Relationship between serum apolipoprotein B and risk of all-cause and cardiovascular disease mortality in individuals with hypertension: a prospective cohort study.

BACKGROUND: Dyslipidemia frequently coexists with hypertension in the population. Apolipoprotein B (ApoB) is increasingly considered a more potent predictor of cardiovascular disease (CVD). Abnormal levels of serum ApoB can potentially impact the mortality risk. METHODS: The prospective cohort study employed data from the National Health and Nutrition Examination Survey (NHANES), which was performed between 2005 and 2016, with follow-ups extended until December 2019. Serum ApoB concentrations were quantified using nephelometry. In line with the NHANES descriptions and recommendations, the reference ranges for ApoB concentrations are 55-140 and 55-125 mg/dL for men and women, respectively. Participants were categorized into low, normal, and high ApoB levels. The low and high groups were combined into the abnormal group. In this study, all-cause mortality (ACM) and CVD mortality (CVM) were the endpoints. Survey-weighted cox hazards models were used for evaluating the correlation between serum ApoB levels and ACM and CVM. A generalized additive model (GAM) was employed to examine the dose-dependent relationship between ApoB levels and mortality risk. RESULTS: After a median of 95 (interquartile range: 62-135) months of follow-up, 986 all-cause and 286 CVD deaths were recorded. The abnormal ApoB group exhibited a trend toward an elevated risk of ACM in relative to the normal group (HR 1.22, 95% CI: 0.96-1.53). The risk of CVM was elevated by 76% in the ApoB abnormal group (HR 1.76, 95% CI: 1.28-2.42). According to the GAM, there existed a nonlinear association between serum ApoB levels and ACM (P = 0.005) and CVM (P = 0.009). CONCLUSIONS: In the US hypertensive population, serum Apo B levels were U-shaped and correlated with ACM and CVM risk, with the lowest risk at 100 mg/dL. Importantly, abnormal Apo B levels were related to an elevated risk of ACM and CVM. These risks were especially high at lower Apo B levels. The obtained findings emphasize the importance of maintaining appropriate Apo B levels to prevent adverse outcomes in hypertensive individuals.

Superior predictive value of estimated pulse wave velocity for all-cause and cardiovascular disease mortality risk in U.S. general adults.

BACKGROUND: Estimated pulse wave velocity (ePWV) has been proposed as a potential approach to estimate carotid-femoral pulse wave velocity. However, the potential of ePWV in predicting all-cause mortality (ACM) and cardiovascular disease mortality (CVM) in the general population is unclear. METHODS: We conducted a prospective cohort study using the data of 33,930 adults (age ≥ 20 years) from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2014 until the end of December 2019. The study outcomes included ACM and CVM. Survey-weighted Cox proportional hazards models were used to assess hazard ratios (HRs) and 95% confidence intervals (CIs) to determine the association between ePWV and ACM and CVM. To further investigate whether ePWV was superior to traditional risk factors in predicting ACM and CVM, comparisons between ePWV and the Framingham Risk Score (FRS) and Pooled Cohort Equations (PCE) models were performed. Integrated Discriminant Improvement (IDI) and Net Reclassification Improvement (NRI) were employed to analyze differences in predictive ability between models. RESULTS: The weighted mean age of the 33,930 adults included was 45.2 years, and 50.28% of all participants were men. In the fully adjusted Cox regression model, each 1 m/s increase in ePWV was associated with 50% and 49% increases in the risk of ACM (HR 1.50; 95% CI, 1.45-1.54) and CVM (HR 1.49; 95% CI, 1.41-1.57), respectively. After adjusting for FRS, each 1 m/s increase in ePWV was still associated with 29% (HR 1.29; 95% CI, 1.24-1.34) and 34% (HR 1.34; 95% CI, 1.23-1.45) increases in the risk of ACM and CVM, respectively. The area under the curve (AUC) predicted by ePWV for 10-year ACM and CVM were 0.822 and 0.835, respectively. Compared with the FRS model, the ePWV model improved the predictive value of ACM and CVM by 5.1% and 3.8%, respectively, with no further improvement in event classification. In comparison with the PCE model, the ePWV model's ability to predict 10-year ACM and CVM was improved by 5.1% and 3.5%, and event classification improvement was improved by 34.5% and 37.4%. CONCLUSIONS: In the U.S. adults, ePWV is an independent risk factor for ACM and CVM and is independent of traditional risk factors. In the general population aged 20 to 85 years, ePWV has a robust predictive value for the risk of ACM and CVM, superior to the FRS and PCE models. The predictive power of ePWV likely originates from the traditional risk factors incorporated into its calculation, rather than from an indirect association with measured pulse wave velocity.

