Microbial Diversity and Community Structure of Chinese Fresh Beef during Cold Storage and Their Correlations with Off-Flavors.

To investigate the diversity and dynamics of microorganisms in Chinese fresh beef (CFB) without acid discharge treatment during cold storage, high-throughput sequencing was employed to analyze the CFB refrigerated for 0, 3, 7, and 10 days. The results showed that the community richness of the fungi and bacteria decreased significantly. However, the diversity decreased in the early stage and increased in the later stage. At the phylum level, Ascomycota (74.1-94.1%) and Firmicutes (77.3-96.8%) were the absolutely dominant fungal and bacterial phyla. The relative abundance of both fungal and bacterial phyla displayed a trend of increasing and then decreasing. At the genus level, Candida (29.3-52.5%) and Lactococcus (19.8-59.3%) were, respectively, the dominant fungal and bacterial genera. The relative abundance of Candida showed a trend of increasing and then decreasing, while Lactococcus possessed the opposite trend. KEGG metabolic pathways analysis suggested that carbohydrate metabolism, membrane transport, and amino acid metabolism were the major metabolic pathways of bacteria. Bugbase prediction indicated the major microbial phenotype of bacteria in CFB during cold storage was Gram-positive (17.2-31.6%). Correlation analysis suggested that Lactococcus, Citrobacter, Proteus, and Rhodotorula might be the main microorganisms promoting the production of off-flavor substances in CFB. This study provides a theoretical basis for the preservation of Chinese fresh beef.

The Contribution of Microorganisms to the Quality and Flavor Formation of Chinese Traditional Fermented Meat and Fish Products.

Guizhou sour meat and sour fish, Chaoshan fish sauce, Sichuan sausage and bacon, Cantonese sausage, Jinhua ham, and Xinjiang air-dried beef are eight representatives of Chinese traditional fermented meat and fish products (FMFPs), which are favored by Chinese consumers due to their high nutritional value and quality. The quality of the spontaneously fermented Chinese traditional FMFP is closely correlated with microorganisms. Moreover, the dominant microorganisms are significantly different due to regional differences. The effects of microorganisms on the texture, color, flavor, nutrition, functional properties, and safety of Chinese traditional FMFPs have not been not fully described. Additionally, metabolic pathways for flavor formation of Chinese traditional FMFPs have not well been summarized. This article describes the seven characteristic Chinese traditional FMFPs and correlated dominant microorganisms in different regions of China. The effects of microorganisms on the texture, color, and flavor of Chinese traditional FMFPs are discussed. Furthermore, the metabolic pathways of microbial regulation of flavor formation in Chinese traditional FMFPs are proposed. This work provides a theoretical basis for improvement of Chinese traditional FMFPs by inoculating functional microorganisms isolated from Chinese traditional fermented foods.

[Design and validation of a novel knee biomechanical test method].

A novel structural dynamics test method and device were designed to test the biomechanical effects of dynamic axial loading on knee cartilage and meniscus. Firstly, the maximum acceleration signal-to-noise ratio of the experimental device was calculated by applying axial dynamic load to the experimental device under unloaded condition with different force hammers. Then the experimental samples were divided into non-specimen group (no specimen loaded), sham specimen group (loaded with polypropylene samples) and bovine knee joint specimen group (loaded with bovine knee joint samples) for testing. The test results show that the experimental device and method can provide stable axial dynamic load, and the experimental results have good repeatability. The final results confirm that the dynamic characteristics of experimental samples can be distinguished effectively by this device. The experimental method proposed in this study provides a new way to further study the biomechanical mechanism of knee joint structural response under axial dynamic load.

The Volatile Flavor Substances, Microbial Diversity, and Their Potential Correlations of Inner and Surface Areas within Chinese Qingcheng Mountain Traditional Bacon.

