Xiang Chen

Emory University | EU · History and Social Sciences Division

Background Control of Tuberculosis (TB) infection is mainly the result of productive teamwork between T-cell populations and antigen presenting cells (APCs). However, APCs activation at the site of initiating cellular immune response during BCG early infection is not completely understood. Methods In this study, we injected C57BL/6 mice in intrave...

hHR23a (human homolog of Rad23 a) functions in nucleotide excision repair and proteasome-mediated protein degradation. It contains an N-terminal ubiquitin-like (UBL) domain, an xeroderma pigmentosum C (XPC)-binding domain, and a ubiquitin-associated (UBA) domain preceding and following the XPC-binding domain. Each of the four structural domains are...

The adsorption process is the first step in the lifecycle of phages and plays a decisive role in the entire infection process. Identifying the adsorption mechanism of phages not only makes phage therapy more precise and efficient but also enables the exploration of other potential applications and modifications of phages. Phage LP31 can lyse multip...

Nearly a quarter of the world's population is infected with Mycobacterium tuberculosis and remains long-term asymptomatic infection. Rv2626c is a latent infection-related protein regulated by DosR of M. tuberculosis. In this study, the Rv2626c protein was prokaryotically expressed and purified, and its immunobiological characteristics were analyzed...

Listeria monocytogenes (Lm) is a deadly foodborne pathogen that comprises 14 serotypes, among which, serotype 4b Lm is the primary cause of listeriosis outbreaks in humans and animals. Here, we evaluated the safety, immunogenicity, and protective efficacy of a serotype 4b vaccine candidate Lm NTSNΔactA/plcB/orfX in sheep. The infection dynamics, cl...

Carbapenem-resistant Enterobacteriaceae infections are among the most serious threats to human and animal health worldwide. Of the 1013 strains of Escherichia coli isolated and identified in 14 regions of China from 2007 to 2018, seven strains were resistant to meropenem and all were positive for blaNDM. The seven New Delhi metallo-β-lactamase (NDM...

UBQLN1 functions in autophagy and proteasome-mediated protein degradation. It contains an N-terminal ubiquitin-like domain (UBL), a C-terminal ubiquitin-associated domain (UBA), and a flexible central region which functions as a chaperone to prevent protein aggregation. Here, we report the ¹H, ¹⁵N, and ¹³C resonance assignments for the backbone (NH...

Background: Hyperlipidemia is a major risk factor for many diseases. Previous studies have shown that diet is closely associated with hyperlipidemia. However, the relationship between cooking methods and hyperlipidemia remains unclear. The objective of this study was to identify the major cooking patterns existing in the Eastern Chinese population...

The E3 ligase E6AP/UBE3A has a dedicated binding site in the 26S proteasome provided by the RAZUL domain of substrate receptor hRpn10/S5a/PSMD4. Guided by RAZUL sequence similarity, we test and demonstrate here that the E6AP AZUL binds transiently to the UBA of proteasomal shuttle factor UBQLN1/2. Despite a weak binding affinity, E6AP AZUL is recru...

This study aims to develop a method to detect bovine multi-cytokines based on flow cytometry. Previously we have prepared and screened monoclonal antibodies against bovine cytokines IFN-γ, IL-2, TNF-α, IP-10 and MCP-1. These bovine cytokine monoclonal antibodies were fluorescently labeled, and the combination of antibody and cell surface molecules...

Salmonella enterica serovar Dublin ( S . Dublin) is an important zoonotic pathogen with high invasiveness. In the prevention and control of the Salmonella epidemic, the live attenuated vaccine plays a very important role. To prevent and control the epidemic of S . Dublin in cattle farms, the development of more effective vaccines is necessary. In t...

In recent years, foodborne diseases caused by pathogens have been increasing. Therefore, it is essential to control the growth and transmission of pathogens. Bacteriophages (phages) have the potential to play an important role in the biological prevention, control, and treatment of these foodborne diseases due to their favorable advantages. Phages...

