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

Plasmonic hot electrons for sensing, photodetection, and solar energy applications: A perspective

In plasmonic metals, surface plasmon resonance decays and generates hot electrons and hot holes through non-radiative Landau damping. These hot carriers are highly energetic, which can be modulated by the plasmonic material, size, shape, and surrounding dielectric medium. A plasmonic metal nanostructure, which can absorb incident light in an extended spectral range and transfer the absorbed light energy to adjacent molecules or semiconductors, functions as a “plasmonic photosensitizer.” This article deals with the generation, emission, transfer, and energetics of plasmonic hot carriers. It also describes the mechanisms of hot electron transfer from the plasmonic metal to the surface adsorbates or to the adjacent semiconductors. In addition, this article highlights the applications of plasmonic hot electrons in photodetectors, photocatalysts, photoelectrochemical cells, photovoltaics, biosensors, and chemical sensors. It discusses the applications and the design principles of plasmonic materials and devices

Preliminary Trial to Establish Artificial Grassland in Tibet, China

Tibet Autonomous Region with an average altitude of more than 4,000 m above sea level, altogether cover an area of 1.22 million km2, equivalent to one-eight of the total area of China. High mountains along with forests and rivers in Tibet consist of an important ecological barrier for protecting parts of inland ecosystems. Tibet is also one of the five major pastoral areas in China. The grassland in Tibet covers 0.83 million km2, but the grass is sparse and low, and with low yield in this area. There are nearly 2.8 million people in this region, while the area of arable land is less than 2.533 thousand km2. Nearly 40.5 million tons of hay are needed for about 45 million sheep units in Tibet (Yu et al., 2010), while the actual amount is less than 20 million tons (including 15 million tons per year from natural grassland, and 2～3 million tons per year from the straw of naked barley). It exacerbating the degradation of natural grassland for the contradiction between livestock and grass. Research shows that the most effective measure to maintain local economic growth, coordinated development of ecological security and curb the further degradation of the grassland in Tibet is by planting high yielding and high quality forage crops, changing the traditional way of free grazing and implementing captive feeding gradually

Application of Improved Jellyfish Search algorithm in Rotate Vector reducer fault diagnosis

In order to overcome the low accuracy of traditional Extreme Learning Machine (ELM) network in the performance evaluation of Rotate Vector (RV) reducer, a pattern recognition model of ELM based on Ensemble Empirical Mode Decomposition (EEMD) fusion and Improved artificial Jellyfish Search (IJS) algorithm was proposed for RV reducer fault diagnosis. Firstly, it is theoretically proved that the torque transmission of RV reducer has periodicity during normal operation. The characteristics of data periodicity can be effectively reflected by using the test signal periodicity characteristics of rotating machinery and EEMD. Secondly, the Logistic chaotic mapping of population initialization in JS algorithm is replaced by tent mapping. At the same time, the competition mechanism is introduced to form a new IJS. The simulation results of standard test function show that the new algorithm has the characteristics of faster convergence and higher accuracy. The new algorithm was used to optimize the input layer weight of the ELM, and the pattern recognition model of IJS-ELM was established. The model performance was tested by XJTU-SY bearing experimental data set of Xi'an Jiaotong University. The results show that the new model is superior to JS-ELM and ELM in multi-classification performance. Finally, the new model is applied to the fault diagnosis of RV reducer. The results show that the proposed EEMD-IJS-ELM fault diagnosis model has higher accuracy and stability than other models

Genome-Wide Transcriptional Profiling of the Response of Staphylococcus aureus to Cryptotanshinone

Staphylococcus aureus (S. aureus) strains with multiple antibiotic resistances are increasingly widespread, and new agents are required for the treatment of S. aureus. Cryptotanshinone (CT), a major tanshinone of medicinal plant Salvia miltiorrhiza Bunge, demonstrated effective in vitro antibacterial activity against all 21 S. aureus strains tested in this experiment. Affymetrix GeneChips were utilized to determine the global transcriptional response of S. aureus ATCC 25923 to treatment with subinhibitory concentrations of CT. Transcriptome profiling indicated that the antibacterial action of CT may be associated with its action as active oxygen radical generator; S. aureus undergoes an oxygen-limiting state upon exposure to CT