The objective of this study was to explore the microbial diversity, volatile flavor substances, and their potential correlations in inner and surface Chinese Qingcheng Mountain traditional bacon (CQTB). The results showed that there were 39 volatile flavor substances in inner and surface CQTB detected by headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS). Moreover, significant differences in volatile flavor substances between the inner and surface CQTB were observed. Sixteen key volatile flavor substances were screened (OAV > 1), including guaiacol, nonanal, ethyl isovalerate, and others. High-throughput sequencing (HTS) result indicated that Firmicutes, Proteobacteria, and Actinobacteria were the predominant bacterial phyla, and Ascomycota and Mucoromycota were the predominant fungal phyla. Staphylococcus, Psychrobacter, and Brochothrix were the predominant bacteria, and Debaryomyces, Penicillium, and Mucor were the predominant fungal genera. Spearman correlation coefficient analysis suggested that Apiotrichum and Lactobacillus were closely and positively correlated with the formation of key phenol compounds. The present work demonstrates the microbial diversity and related volatile flavor substances and their potential correlations in CQTB and provides a theoretical basis for the development of microbial starter culture and green processing of CQTB.

Potential Correlation between Microbial Diversity and Volatile Flavor Substances in a Novel Chinese-Style Sausage during Storage.

A novel Chinese-style sausage with Chinese traditional fermented condiments used as additional ingredients is produced in this study. The aim of this study was to investigate the microbial community's structure, the volatile flavor substances and their potential correlation in the novel Chinese sausage. High-throughput sequencing (HTS) and solid-phase microextraction-gas chromatography-mass spectrometry (GC-MS) were, respectively, used to analyze the microbial diversity and volatile flavor substances of the novel Chinese-style sausage during storage. The results showed that Firmicutes, Proteobacteria and Actinobacteria were the predominant bacterial genera, and Hyphopichia and Candida were the predominant fungal genera. A total of 88 volatile flavor substances were identified through GC-MS, among which 18 differential flavor compounds were screened (VIP > 1), which could be used as potential biomarkers to distinguish the novel sausages stored for different periods. Lactobacillus exhibited a significant negative correlation with 2,3-epoxy-4,4-dimethylpentane and acetoin and a significant positive correlation with 2-phenyl-2-butenal. Hyphopichia significantly positively correlated with ester. Leuconostoc significantly positively correlated with ethyl caprate, ethyl palmate, ethyl tetradecanoate and ethyl oleate while it negatively correlated with hexanal. This study provides a theoretical basis for revealing the flavor formation mechanisms and the screening of functional strains for improving the flavor quality of the novel Chinese-style sausage.

Low-Dose Ketamine-Induced Deficits in Arbitrary Visuomotor Mapping in Monkeys.

Ketamine, an NMDA antagonist, is widely used in clinical settings. Recently, low-dose ketamine has gained attention because of its promising role as a rapid antidepressant. However, the effects of low-dose ketamine on brain function, particularly higher cognitive functions of primate brains, are not fully understood. In this study, we used two macaques as subjects and found that acute low-dose ketamine administration significantly impaired the ability for arbitrary visuomotor mapping (AVM), a form of associative learning (AL) essential for flexible behaviors, including executions of learned stimuli-response contingency or learning of new contingencies. We conducted in-depth analyses and identified intrinsic characteristics of these ketamine-induced functional deficits, including lowered accuracy, prolonged time for planning and movement execution, increased tendency to make errors when visual cues are changed from trial to trial, and stronger impact on combining associative learning and another key higher cognitive function, working memory (WM). Our results shed new light on how associative learning relies on the NMDA-mediated synaptic transmission of the brain and contribute to a better understanding of the potential acute side effects of low-dose ketamine on cognition, which can help facilitate its safe usage in medical practice.

Reticulated Polyamide Thin-Film Nanocomposite Membranes Incorporated with 2D Boron Nitride Nanosheets for High-Performance Nanofiltration.