As a natural alternative to traditional antimicrobials, phages are being recognised as highly effective control agents for Salmonella and other foodborne bacteria. Due to the high diversity of Salmonella serotypes and the emergence of phage-resistant strains, attempting to isolate more widespread, strictly lytic Salmonella phages is highly warrante...

Salmonella enteritidis is a major causative agent of foodborne illnesses worldwide. As the traditional serotyping and quantification methods are labor-intensive, time-consuming, and expensive, faster and more convenient molecular diagnostic methods are needed. In this study, we developed and validated a rapid duplex TaqMan real-time polymerase chai...

The internalin family proteins, which carry the leucine repeat region structural motif, play diverse roles in Listeria monocytogenes (Lm) infection and pathogenesis. Although Internalin F, encoded by inlF , was identified more than 20 years ago, its role in the Lm anti-inflammatory response remains unknown. Lm serotype 4b isolates are associated wi...

de Almeida et al. (2021) developed a temporally controlled CRISPR-Cas9 screen to identify mechanisms controlling MYC levels and discovered that intact proteasomes are imported into the nucleus by AKIRIN2 binding to proteasomes at one end and a nuclear import receptor at the other.

Proteasome substrate receptor hRpn13 is a promising anti-cancer target. By integrated in silico and biophysical screening, we identified a chemical scaffold that binds hRpn13 with non-covalent interactions that mimic the proteasome and a weak electrophile for Michael addition. hRpn13 Pru domain binds proteasomes and ubiquitin whereas its DEUBAD dom...

To disclose the antimicrobial susceptibility and wide adaptability of commonly occurring genotypes of Salmonella enterica serovar Typhimurium, the antimicrobial resistance and multilocus sequence typing (MLST) profiles of 196 Salmonella Typhimurium isolates (136 from food-producing animals, 19 from environments, 15 from markets, and 26 from humans)...

Through long-term coevolution with its host, Mycobacterium tuberculosis ( M. tuberculosis ) uses multiple strategies to escape host defenses. The M. tuberculosis Rv0927c protein is predicted to be a short-chain dehydrogenase/reductase related to bacterial metabolism. However, the role of Rv0927c during M. tuberculosis infection remains unclear. Her...

Proteasome substrate receptor hRpn13 is a promising anti-cancer target. By integrated in silico and biophysical screening, we identified a chemical scaffold that binds hRpn13 with non-covalent interactions that mimic the proteasome and a weak electrophile for Michael addition. hRpn13 Pru domain binds proteasomes and ubiquitin whereas its DEUBAD dom...

The study of the interaction mechanism between bacteriophage and host is helpful in promoting development of bacteriophage applications. The mechanism of the interaction with the phage was studied by constructing the rfbN gene deletion and complemented with strains of Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimuri...

Salmonellosis occurs frequently worldwide, causing serious threats to public health. The abuse of antibiotics is increasing antibiotic resistance in bacteria, thereby making the prevention and control of Salmonella more difficult. A phage can help control the spread of bacteria. In this study, the lytic phage S55, whose host bacterium is Salmonella...

The 26S proteasome is specialized for regulated protein degradation. It is formed by a regulatory particle (RP) that recognizes ubiquitinated substrates and caps a hollow cylindrical core particle (CP) where substrates are proteolyzed. Structural heterogeneity caused by dynamics makes it challenging to observe ubiquitin chains at the RP by cryogeni...

Purpose To determine factors associated with non-adherence to contact lens wear schedule involving single vision and myopia control contact lenses in children. Methods Data from 379 children enrolled in a prospective, double masked, randomized clinical trial, aged 8–13 years, cycloplegic spherical equivalent of -0.75 to -3.50D and wearing either:...

