm model, combined with crystal violet staining, was used to test the biofilm formation ability of the clinical isolates E. faecalis and analyze the relationship between biofilm formation capacity and clinical manifestation. RESULTS: In total 53 E. faecalis strains, 40 strains(75.47%) had biofilm forming ability. Statistical analysis revealed that the capacities of biofilm formation between E. faecalis isolated from with fistula and without fistula was significantly different (P<0.05). CONCLUSION: In the retreatment of root canal, the ability of biofilm formation of E. faecalis separated from the teeth without fistula is better than those separated from the teeth with fistula.

Relationship of biofilm formation and gelE gene expression in Enterococcus faecalis recovered from root canals in patients requiring endodontic retreatment.

INTRODUCTION: Enterococcus faecalis is known to be the most frequently detected species in root canals with failed endodontic treatment. Many studies are available on biofilm formation and the expression of virulence factors such as gelatinase (gelE) in E. faecalis. However, the relationship of biofilm formation and the expression of gelE in E. faecalis recovered from root canals undergoing orthograde retreatment is not well understood. METHODS: E. faecalis was isolated from clinical samples of root canal retreatment, and the expression of gelE in E. faecalis was assessed. Automatic microplate reader and scanning electron microscopy were used to investigate the biofilm formation ability of E. faecalis isolates. Real-time quantitative polymerase chain reaction was used for detecting the expression of gelE in biofilm-positive and biofilm-negative E. faecalis isolates. RESULTS: The detection rate of E. faecalis in the root canal retreatment cases was 39.26%. An automatic microplate reader showed that most isolates were able to form biofilms, and the biofilm formation ability of strains isolated from the teeth without a sinus tract was better than that with a sinus tract (P < .05). The expression of gelE was stronger in the cases of apical radiolucency than in those without the symptom (P < .05). The expression of gelE was higher in the biofilm-positive than in biofilm-negative strains (P < .05). CONCLUSIONS: Biofilm formation in E. faecalis was facilitated in the cases without a sinus tract. In the cases of apical radiolucency and in the biofilm-positive strains, the expression of gelE was higher.

[Analysis of relationship between the detection of Enterococcus faecalis in post-treatment endodontic disease and clinical symptom or sign].

OBJECTIVE: To detect the Enterococcus faecalis (E. faecalis) in post-treatment endodontic disease, and to analyze the relationship between the occurrence of E. faecalis and clinical symptom. METHODS: 108 teeth which need root canal retreatment were collected, and the clinical symptoms and physical signs were recorded. Bacterium samples from root canal were taken, and genome DNA from bacterial samples were extracted. The occurrence of E. faecalis by means of the polymerase chain reaction was investigated. RESULTS: The detection rate of E. faecalis in cases of root canal retreatment was 47.2%, while in cases with symptoms or signs, or cases with both symptoms and signs, the root canal E. faecalis detection rates were 52.6%, 57.9%, 62.5%. The detection rates of E. faecalis between cases with clinical symptom and without clinical symptom demonstrated statistical significance (P < 0.05). The detection rates between cases with both clinical symptom and manifestly aneretic root and cases without clinical symptom and manifestly aneretic root had statistical significance (P < 0.05). In the group of clinical symptom, the detection rate of E. faecalis in cases with biting pain was 66.7%, clearly higher than those without biting pain (P < 0.05). CONCLUSION: The occurrence of E. faecalis in cases of root canal retreatment correlates with clinical symptoms.

Preparation and metal-binding behaviour of chitosan functionalized by ester- and amino-terminated hyperbranched polyamidoamine polymers.

A series of insoluble chitosan (CTS) derivatives were prepared by grafting ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) into CTS using a divergent method by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups, and (2) amidation of the resulting esters with ethylenediamine (EDA). Their structures were characterized by infrared spectra (IR) and wide-angle X-ray diffraction (WAXD). The adsorption capabilities of the products for Au(3+), Pd(2+), Pt(4+), Ag(+), Cu(2+), Zn(2+), Hg(2+), Ni(2+), and Cd(2+) were studied. The results showed that the products exhibited better adsorption capabilities for Au(3+) and Hg(2+) than for other metal ions, and the adsorption capabilities of amino-terminated products were higher than those of ester-terminated ones. Also it was observed that a high percentage of grafting of PAMAM into CTS does not ensure a high adsorption capacity.

FeSO4 x 7H2O-catalyzed four-component synthesis of protected homoallylic amines.

An efficient catalytic four-component reaction of carbonyl compounds (or acetals/ketals), benzyl chloroformate (CbzCl), 1,1,1,3,3,3-hexamethyldisilazane (HMDS), and allyltrimethylsilane has been successfully developed to produce Cbz-protected homoallylic amines in the presence of 5 mol % of iron(II) sulfate heptahydrate (FeSO4 x 7H2O), an inexpensive and environmentally friendly catalyst, at room temperature.