Development of a Fatty Liver Model by Restricted Feeding of Lactating Sheep

Background:  As a frequent subclinical disease, fatty liver disease (FLD) is associated with a severe negative energy balance (NEB) during the early lactation period, and usually cause of economic loss to dairy farmers. Liver biopsy is the gold standard for the assessment of FLD. However, as an invasive procedure, liver biopsy has several limitations and such procedures are not readily available to dairy farmers. To further evaluate FLD in dairy cows, a FLD model of lactating sheep was developed by simulation of the state of negative energy balance (NEB).Materials, Methods & Results: Fourteen pregnancy thin-tail ewes were divided into control group (CG, n = 4), non-lamb restrained feeding group (NRG, n = 4) and single birth restrained feeding group (SRG, n = 6). After lambing, NRG and SRG ewe were received a feed restrained diet for 16 days. Liver biopsies and blood was collected on days 1, 4, 7, 10, 13, and 16, and biochemical parameters were analyzed. With restricted feeding and lactation administration, ewes in SRG showed increased liver fat concentrations (LFC) from days 4 post-administration and severe LFC was detected at day 13. Compared with CG, SRG sheep showed significant lower concentration of serum glucose (Glu) from days 7-13 and higher non-esterified fatty acid (NEFA) from days 4-16, β-hydroxybutyric acid (BHBA) from days 4-16, triglyceride from days 4-16, low-density lipoprotein cholesterol from days 4-16, lactate dehydrogenase (LDH) from days 13-16, aspartate aminotransferase (AST) at days 16. While, ewes in NRG showed normal LFC levels, and high concentration of serum Glu and insulin from days 4-16 were detected than CG and SRG ewes. With restricted feeding, ewes in NRG and SRG showed significant low level of revised quantitative insulin sensitivity check index from days 4-16 and high level of liver total cholesterol (TC) at day 16. Liver pathological characteristics showed LFC of NEB sheep was first detected around the liver portal area.Discussion: In this study, a model of FLD in lactating thin-tail sheep was developed by restricted feeding. Serum glucose concentrations were sharply decreased in SRG sheep，that was due to the large energy requirements for lactation and low energy provided by a restricted diet. While non-lactating NRG sheep demonstrated lower fat mobilization, which was considered to contribute to the high concentrations of serum glucose, as compared to SRG sheep. Meanwhile, in a state of NEB, oxaloacetic acid, which is generated by glycolysis and glycogenic amino acids, tends to be used for gluconeogenesis, that a generous amount of NEFA is incompletely oxidized to generate ketone body in SRG sheep, which is a major component of BHBA. Liver TC concentrations were significantly higher in NRG sheep than those in the SRG sheep, while liver triglyceride was significantly lower. The high level of liver TC in NRG sheep was considered to induce removal of triglyceride from the liver in the form of VLDL. Compared with CG sheep, although higher levels of liver TC were detected in SRG sheep on postpartum day 16, these levels were considered too low to induce significant depletion of triglycerides from the liver. In this study, the increase in serum AST and LDH was considered to cause by oxidative stress in mitochondria, and LDH concentrations was considered more sensitively than AST for LFC caused by NEB. Liver pathological characteristics showed that FLD caused by NEB had a major impact on reduced LFC, although no significant liver fibrosis was detected. While different from FLD caused by high-fat diet, TG was first accumulates around the hepatic lobules and LFC of NEB sheep was first detected around the liver portal area. It was considered that high concentrations of NEFA are prioritized for oxygenation in the liver portal area, which results in triglyceride accumulation

Co-existence of multiple distinct lineages in Vibrio parahaemolyticus serotype O4:K12

Vibrio parahaemolyticus is an important cause of foodborne gastroenteritis globally. Thermostable direct haemolysin (TDH) and the TDH-related haemolysin are the two key virulence factors in V. parahaemolyticus. Vibrio pathogenicity islands harbour the genes encoding these two haemolysins. The serotyping of V. parahaemolyticus is based on the combination of O and K antigens. Frequent recombination has been observed in V. parahaemolyticus , including in the genomic regions encoding the O and K antigens. V. parahaemolyticus serotype O4:K12 has caused gastroenteritis outbreaks in the USA and Spain. Recently, outbreaks caused by this serotype of V. parahaemolyticus have been reported in China. However, the relationships among this serotype of V. parahaemolyticus strains isolated in different regions have not been addressed. Here, we investigated the genome variation of the V. parahaemolyticus serotype O4:K12 using the whole-genome sequences of 29 isolates. We determined five distinct lineages in this strain collection. We observed frequent recombination among different lineages. In contrast, little recombination was observed within each individual lineage. We showed that the lineage of this serotype of V. parahaemolyticus isolated in America was different from those isolated in Asia and identified genes that exclusively existed in the strains isolated in America. Pan-genome analysis showed that strain-specific and cluster-specific genes were mostly located in the genomic islands. Pan-genome analysis also showed that the vast majority of the accessory genes in the O4:K12 serotype of V. parahaemolyticus were acquired from within the genus Vibrio . Hence, we have shown that multiple distinct lineages exist in V. parahaemolyticus serotype O4:K12 and have provided more evidence about the gene segregation found in V. parahaemolyticus isolated in different continents

Development of Kaptive databases for Vibrio parahaemolyticus O- and K-antigen genotyping.