Higher systemic immune-inflammation index and systemic inflammation response index levels are associated with stroke prevalence in the asthmatic population: a cross-sectional analysis of the NHANES 1999-2018.

Background: Significant evidence suggests that asthma might originate from low-grade systemic inflammation. Previous studies have established a positive association between the systemic immune-inflammation index (SII) and the systemic inflammation response index (SIRI) levels and the risk of stroke. However, it remains unclear whether SII, SIRI and the prevalence of stroke are related in individuals with asthma. Methods: The present cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) conducted between 1999 and 2018. SII was calculated using the following formula: (platelet count × neutrophil count)/lymphocyte count. SIRI was calculated using the following formula: (neutrophil count × monocyte count)/lymphocyte count. The Spearman rank correlation coefficient was used to determine any correlation between SII, SIRI, and the baseline characteristics. Survey-weighted logistic regression was employed to calculate odds ratios (ORs) and 95% confidence intervals (CIs) to determine the association between SII, SIRI, and stroke prevalence. The predictive value of SII and SIRI for stroke prevalence was assessed through receiver operating characteristic (ROC) curve analysis, with the area under the ROC curve (AUC) being indicative of its predictive value. Additionally, clinical models including SIRI, coronary heart disease, hypertension, age, and poverty income ratio were constructed to evaluate their clinical applicability. Results: Between 1999 and 2018, 5,907 NHANES participants with asthma were identified, of which 199 participants experienced a stroke, while the remaining 5,708 participants had not. Spearman rank correlation analysis indicated that neither SII nor SIRI levels exhibited any significant correlation with the baseline characteristics of the participants (r<0.1). ROC curves were used to determine the optimal cut-off values for SII and SIRI levels to classify participants into low- and high-level groups. Higher SII and SIRI levels were associated with a higher prevalence of stroke, with ORs of 1.80 (95% CI, 1.18-2.76) and 2.23 (95% CI, 1.39-3.57), respectively. The predictive value of SIRI (AUC=0.618) for stroke prevalence was superior to that of SII (AUC=0.552). Furthermore, the clinical model demonstrated good predictive value (AUC=0.825), with a sensitivity of 67.1% and specificity of 87.7%. Conclusion: In asthmatics, higher levels of SII and SIRI significantly increased the prevalence of stroke, with its association being more pronounced in individuals with coexisting obesity and hyperlipidaemia. SII and SIRI are relatively stable novel inflammatory markers in the asthmatic population, with SIRI having a better predictive value for stroke prevalence than SII.

Estimated pulse wave velocity is associated with all-cause and cardio-cerebrovascular disease mortality in stroke population: Results from NHANES (2003-2014).

Background: Arterial stiffness is a significant determinant and evaluation of cardio-cerebrovascular disease and all-cause mortality risk in the stroke population. Estimated pulse wave velocity (ePWV) is a well-established indirect measure of arterial stiffness. We examined the association of ePWV with all-cause and cardio-cerebrovascular disease (CCD) mortality in the stroke population in a large sample of US adults. Methods: The study design was a prospective cohort study with data from the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2014, between the ages of 18-85 years, with follow-up through December 31, 2019. 1,316 individuals with stroke among 58,759 participants were identified and ultimately, 879 stroke patients were included in the analysis. ePWV was calculated from a regression equation using age and mean blood pressure according to the following formula: ePWV = 9.587 - (0.402 × age) + [4.560 × 0.001 × (age2)] - [2.621 × 0.00001 × (age2) × MBP] + (3.176 × 0.001 × age × MBP) - (1.832 × 0.01 × MBP). Survey-weighted Cox regression models were used to assess the association between ePWV and all-cause and CCD mortality risk. Results: The high ePWV level group had a higher increased risk of all-cause mortality and CCD mortality compared to the low ePWV level group after fully adjusting for covariates. With an increase in ePWV of 1 m/s, the risk of all-cause and CCD mortality increased by 44%-57% and 47%-72% respectively. ePWV levels were linearly correlated with the risk of all-cause mortality (P for nonlinear = 0.187). With each 1 m/s increase in ePWV, the risk of all-cause mortality increased by 44% (HR 1.44, 95% CI: 1.22-1.69; P < 0.001). When ePWV was <12.1 m/s, an increase in ePWV per 1 m/s was associated with a 119% (HR 2.19, 95% CI: 1.43-3.36; P < 0.001) increase in CCD mortality risk; when ePWV was ≥12.1 m/s, an increase in ePWV per 1 m/s was not associated with in CCD mortality risk. Conclusion: ePWV is an independent risk factor for all-cause and CCD mortality in stroke patients. Higher levels of ePWV are associated with higher all-cause mortality and CCD mortality in stroke patients.