Nanofiltration (NF) technology has been widely used in saline wastewater treatment due to its unique separation mechanism. However, the NF membrane, as the core of the nanofiltration technology, is restricted by the trade-off between permeability and selectivity, which greatly restricts the development of NF membranes. The interlamellar arrangement of 2D boron nitride nanosheets (BNNSs) can provide additional transport channels and selectivity, as well as strong adsorption capacity due to its high specific surface area, exhibiting significant potential for advanced membranes. In this work, BNNSs prepared by tannic acid (TA)-assisted exfoliation (TA@BNNSs) were successfully adopted to fabricate thin-film nanocomposite (TFN) membranes via interfacial polymerization (IP). The resultant TFN membranes' structure and properties were systematically characterized via various methods. The results demonstrated that the surface morphology of polyamide membranes evolved gradually from a nodular structure to a reticular topography, accompanied by the decrease of the thickness of the polyamide selective layer when incorporating TA@BNNSs into the membranes. This phenomenon can be mainly ascribed to that the uptake density and diffusion of piperazine (PIP) monomer were effectively regulated by BNNSs. This is validated by molecular dynamics and revealed by the adsorption of PIP in BN models, the diffusion coefficients, and interaction energies, respectively. In addition, the TFN membranes demonstrated improved permeance and stable solute rejection for the inorganic salts. Specifically, the water flux of PA-TA@BNNSs-10%/PMIA membrane could reach up to 109.1 ± 2.49 L·m-2·h-1 while keeping a high rejection of 97.5 ± 0.38% to Na2SO4, which was superior to most of the reported membranes in the literature. Besides, the PA-TA@BNNSs-10%/PMIA membrane exhibited an excellent stability in the long-term filtration process. The finding in this work provides a potential strategy for developing the next-generation 2D material-based membranes with high-performance for separation applications.

Curcumin Alleviates Oxidative Stress, Neuroinflammation, and Promotes Behavioral Recovery After Traumatic Brain Injury.

BACKGROUND: Neuroinflammation and oxidative stress after traumatic brain injury (TBI) can further lead to neuronal apoptosis, which plays a crucial role in the process of neuron death. Curcumin, which is derived from the rhizome of the Curcuma longa plant, has multiple pharmacological effects. OBJECTIVE: The objective of this study was to investigate whether curcumin treatment has neuroprotective effects after TBI, and to elucidate the underlying mechanism. METHODS: A total of 124 mice were randomly divided into 4 groups: Sham group, TBI group, TBI+Vehicle group, and TBI+Curcumin group. The TBI mice model used in this study was constructed with TBI device induced by compressed gas, and 50 mg/kg curcumin was injected intraperitoneally 15 minutes after TBI. Then, the blood-brain barrier permeability, cerebral edema, oxidative stress, inflammation, apoptosis-related protein, and behavioral tests of neurological function were utilized to evaluate the protective effect of curcumin after TBI. RESULTS: Curcumin treatment markedly alleviated post-trauma cerebral edema and blood-brain barrier integrity, and suppressed neuronal apoptosis, reduced mitochondrial injury and the expression of apoptosis-related proteins. Moreover, curcumin also attenuates TBI-induced inflammatory response and oxidative stress in brain tissue and improves cognitive dysfunction after TBI. CONCLUSION: These data provide substantial evidence that curcumin has neuroprotective effects in animal TBI models, possibly through the inhibition of inflammatory response and oxidative stress.

Modulating Brain Activity with Invasive Brain-Computer Interface: A Narrative Review.

Brain-computer interface (BCI) can be used as a real-time bidirectional information gateway between the brain and machines. In particular, rapid progress in invasive BCI, propelled by recent developments in electrode materials, miniature and power-efficient electronics, and neural signal decoding technologies has attracted wide attention. In this review, we first introduce the concepts of neuronal signal decoding and encoding that are fundamental for information exchanges in BCI. Then, we review the history and recent advances in invasive BCI, particularly through studies using neural signals for controlling external devices on one hand, and modulating brain activity on the other hand. Specifically, regarding modulating brain activity, we focus on two types of techniques, applying electrical stimulation to cortical and deep brain tissues, respectively. Finally, we discuss the related ethical issues concerning the clinical application of this emerging technology.