Vibrio parahaemolyticus is an important food-borne human pathogen and presents immunogenic surface polysaccharides, which can be used to distinguish problematic and disease-causing lineages. V. parahaemolyticus is divided in 16 O-serotypes (O-antigen) and 71 K-serotypes (K-antigen). Agglutination tests are still the gold standard for serotyping, but many V. parahaemolyticus isolates are not typable by agglutination. An alternative for agglutination tests is genotyping using whole-genome sequencing data, by which K- and O- genotypes have been curated and identified previously for other clinically relevant organisms with the software tool Kaptive. In this study, V. parahaemolyticus isolates were serotyped and sequenced, and all known and several novel O- and K-loci were identified. We developed Kaptive databases for all O- and K-loci after manual curation of the loci. In our study, we could genotype the O- and K-loci of 98 and 93 % of the genomes, respectively, with a Kaptive confidence score higher than 'none'. The newly developed Kaptive databases with the identified V. parahaemolyticus O- and K-loci can be used to identify the O- and K-genotypes of V. parahaemolyticus isolates from genome sequences

An Iterative Calculation Method for Suspension Bridge’s Cable System Based on Exact Catenary Theory

In this paper, a flexible iterative method capable of considering the effects of slip between the main cable and saddles is presented for the analysis of the cable system in the suspension bridge. In the proposed procedure, nonlinear governing equations were first linearized based on the first-order Taylor expansion, then the tangent stiffness matrix was derived using appropriate numerical methods. Using the proposed flexible iterative procedure which is built upon the framework of Newton-Raphson method, the main cable’s unstrained length and equilibrium forces which satisfy the configuration and mechanical property under bridge’s completion state is obtained according to the main cable’s initial geometry parameters, saddles parameters and hangers arrangement. Based on form-finding analysis, the method is also proposed to calculate the main cable’s internal forces and displacements during the erection of stiffening girder; the reliability and efficiency of the method is demonstrated by two typical numerical examples. Furthermore, the proposed method is used as a pro-processing tool in the finite element analyses of a cable structure. Finally, a numerical example (Yingwuzhou Yangtze River Bridge) is reported to illustrate the advantages of the proposed method, including the accurate predictions of the main cable’s unstrained length and the excursion of the saddles, which is crucial for choosing appropriate saddles parameters

Enhanced particle swarm optimization for size and shape optimization of truss structures

10.1080/0305215X.2016.1273912Engineering Optimization49111939-195

Isolation and drug resistance of 2 stains of Yersinia from food

Objective Identification and drug resistance of two stains of Yersinia aleksiciae (Ya) isolated from different foods were studied, which provided technical reserves for the isolation of the new Yersinia spp. Methods A total of 300 food samples were collected from August 2018 to March 2019, including pork, beef and chicken. Separation culture, biochemical identification, drug resistance test, and whole genome sequencing analysis were performed on the isolated suspected Ya. Results The positive rate of Ya in food samples was 0.7% (2/300). In biochemical identification, Ya was distinguished from Yersinia enterocolitica (Ye) by lysine decarboxylase test, and Ya was positive for lysine decarboxylase while Ye was negative. Ya didn’t exhibit natural resistance to ampicillin, cephalosporin I, ticarcillin and other drugs similar to Ye, and the drug resistance was different between the two strains. 16S rRNA, gyrB, rpoD genes were compared by whole genome sequencing to confirm that the two isolates were Ya. Conclusion The two strains of Ya were isolated and found in China for the first time. There was also no report on the isolation of these strains from food. The method provided in this study could be used for the isolation and identification of new Yersinia spp

Erythromycin resistance of clinical Campylobacter jejuni and Campylobacter coli in Shanghai, China