Alternate-day fasting exacerbates doxorubicin cardiotoxicity in cancer chemotherapy.

Doxorubicin (Dox) is a highly potent chemotherapy drug. Despite its efficacy, Dox's clinical application is limited due to its association with significant complications, namely cardiotoxicity and the risk of heart failure. Recent intriguing findings by Ozcan et al. indicate that alternate-day fasting (ADF) significantly exacerbates the cardiotoxicity of Dox.

Association of arterial stiffness with all-cause and cause-specific mortality in the diabetic population: A national cohort study.

Background: Estimated pulse wave velocity (ePWV) has been proposed as a potential alternative to carotid-femoral pulse wave velocity to assess the degree of aortic stiffness, and may predict cardiovascular disease (CVD) outcomes and mortality in the general population. However, whether arterial stiffness estimated by ePWV predicts all-cause and cause-specific mortality in patients with diabetes mellitus (DM) has not been reported. Methods: This was a prospective cohort study with data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2014 and followed up until the end of December 2019. 5,235U.S. adults with DM (age≥20years) were included in the study. Arterial stiffness was estimated by ePWV. Survey-weighted Cox proportional hazards models were performed to assess the hazard ratios (HRs), and 95% confidence intervals (CIs) for the associations of ePWV with all-cause and cause-specific mortality. Meanwhile, the generalized additive model was used to visually assess the dose-dependent relationship between ePWV and mortality. As a complementary analysis, the relationship between mean blood pressure (MBP) and risk of mortality was also examined. Multiple imputations accounted for missing data. Results: For the 5,235 DM patients, the weighted mean age was 57.4 years, and 51.07% were male. During a median follow-up period of 115 months (interquartile range 81-155 months; 53,159 person-years), 1,604 all-cause deaths were recorded. In the fully adjusted Cox regression model, every 1 m/s increase in ePWV was associated with 56% (HR 1.56; 95% CI, 1.44 to 1.69) increase in the risk of all-cause. In addition, a nonlinear relationship between ePWV and all-cause mortality was observed (P for non-linear=0.033). Similar results were obtained after subgroup analysis and multiple imputations. Besides, the risk of most cause-specific mortality, except for accident and renal disease-specific mortality, increased from 53% to 102% for every 1 m/s increase in ePWV. Conclusions: In the diabetic population, ePWV is independently associated with all-cause and most cause-specific mortality risks. ePWV may be a useful tool for assessing mortality risk.

Thiram-induced hyperglycemia causes tibial dyschondroplasia by triggering aberrant ECM remodeling via the gut-pancreas axis in broiler chickens.

Pesticide thiram is widely used in agriculture and has been demonstrated to cause tibial dyschondroplasia (TD) in birds. However, the underlying mechanism remains unclear. This work used multi-omics analysis to evaluate the molecular pathways of TD in broilers that were exposed to low level of thiram. Integrative analysis of transcriptomic, proteomic, and metabolomic revealed thiram activity in enhancing pathological ECM remodeling via attenuating the glycolysis pathway and activating the hexosamine and glucuronic acid pathways. Intriguingly, we found hyperglycemia as a crucial factor for ECM overproduction, which resulted in the development of TD. We further demonstrated that high glucose levels are caused by islet secretion dysfunction in thiram-treated broilers. A combination of factors, including lipid disorder, low-grade inflammation, and gut flora disturbance, might contribute to the dysregulation of insulin secretion. The current work revealed the underlying toxicological mechanisms of thiram-induced tibial dyschondroplasia through blood glucose disorder via the gut-pancreas axis in chickens for the first time, which makes it easier to figure out the health risks of pesticides for worldwide policy decisions.

Thiram induces myocardial oxidative damage and apoptosis in broilers via interfering their cardiac metabolism.