Advanced water treatment process by simultaneous coupling granular activated carbon (GAC) and powdered carbon with ultrafiltration: Role of GAC particle shape and powdered carbon type.

In current ultrafiltration systems, limited removal for small-sized contaminants and membrane fouling remain longstanding obstacles to overcome. Herein, a novel process by simultaneous coupling powered carbon (PC) and fluidized granular activated carbon (GAC) with ultrafiltration was proposed aiming to achieve high effluent quality and mitigated membrane fouling. This study conducted mechanistic explorations on the performances of different-shaped GAC particles on fouling control and PC release during fluidization, meanwhile comparing the utilizations of powdered activated carbon (PAC) and biochar in terms of their adsorption, deposition and interactions with aquatic contaminants during filtration. The results showed that the effluent COD of biochar-UF was slightly higher than PAC-UF attributed to lower specific surface area and pore volume present on biochar. Compared with PAC-UF, the biochar-UF without fluidized GAC exhibited higher fouling propensity due to more organics attached on membranes via bridging with Ca2+ released by the biochar. Concurrently, distinct morphologies were found for PAC and biochar depositions, where PAC uniformly dispersed on membranes but biochar tended to agglomerate. Interestingly, fluidized spherical GAC (RGAC) with highest particle momentum and least energy consumption appeared highly effective in reducing fouling associated with biochar, and the overall fouling rate of RGAC-biochar-UF was even lower than RGAC-PAC-UF system. More importantly, substantial amount of small-sized PC was released by two cylindrical-shaped GACs, which were determined to be around 12-16 mg/L in contrast to merely 3.4 mg/L produced from RGAC. Consequently, the RGAC-biochar-UF system achieved commensurate effluent quality but better permeability than RGAC-PAC-UF along with a 20% expenditure saved, which might be a promising water treatment system more suitable for large-scale applications.

Microbial diversity of meat products under spoilage and its controlling approaches.

Meat spoilage (MS) is a complex microbial ecological process involving multiple specific microbial interactions. MS is detrimental to people's health and leads to the waste of meat products which caused huge losses during production, storage, transportation, and marketing. A thorough understanding of microorganisms related to MS and their controlling approaches is a necessary prerequisite for delaying the occurrence of MS and developing new methods and strategies for meat product preservation. This mini-review summarizes the diversity of spoilage microorganisms in livestock, poultry, and fish meat, and the approaches to inhibit MS. This would facilitate the targeted development of technologies against MS, to extend meat's shelf life, and effectively diminish food waste and economic losses.

Highly flexible and superhydrophobic MOF nanosheet membrane for ultrafast alcohol-water separation.

High-performance pervaporation membranes have potential in industrial separation applications, but overcoming the permeability-selectivity trade-off is a challenge. We report a strategy to create highly flexible metal-organic framework nanosheet (MOF-NS) membranes with a faveolate structure on polymer substrates for alcohol-water separation. The controlled growth followed by a surface-coating method effectively produced flexible and defect-free superhydrophobic MOF-NS membranes. The reversible deformation of the flexible MOF-NS and the vertical interlamellar pathways were captured with electron microscopy. Molecular simulations confirmed the structure and revealed transport mechanism. The ultrafast transport channels in MOF-NS exhibited an ultrahigh flux and a separation factor of 8.9 in the pervaporation of 5 weight % ethanol-water at 40°C, which can be used for biofuel recovery. MOF-NS and polydimethylsiloxane synergistically contribute to the separation performance.

GC-TOF-MS-Based Non-Targeted Metabolomic Analysis of Differential Metabolites in Chinese Ultra-Long-Term Industrially Fermented Kohlrabi and Their Associated Metabolic Pathways.