The 26S proteasome is responsible for regulated proteolysis in eukaryotic cells. Its substrates are diverse in structure, function, sequence length, and amino acid composition, and are targeted to the proteasome by post-translational modification with ubiquitin. Ubiquitination occurs through a complex enzymatic cascade and can also signal for other...

Pullorum is a chicken–specific systemic disease caused by Salmonella enterica serovar Gallinarum biovar Pullorum (S. Pullorum). This study was carried out to provide basic data for understanding the trends of S. Pullorum. A total of 652 S. Pullorum isolates collected in China during 1962–2019 were examined. Overall, 525 (80.5%) isolates were resist...

Background Targeting glutamine metabolism in cancer has become an increasingly vibrant area of research. Mutant IDH1 (IDH1 mut ) gliomas are considered good candidates for targeting this pathway because of the contribution of glutamine to their newly acquired function: synthesis of 2-hydroxyglutarate (2HG). Methods We have employed a combination o...

The 26S proteasome is specialized for regulated protein degradation and formed by a dynamic regulatory particle (RP) that caps a hollow cylindrical core particle (CP) where substrates are proteolyzed. Its diverse substrates unify as proteasome targets by ubiquitination. We used cryogenic electron microscopy (cryo-EM) to study how human 26S proteaso...

Mycobacterium bovis, the causative agent of bovine tuberculosis (bTB), poses a risk of infection for livestock, humans, and wildlife. An interferon (IFN)-γ release assay has been used with tuberculin skin tests to detect bTB; however, infected animals may still be missed. Previous studies have suggested that bovine interleukin-2 (BoIL-2) may act as...

Visual coverage is an important task for environment perception. In this paper, the coverage of a large-scale three-dimensional (3-D) scene represented by a polygon mesh model is considered, and a visual sensor network deployment algorithm is proposed through the combination of space partition, greedy and local search procedures. Comparing with exi...

A novel real-time time-optimal trajectory planning (TOTP) approach is proposed for rotorcrafts under velocity constraints and complex non-convex thrust, attitude input constraints. Different from existing works, the proposed method is the first real-time TOTP solution for rotorcrafts subject to velocity constraints and these non-convex input constr...

Salmonella 4,[5],12:i:- is a monophasic variant of Salmonella Typhimurium, which is responsible for global foodborne disease outbreaks. Here, 255 S. 4,[5],12:i:- strains isolated from humans (11.0%) or food-borne animals (89.0%) between 2010 and 2018 were examined. Tests of susceptibility to 19 antimicrobial agents using the broth micro dilution me...

Regulated proteolysis by proteasomes involves ~800 enzymes for substrate modification with ubiquitin, including ~600 E3 ligases. We report here that E6AP/UBE3A is distinguished from other E3 ligases by having a 12 nM binding site at the proteasome contributed by substrate receptor hRpn10/PSMD4/S5a. Intrinsically disordered by itself, and previously...

Salmonella has been known as the most important foodborne pathogen, which can infect humans via consuming contaminated food. Chicken meat has been known as an important vehicle to transmit Salmonella by the food supply chain. This study determined the prevalence, antimicrobial resistance, and genetic characteristics of Salmonella at different chick...

An Escherichia coli strain isolated from the feces of swine at a pork slaughterhouse in Henan province China was found to possess two colistin-resistance genes, mcr-1 and mcr-3, plus 16 additional resistance genes. Genes mcr-1.1 and mcr-3.1 were identified on IncHI2 and IncX1 type plasmids, respectively. Transconjugants (containing mcr-3, mcr-1&mcr...

This paper proposes a novel adaptive image-based output feedback visual servoing approach to control a multirotor to the desired pose by using a minimum onboard sensor suite which consists of an inertial measurement unit and a monocular camera. Different from ‘perspective moment’ (PM), a new type of image feature is designed as ‘rotated perspective...