Thiram is a dithiocarbamate pesticide extensively used as a fungicide to preserve crops and seeds. Long-term exposure to thiram causes potential harm to the health of human beings and animals. So far, most of the researches on thiram focused on erythrocyte toxicity, immune system, kidney damage, and tibial dyschondroplasia; however, there is less data on cardiac toxicity. In this study, we examined cardiac histopathology, inflammatory factors, oxidative stress indicators, and apoptosis markers in the heart of broilers that were exposed to thiram. According to our findings, the continuous exposure to thiram caused pathological changes and abnormal function of myocardial tissues with increased level of inducible nitric oxide synthase (iNOS), inflammatory factors (IL-6, IL-8, TNF-α and NF-κB), and decreased level of anti-inflammatory factor (IL-10). In addition, thiram significantly upregulated the protein expression of cleaved-caspase 3, cleaved-PARP, and caused cardiomyocyte apoptosis. Meanwhile, the expression of heat shock proteins (HSP60, HSP70, HSP90) markedly decreased in the thiram-treated groups. An excessive accumulation of peroxidation products (MDA, H2O2), a decrease in T-AOC, and antioxidant activity enzymes (T-SOD, GST and GPX) were also noticed, all of which led to oxidative stress and activation of Nrf2 signal pathway by up-regulating key target genes (HO-1 and SODs). Thiram-induced metabolites were further identified via non-targeted metabonomic analysis. Correlation analysis revealed eighteen differentially expressed metabolites, closely related to cardiac injury. Importantly, thiram primarily affected the taurine and hypotaurine metabolism, pyrimidine metabolism as well as glycerol metabolism. Collectively, our study suggests that thiram could cause cardiotoxicity by interfering with taurine and hypotaurine metabolism, pyrimidine metabolism, and glycerolipid metabolism, which further induce oxidative stress via triggering Nrf2 signal pathway. This study may provide new evidence for the molecular mechanism of cardiotoxicity caused by thiram and resonate the alarm for animals and workers who have been exposed to thiram for a long time.

Regulatory Role of Apoptotic and Inflammasome Related Proteins and Their Possible Functional Aspect in Thiram Associated Tibial Dyschondroplasia of Poultry.

Tibial dyschondroplasia debilities apoptotic and inflammasomal conditions that can further destroy chondrocytes. Inflammasomes are specialized protein complexes that process pro-inflammatory cytokines, e.g., interleukin-1ß (IL-1ß) and IL-18. Moreover, there is mounting evidence that many of the signaling molecules that govern programmed cell death also affect inflammasome activation in a cell-intrinsic way. During the last decade, apoptotic functions have been described for signaling molecules involving inflammatory responses and cell death pathways. Considering these exceptional developments in the knowledge of processes, this review gives a glimpse of the significance of these two pathways and their connected proteins in tibial dyschondroplasia. The current review deeply elaborates on the elevated level of signaling mediators of mitochondrial-mediated apoptosis and the inflammasome. Although investigating these pathways' mechanisms has made significant progress, this review identifies areas where more study is especially required. It might lead to developing innovative therapeutics for tibial dyschondroplasia and other associated bone disorders, e.g., osteoporosis and osteoarthritis, where apoptosis and inflammasome are the significant pathways.

Chlorogenic acid suppresses miR-460a in the regulation of Bcl-2, causing interleukin-1ß reduction in thiram exposed chondrocytes via caspase-3/caspase-7 pathway.

BACKGROUND: Apoptosis is thought to be involved in all processes, including normal cell cycle, immune system, atrophy, embryonic development, and chemical-induced cellular damage. However, if the normal apoptotic process fails, the results might be disastrous, e.g., chondrocytes damage in tibial dyschondroplasia (TD). TD is a worldwide issue in the poultry sector due to thiram toxicity. Thiram (Tetramethyl thiuram disulfide) is a dithiocarbamate pesticide and fungicide commonly used in horticulture to treat grains meant for seed protection and preservation. PURPOSE: According to prior studies, chlorogenic acid (CGA) is becoming essential for regulating apoptosis. But still, the specific role of CGA in chondrocyte cells remains unclear. The present study explored the molecular mechanism of CGA on chondrocytes' apoptosis with B-cell lymphoma 2 signaling under the effect of miR-460a. METHODS: An in vivo and in vitro study was performed according to our previously developed methodology. Flow cytometry, western blotting, reverse transcription-quantitative polymerase chain reaction, and immunofluorescence assay were used to investigate the involvement of apoptosis and inflammasome related pathways. RESULTS: The CGA decreased the apoptosis rate with the deactivation of miR-460a, accompanied by the activation of Bcl-2. The high expression of miR-460a reduced the cell viability of chondrocytes in vitro and in vivo, that led to the interleukin-1ß production. While the apoptotic executioners (caspase-3 and caspase-7) acted upstream in miR-460a overexpressing cells, and its depletion downgraded these executioners. The CGA administrated cells negatively regulated miR-460a expression and thus indicating the deactivation of the apoptotic and inflammasome related pathways. CONCLUSION: Chlorogenic acid had a negative effect on miR-460a, setting off specific feedback to regulate apoptotic and inflammasome pathways, which might be a key feature for chondrocytes' survival.