Campylobacter species are zoonotic pathogens, as well as the prevalent cause of foodborne bacterial gastroenteritis. The spread of antimicrobial-resistant strains poses a serious threat to global public health and attracts attention worldwide, but information about clinical Campylobacter is relatively limited compared to isolates from food and animals. The current study illustrated the prevalence and antimicrobial resistance profiles of Campylobacter jejuni and Campylobacter coli isolates collected from a consecutive surveillance program between 2012 and 2019 in Shanghai, China, using antimicrobial susceptibility testing and whole-genome sequencing. Among the 891 Campylobacter strains (761 C. jejuni and 130 C. coli) isolates collected, high portions above 90% of resistance to ciprofloxacin, nalidixic acid, and tetracycline were observed for both C. jejuni and C. coli. The most common MDR profiles represented by C. jejuni and C. coli were combination of ciprofloxacin, tetracycline, florfenicol and nalidixic acid (5.39%), and azithromycin, ciprofloxacin, erythromycin, gentamicin, tetracycline, clindamycin, nalidixic acid (28.46%), respectively. The erythromycin resistance of C. coli (59.23%) is higher than C. jejuni (2.50%). A total of 76 erythromycin resistant isolates (16 C. jejuni and 60 C. coli) were sequenced using Illumina platform for determining the genotypes, antimicrobial resistance patterns and phylogeny analysis. Multilocus sequence typing (MLST) analysis showed a high genetic diversity with 47 sequence types (STs), including 4 novel alleles and 12 new STs. The most abundant clonal complexes (CCs) were CC-403 (31.25%) and CC-828 (88.33%) for C. jejuni and C. coli, respectively. Among the 76 erythromycin-resistant isolates, mutation A2075G in 23S rRNA and erm(B) gene were detected in 53.95 and 39.47%, respectively. The erm(B) gene was identified exclusively in 30 C. coli isolates. All these erm(B) positive isolates were multi-drug resistant. Furthermore, comparison of the erm(B)-carrying isolates of multiple sources worldwide demonstrated the possibility of zoonotic transmission of erm(B) in Campylobacter. These findings highlight the importance of continuous surveillance of erythromycin resistance dissemination in Campylobacter which may compromise the effectiveness of antimicrobial therapy

Transplantation of active nucleus pulposus cells with a keep-charging hydrogel microsphere system to rescue intervertebral disc degeneration

Abstract Background Cell transplantation has been demonstrated as a promising approach in tissue regeneration. However, the reactive oxygen species (ROS) accumulation and inflammation condition establish a harsh microenvironment in degenerated tissue, which makes the transplanted cells difficult to survive. Methods In this study, we constructed a keep-charging hydrogel microsphere system to enable cells actively proliferate and function in the degenerated intervertebral disc. Specifically, we combined Mg2+ to histidine-functionalized hyaluronic acid (HA-His-Mg2+) through coordination reaction, which was further intercrossed with GelMA to construct a double-network hydrogel microsphere (GelMA/HA-His-Mg2+, GHHM) with microfluidic methods. In vitro, the GHHM loaded with nucleus pulposus cells (GHHM@NPCs) was further tested for its ability to promote NPCs proliferation and anti-inflammatory properties. In vivo, the ability of GHHM@NPCs to promote regeneration of NP tissue and rescue intervertebral disc degeneration (IVDD) was evaluated by the rat intervertebral disc acupuncture model. Results The GHHM significantly enhanced NPCs adhesion and proliferation, providing an ideal platform for the NPCs to grow on. The loaded NPCs were kept active in the degenerative intervertebral disc microenvironment as charged by the Mg2+ in GHHM microspheres to effectively support the loaded NPCs to reply against the ROS-induced inflammation and senescence. Moreover, we observed that GHHM@NPCs effectively alleviated nucleus pulposus degeneration and promoted its regeneration in the rat IVDD model. Conclusion In conclusion, we constructed a keep charging system with a double-network hydrogel microsphere as a framework and Mg2+ as a cell activity enhancer, which effectively maintains NPCs active to fight against the harsh microenvironment in the degenerative intervertebral disc. The GHHM@NPCs system provides a promising approach for IVDD management. Graphical Abstrac

Decreased frequency of peripheral blood CD8+CD25+FoxP3+regulatory T cells correlates with IL-33 levels in pre-eclampsia

Objective: We aimed to investigate the role of CD8+CD25+Foxp3+regulatory T (Treg) cells in pre-eclampsia (PE). Methods: This was a cross-sectional study of 46 patients with PE and 24 normotensive women within the third trimester of gestation. We analyzed the percentages of CD8+CD25+Foxp3+Treg cells in peripheral blood using flow cytometry and the serum levels of interleukin (IL)-6, IL-17A, IL-10, TGF-β1, IL-1β, and IL-33 by Luminex 200. Results: We found that patients with PE had lower percentages of CD8+CD25+Foxp3+Treg cells than normotensive pregnant women. In addition, the percentage of CD8+CD25+Foxp3+Treg cells was positively correlated with IL-33 concentration and negatively correlated with IL-17A concentration in patients with PE. We also found that IL-33 treatment can induce proliferation of CD8+CD25+Foxp3+Treg cells in vitro. Conclusions: These findings suggest that the reduced CD8+CD25+Foxp3+Treg cells may play a role in the pathogenesis of PE. Abbreviations PE: pre-eclampsia; PBMCs: peripheral blood mononuclear cells; CTLA-4: cytotoxic T-lymphocyteantigen-4; APCs: antigen presenting cells; TGF-β: transforming growth factor-β; IL: interleukin; Treg: cells regulatory T cells; PBS: phosphate-buffered saline; Foxp3: forkhead Box protein 3; HELLPs: hemolysis, elevated liver enzyme and low platelet syndrom