Fermented kohlrabi is a very popular side dish in China. Chinese kohlrabies industrially fermented for 0 years (0Y), 5 years (5Y), and 10 years (10Y) were employed and analyzed by non-targeted metabolomics based on GC-TOF-MS, and the differential metabolites were screened using multivariate statistical analysis techniques, including principal component analysis (PCA) and orthogonal partial least squares discrimination analysis (OPLS-DA). The results showed that 47, 38, and 33 differential metabolites were identified in the three treatment groups of 0Y and 5Y (A1), 0Y and 10Y (A2), and 5Y and 10Y (A3), respectively (VIP > 1, p < 0.05). The metabolites were mainly carbohydrates, amino acids, and organic acids. Furthermore, 13 differential metabolites were screened from the three groups, including L-glutamic acid, L-aspartic acid, γ-aminobutyric acid, and other compounds. Four metabolic pathways termed alanine, aspartate, and glutamate metabolism, arginine biosynthesis, arginine and proline metabolism, and glycolysis/gluconeogenesis were the most significant pathways correlated with the differential metabolites, as analyzed according to the Kyoto Encyclopedia of Genes and Genomes (KEGG). The odors for the three ultra-long-term industrially fermented kohlrabies were significantly different, as detected by E-nose. The present work describes the changes in metabolites between different ultra-long-term industrially fermented kohlrabies and the associated metabolic pathways, providing a theoretical basis for the targeted regulation of characteristic metabolite biosynthesis in Chinese fermented kohlrabi.

Characterization of Quality Properties in Spoiled Mianning Ham.

Deep spoilage is a cyclical and costly problem for the meat industry. Mianning ham is a famous dry-cured meat product in Sichuan, China. The aim of this work was to investigate the physicochemical characteristics, sources of odor, and associated microorganisms that cause spoilage of Mianning ham. High-throughput sequencing and solid-phase microextraction-gas-chromatography (SPME-GC-MS) techniques were used to characterize the physicochemical properties, microbial community structure, and volatile compounds of spoiled Mianning ham and to compare it with normal Mianning ham. The results showed that spoiled ham typically had higher moisture content, water activity (aw), and pH, and lower salt content. The dominant bacterial phylum detected in deeply spoiled ham was Firmicutes (95.4%). The dominant bacterial genus was Clostridium_sensu_stricto_2 (92.01%), the dominant fungal phylum was Ascomycota (98.48%), and the dominant fungal genus was Aspergillus (84.27%). A total of 57 volatile flavor substances were detected in deeply spoiled ham, including 11 aldehydes, 2 ketones, 6 alcohols, 10 esters, 20 hydrocarbons, 6 acids, and 2 other compounds. Hexanal (279.607 ± 127.265 µg/kg) was the most abundant in deeply spoiled ham, followed by Butanoic acid (266.885 ± 55.439 µg/kg) and Nonanal (165.079 ± 63.923 µg/kg). Clostridium_sensu_stricto_2 promoted the formation of five main flavor compounds, Heptanal, (E)-2-Octenal, 2-Nonanone, Hexanal, and Nonanal, in deeply spoiled ham by correlation analysis of microbial and volatile flavor substances.

Molecular simulations of the effects of substitutions on the dissolution properties of amorphous cellulose acetate.

The dissolution behavior of cellulose acetate (CA) is an extremely important property in its extensive applications and preparation of derivatives. In this paper, we proposed a molecular model building strategy to construct amorphous CA with various substituent distributions (different degrees of substitution and substitution positions). A protocol combing molecular dynamics simulation and density functional theory (DFT) was applied to systematically investigate the dissolution behavior of CAs, and the structural properties of CAs. The reduced cohesive energy and polarity of CAs caused by the increase in substituents would enhance its solubility. The interaction of solvent molecules and CAs and the diffusion of solvent molecules in CAs have a synergistic effect on the dissolution of CAs. The diffusion coefficient is the primary factor affecting the solubility. Moreover, substituents at different positions of the anhydroglucose units along the CAs chains would produce different steric hindrance effects, which in turn affect the dissolution behavior.