Effects of Bacillus amyloliquefaciens TL106 Isolated from Tibetan Pigs on Probiotic Potential and Intestinal Microbes in Weaned Piglets.

Bacillus amyloliquefaciens is a nonpathogenic microorganism whose highly active amylase is widely isolated from soil and plants. TL106 is an isolate of Bacillus amyloliquefaciens isolated from cold- and disease-resistant Tibetan pigs in Linzhi, Tibet. Here, we report that TL106 not only could survive in acidic environments, high bile salt concentrations, and high-temperature conditions but also was resistant to antibiotics. It significantly improved the growth performance of weaned piglets, especially in the prevention of diarrhea. The crude fiber and crude ash digestibility in weaned piglets after TL106 administration was considerably higher than that in other groups. The results of 16S rRNA sequencing conveyed that TL106 stabilized gut microbiota that was disturbed by the weaning process with an increased level of Lachnospiraceae, Peptococcaceae.rc4_4, Erysipelotrichaceae.L7A_E11, and Mollicutes.RF39. Hence, this study proved that Bacillus amyloliquefaciens TL106 might be a candidate for antibiotics in Duroc×Landrace×Yorkshire weaned piglets. IMPORTANCE Antibiotics are often used to promote animal growth and prevent diarrhea in weanling piglets. Nevertheless, intestinal pathogenic bacterial resistance and drug residues caused by antibiotic overuse are worthy of concern and demand an urgent solution. Bacillus amyloliquefaciens TL106 has been isolated from cold- and disease-resistant Tibetan pigs in Linzhi, Tibet. It significantly improved the growth performance, decreased diarrhea, increased the absorption of crude substances, and regulated the gut flora homeostasis in Duroc×Landrace×Yorkshire weaned piglets. As an antibiotic candidate, TL106 perfectly displayed its probiotic potential and pollution-free properties.

Chlorogenic acid suppresses mitochondrial apoptotic effectors Bax/Bak to counteract Nod-like receptor pyrin domain 3 (NLRP3) inflammasome in thiram exposed chondrocytes.

BACKGROUND: Tibial dyschondroplasia (TD) is a common disease characterized by proliferation and the deterioration of growth plate's chondrocytes due to widespread utilization of thiram in the agriculture and industrial sector. PURPOSE: In recent years, Nod-like receptor pyrin domain 3 (NLRP3) inflammasome has become a dilemma in the occurrence of many diseases. According to many research investigations, NLRP3 inflammasome has been linked to various diseases caused by pesticides and environmental toxins. Its involvement in such conditions opens up new treatment approaches. However, the role of the NLRP3 inflammasome in the development of TD is not fully understood under the impact of chlorogenic acid (CGA). METHODS: Chondrocytes were cultured with our previously developed methodology from growth plates. After morphological and molecular identification, chondrocytes were split into different groups to investigate the efficacy of chlorogenic acid. Cell apoptosis was determined through flow cytometry and Tunnel assay. Furthermore, RT-qPCR, immunofluorescence, and western blotting techniques were used to check marker genes and proteins expression. RESULTS: In thiram-induced TD, Bax/Bak activation persuade a parallel pathway, mediated by the NLRP3 base inflammasome. It is worth mentioning that the apoptotic executioners (caspase-3 and caspase-7) act upstream for inflammasome. Furthermore, chondrocytes' ability to undergo mitochondrial apoptosis was governed by anti-apoptotic members, e.g., Bcl-2 and Bcl-xl. Equilibrium of these anti-apoptotic proteins ensured appropriate regulation of apoptosis during the development and survival of chondrocytes. CONCLUSION: Chondrocytes have ability to undergo Bax/Bak-mediated apoptosis and generate pro-inflammatory signals, e.g., NLRP3 in thiram-induced TD. So, the Nod-like receptor pyrin domain 3 is the potential target to eliminate TD at all stages of pathology, while drugs, e.g., CGA, can significantly improve chondrocytes' survival by targeting these pro-inflammatory signals.