CRISPR-based typing was performed to subtype isolates of S. Typhimurium and its monophasic variant Salmonella 4,[5],12:i:- from humans and animals between 2009 and 2017 in China. CRISPR typing classified all isolates into two lineages and four sub-lineages. All isolates from Lineage II and Lineage IB-1 were Salmonella Typhimurium. All of Salmonella...

Coverage is a basic and critical issue for design and deployment of visual sensor networks, however, the optimization problem is very challenging especially when considering coverage of three-dimensional (3-D) scenarios. This paper provides a brief survey of mainstream coverage optimization methods for visual sensor networks, including the greedy a...

In this study, a carbapenem-resistant Salmonella enterica serovar Typhimurium strain W131 (sequence type 34) was isolated from retail pork in Jiangsu province, China. An IncX3 plasmid carrying blaNDM-5 element was identified in this strain by whole-genome sequencing analysis. The conjugation experiment demonstrated that the plasmid can be transferr...

Nanomaterials of Al2O3 and TiO2 have been proved to promote the spread of antibiotic resistance genes (ARGs) by horizontal gene transfer. In this work, we found that Fe2O3@MoS2 nanocomposite inhibited the horizontal gene transfer (HGT) by inhibiting the conjugative transfer mediated by RP4-7 plasmid. To discover the mechanism of Fe2O3@MoS2 inhibiti...

Regulated proteolysis by the proteasome involves ~800 enzymes for substrate modification with ubiquitin, of which ~600 are E3 ligases. We report here that E6AP/UBE3A is distinguished from other ubiquitin E3 ligases by having a 12 nM binding site at the proteasome contributed by substrate receptor hRpn10/PSMD4/S5a. Intrinsically disordered by itself...

In this study, we found that Fe3O4 promoted horizontal gene transfer (HGT), but when Fe3O4 was composited with MoS2, the Fe3O4@MoS2 nanocomposite interacting with bacteria significantly blocked the HGT in the conjugation system. qPCR was used to analyze the expression of genes belonging to the chromosome and plasmid in the conjugation system. Resul...

The foodborne pathogen Listeria monocytogenes (Lm) is a highly heterogeneous species and currently comprises of 4 evolutionarily distinct lineages. Here, we characterize isolates from severe ovine listeriosis outbreaks that represent a hybrid sub-lineage of the major lineage II (HSL-II) and serotype 4h. HSL-II isolates are highly virulent and exhib...

In the process of bacteriophage and bacteria struggle, adsorption is the key factor to determine who is the winner. In this paper, the molecular mechanism of tailed bacteriophage recognition and adsorption to host and the strategy of "fighting wisdom and courage" between them are reviewed.

Purpose We aimed to determine myopia control efficacy with novel contact lenses (CL) that (1) reduced both central and peripheral defocus, and (2) provided extended depth of focus with better global retinal image quality for points on, and anterior to, the retina and degraded for points posterior to the retina. Methods Children (n = 508, 8–13 year...

Aim: To determine if the treatment effect of myopia control contact lenses (MCCL) is dependent on age, refractive error, gender and/or parental myopia in Chinese children aged 8 to 13 years. Methods: Two year progression of 508 Chinese children, 8 to 13 years with baseline refractive error ranging from -0.75 to -3.50D, cylinder≤ -0.75D , was estima...

Pullorum disease, an acute poultry septicemia caused by Salmonella Gallinarum biovar Pullorum, is fatal for young chickens and is a heavy burden on poultry industry. The pathogen is rare in most developed countries but still extremely difficult to eliminate in China. Efficient epidemiological surveillance necessitates clarifying the origin of the i...

Salmonella is a worldwide foodborne pathogen causing human disease. Food handlers, who are potential carriers of Salmonella, may transmit the pathogen to consumers through food. To determine the prevalence of Salmonella enterica serovars among food handlers working in the catering industry in Nantong, China, a total of 214,542 food handlers' fecal...