[Ecological Quality Assessment of the Wetlands in Beijing: Based on Plant Diversity].

Wetland plant diversity reveals key aspects of the environmental and ecological status of wetlands and plays an important role in the maintenance of ecosystem functions and services. The present study surveyed the plant species diversity of 22 wetlands in Beijing and, combining field data and remote sensing data, evaluated ecological qualities of the wetlands based on indicators of habitat status, plant species diversity, typical wetland plant community, and status of alien plant invasion. A total of 338 species (including varieties and subspecies) belonging to 220 genera of 74 families of wetland plants were recorded in Beijing. The wetlands could be divided into four types according to plant species composition, which showed a spatial gradient pattern from urban core to ecological conservation areas. Wetlands located in ecological conservation areas were of better ecological quality than those located in urban core and suburban plain areas. The value of ecological quality index (EQI) for Baihe River, Huaishahe-Huaijiuhe River, Jinniu Lake, Hanshiqiao Wetland, and Yongdinghe River (Mentougou Section) were in the top five, whereas the value of EQI for river-type wetlands located in suburban plain areas were relatively lower. The results of the canonical correspondence analysis indicated that the most critical factors affecting wetland plant species composition were the distance to the nearest road, water total nitrogen, and area percentage of ecological green land. Furthermore, the results of the canonical correlation analysis indicated that the most critical factors affecting wetland plant species diversity were the area percentage of construction land and water total organic carbon. Human activity intensity and water quality have a strong impact on the plant diversity and ecological quality of wetlands in Beijing. It is suggested that efforts should be made to strengthen the ecological protection and restoration of the river-type wetlands located in suburban plain areas.

An Artificial Pathway for N-Hydroxy-Pipecolic Acid Production From L-Lysine in Escherichia coli.

N-hydroxy-pipecolic acid (NHP) is a hydroxylated product of pipecolic acid and an important systemic acquired resistance signal molecule. However, the biosynthesis of NHP does not have a natural metabolic pathway in microorganisms. Here, we designed and constructed a promising artificial pathway in Escherichia coli for the first time to produce NHP from biomass-derived lysine. This biosynthesis route expands the lysine catabolism pathway and employs six enzymes to sequentially convert lysine into NHP. This artificial route involves six functional enzyme coexpression: lysine α-oxidase from Scomber japonicus (RaiP), glucose dehydrogenase from Bacillus subtilis (GDH), Δ1-piperideine-2-carboxylase reductase from Pseudomonas putida (DpkA), lysine permease from E. coli (LysP), flavin-dependent monooxygenase (FMO1), and catalase from E. coli (KatE). Moreover, different FMO1s are used to evaluate the performance of the produce NHP. A titer of 111.06 mg/L of NHP was yielded in shake flasks with minimal medium containing 4 g/L of lysine. By this approach, NHP has so far been produced at final titers reaching 326.42 mg/L by 48 h in a 5-L bioreactor. To the best of our knowledge, this is the first NHP process using E. coli and the first process to directly synthesize NHP by microorganisms. This study lays the foundation for the development and utilization of renewable resources to produce NHP in microorganisms.

Effects of the Local Bone Renin-Angiotensin System on Titanium-Particle-Induced Periprosthetic Osteolysis.