Salmonella enterica subsp. enterica serovar Gallinarum biovar Pullorum (Salmonella Pullorum) is a host-specific serovar causing systemic infection with high mortality in young chicks. Pullorum disease is characterized by white diarrhea. However, arthritis has become increasingly frequent recently, particularly in southern China. The aim of the pres...

Substitution of the m,p-chloro groups of bis-benzylidinepiperidone RA190 for p-nitro, generating RA183, enhanced covalent drug binding to Cys88 of RPN13. Treatment of cancer cell lines with RA183 inhibited ubiquitin-mediated protein degradation, resulting in rapid accumulation of high-molecular-weight polyubiquitinated proteins, blockade of NFκB si...

In this study, Salmonella prevalence and antimicrobial resistance were evaluated at various production stages in 2 geographically separated breeder farms (referred to as G and F). Day-old chicks for the breeder flock at farm F were purchased from farm G. A total of 219 Salmonella isolates, all identified as Salmonella enterica subsp. enterica serov...

Background: Control of Mycobacterium tuberculosis (Mtb) infection requires CD4+ T-cell responses and major histocompatibility complex class II (MHC II) presentation of Mtb antigens (Ags). Dendritic cells (DCs) are the most potent of the Ag-presenting cells and are central to the initiation of T-cell immune responses. Much research has indicated th...

This paper proposes a visual distance approach for multi-camera deployment through parallel coverage optimization over three-dimensional (3-D) space to inspect 3-D objects. The key idea is the proposal of a new "visual distance" between a single camera and a scene point, which takes into account multiple coverage criteria. Specifically, the effecti...

Purpose: To evaluate the relation between subjective responses to contact lenses (CL) wear and compliance in children when they were assigned wearing either single vision (SVCL) or novel CL designed to control progression of myopia. Methods: A retrospective, case control analysis of a clinical trial conducted in Guangzhou, China where children (n=...

Compared with the size of a calibration board, the inspected area within the camera field of view is much bigger in many applications such as visual surveillance systems. In this paper, we present a global image-to-ground homography calibration method to obtain the mapping between the image and the planar scene lying in the whole camera field of vi...

Salmonella enterica serovar Enteritidis (S. Enteritidis) is one of the most prevalent serotypes in Salmonella isolated from poultry and the most commonly reported cause of human salmonellosis. In this study, we aimed to assess the genetic diversity of 329 S. Enteritidis strains isolated from different sources from 2009 to 2016 in China. Clustered r...

Deaths associated with tuberculosis (TB) is rising and accounted for 1.4 million deaths in 2015 many of which were due to drug-resistant bacteria. Vaccines represent an important medical intervention, but the current Bacilli Calmette-Guerin (BCG) vaccine is not ideal for the protection of teenagers and adults. Therefore, a safe and effective vaccin...

This study was undertaken to acquire data on Salmonella contamination of whole raw chickens, eggs, and vegetables available to consumers in Yangzhou city, China, between April 2011 and March 2012. In total, 240 chicken carcasses were tested, and the overall contamination rate for Salmonella was 33.8%. While the prevalence of Salmonella in 100 eggs...

The pathogen Salmonella Pullorum is the causative agent of persistent systemic infection of poultry, leading to economic losses in developing countries due to morbidity, mortality and reduction in egg production. These infections may result in vertical transmission to eggs or progeny. Limited information is available regarding the mechanisms involv...

Salmonella enterica subsp. enterica serovar Gallinarum biovar Pullorum (Salmonella Pullorum) is highly adapted to chickens causing an acute systemic disease that results in high mortality. Vaccination represents one approach for promoting animal health, food safety and reducing environmental persistence in Salmonella control. An important considera...

Rad23 functions in nucleotide excision repair and proteasome-mediated protein degradation. It has four distinct structural domains that are connected by flexible linker regions, including an N-terminal ubiquitin-like (UBL) domain that binds proteasomes. We report in this NMR study the 1H, 15N and 13C resonance assignments for the backbone and side...