Wear particles may induce osteoclast formation and osteoblast inhibition that lead to periprosthetic osteolysis (PPOL) and subsequent aseptic loosening, which is the primary reason for total joint arthroplasty failure. Local bone renin-angiotensin system (RAS) has been found to participate in the pathogenic process of various bone-related diseases via promoting bone resorption and inhibiting bone formation. However, it remains unclear whether and how local bone RAS participates in wear-particle-induced PPOL. In this study, we investigated the potential role of RAS in titanium (Ti) particle-induced osteolysis in vivo and osteoclast and osteoblast differentiation in vitro. We found that the expressions of AT1R, AT2R and ACE in the interface membrane from patients with PPOL and in calvarial tissues from a murine model of Ti-particle-induced osteolysis were up-regulated, but the increase of ACE in the calvarial tissues was abrogated by perindopril. Moreover, perindopril mitigated the Ti-particle-induced osteolysis in the murine model by suppressing bone resorption and increasing bone formation. We also observed in RAW264.7 macrophages that Ang II promoted but perindopril suppressed Ti-particle-induced osteoclastogenesis, osteoclast-mediated bone resorption and expression of osteoclast-related genes. Meanwhile, Ang II enhanced but perindopril repressed Ti-particle-induced suppression of osteogenic differentiation and expression of osteoblast-specific genes in mouse bone marrow mesenchymal stem cells (BMSCs). In addition, local bone RAS promoted Ti-particle-induced osteolysis by increasing bone resorption and decreasing bone formation through modulating the RANKL/RANK and Wnt/ß-catenin pathways. Taken together, we suggest that inhibition of RAS may be a potential approach to the treatment of wear-particle-induced PPOL.

A Review: Microbial Diversity and Function of Fermented Meat Products in China.

Fermented meat products have a long history in China. These products exhibit a characteristic unique flavor, compact meat quality, clear color, long shelf life and wide variety and are easy to transport. During the processing and storage of fermented meat products, microorganisms are present and exhibit diverse characteristics. Microorganisms can accelerate the degradation of proteins and fats to produce flavor compounds, inhibit the growth and reproduction of heterozygous bacteria, and reduce the content of chemical pollutants. This paper reviews the microbial diversity of Chinese ham, sausage, preserved meat, pressed salted duck, preserved fish and air-dried meat and provides analyses of the microbial compositions of various products. Due to the differences in raw materials, technology, auxiliary materials, and fermentation technology, the microbial species found in various fermented meat products in China are different. However, most fermented meat products in China are subjected to pickling and fermentation, so their microbial compositions also have similarities. Microorganisms in fermented meat products mainly include staphylococci, lactobacilli, micrococci, yeasts, and molds. The study of microbial diversity is of great significance for the formation of quality flavor and the safety control of fermented meat products, and it provides some theoretical reference for the study of fermented meat products in China.

Establishment and Evaluation of a Novel High-Efficiency Model of Graded Traumatic Brain Injury in Mice.

BACKGROUND: Although previous studies have made significant contributions to establishing animal traumatic brain injury (TBI) models for simulation of human TBI, the accuracy, controllability, and modeling efficiency of animal TBI models need to be further improved. This study established a novel high-efficiency graded mouse TBI model induced by shock wave. METHODS: A total of 125 mice were randomly divided into sham, 0.7 mm, 0.6 mm, and 0.5 mm groups according to the depth of the cross groove of the aluminum sheets. The stability and repeatability of apparatus were evaluated, and the integrity of the blood-brain barrier, cerebral edema, neuropathologic immunohistochemistry, apoptosis-related protein, and behavioral tests of neurologic function were used to validate this new model. RESULTS: The results showed that 4 mice were injured simultaneously in 1 experiment. They received the same intensity of shock waves. Moreover, the mortality rates caused by 3 different aluminum sheets were consistent with the mortality rates of mild TBI, moderate TBI, and severe TBI. Compared with the sham group, mice in different injured groups significantly increased brain water content, blood-brain barrier permeability, and neuronal apoptosis. And the mice in all injured groups showed poor motor ability, balancing, spatial learning, and memory abilities. CONCLUSIONS: The novel TBI apparatus has advantages in its small size, simple operation, high repeatability, high efficiency, and graded severity. Our TBI apparatus provides a novel tool to investigate the neuropathologic changes and underlying mechanisms of TBI with various levels of severities.