Complete genome analysis of Lactobacillus fermentum YLF016 and its probiotic characteristics.

Lactobacillus fermentum (L. fermentum) YLF016 is a well-characterized probiotic with several favorable characteristics. This study aimed to analyze the probiotic characteristics of L. fermentum and uncover the genes implicated in its potential probiotic ability on the base of its genomics features. The complete genome of L. fermentum YLF016 was found to have a circular chromosome of 2,094,354 bp, and 51.46% G + C content without any plasmid. Its chromosome contained 2,130 predicted protein-encoding genes, 58 tRNA, and 15 rRNA-encoding genes. Also, it was found to have many other probiotic properties, such as a high survival rate in the gastrointestinal tract with strong adherence to intestinal cells, antibacterial activity against pathogens, and antioxidant activity. Moreover, the genome sequence analysis demonstrated specific genes coding for carbon metabolism pathway, genetic adaption, stress resistance, and adhesive ability. Further analysis revealed its non-hemolytic activity and its non-functional ability of virulence factors. In conclusion, L. fermentum YLF016 possesses many valuable probiotic properties that refer to its potential probiotic ability.

Taurine is an effective therapy against thiram induced tibial dyschondroplasia via HIF-1α/VEGFA and ß-catenin/ GSK-3ß pathways in broilers.

Thiram causes tibial dyschondroplasia in broilers, leading to a significant economic loss in the poultry industry. Our study explored the effects of taurine in thiram induced tibial dyschondroplasia (TD) through in vivo and in vitro approches. In in vivo study, thiram resulted in lameness disorder, low production parameters ALP, ACP, and a high level of NOS. While, the taurine exhibited promising effect by reducing lameness, increasing ALP, ACP levels, and significantly lowering NOS level with the restoration of the growth plate. In in vitro study, thiram caused distortion and disintegration of chondrocytes. The CCK-8 technique revealed the lower cell activity in TD as compared with the treatment group. Even, the treatment and taurine groups had higher cell activity than control group. Also, the chondrocyte morphology progressively reverted to normal after taurine treatment. It might effectively decreased the symptoms of TD in broilers and their production performance. Further research found that the taurine effectively improved chondrocytes' cell viability and recovered lameness disorder by regulation of HIF-1α, VEGFA, and Wnt/ß-catenin signaling pathways. In summary, these results indicate that taurine has a protective effect on thiram-induced broilers and it can enhance the growth activity by directly affecting the development of chondrocytes and blood vessels.

Epidemiological Survey of Mycoplasma bovis in Yaks on the Qinghai Tibetan Plateau, China.

Mycoplasma bovis (M. bovis) is one of the most important pneumonia pathogens in yaks. It may result in more economic losses due to the cold and anoxia condition at Qinghai Tibetan plateau. However, to date, limited information on M. bovis infection in yaks is available in China. For this purpose, the seroprevalence of M. bovis was investigated in yaks living in the mentioned area through commercial ELISA kits. A total of 959 yaks were incorporated into this study. The prevalence of the disease in yaks was 48.70%. The serological results revealed a relatively high prevalence of M. bovis infection in yaks. The present study may greatly contribute to the prevention of this disease. More importance should be given to the potential threat caused by M. bovis in the special plateau.

Probiotic potential and safety assessment of Lactobacillus isolated from yaks.

Current problem of antibiotic resistance and the high incidence of bacterial diseases has brought huge losses to the yak breeding industry in Tibet. Therefore, the purpose of this study was to isolate Lactobacillus with safety and beneficial probiotic potential for the prophylaxis of intestinal diseases in yaks. After 16S rDNA sequence, four strains i.e. Lactobacillus sakei (named L4), Enterococcus hirae (named E5), Pediococcus acidilactici (named P7), Weissella confusa (named W8) were isolated from feces of yaks. The results of tolerance to acid, bile salt, enzyme and temperature showed that P7 was highly tolerant to acid, bile salt and digestive enzyme, while E5 was more resistant to temperature. The antibacterial assay showed L4 had a strong inhibitory effect against Staphylococcus aureus (BNCC186335), and E5, P7, W8 had effective antibacterial ability against Escherichia coli (C83902). In addition, L4, E5, P7 and W8 mainly produced organic acids and bacteriocin production to inhibit common intestinal pathogens. The results of antibiotic susceptibility assay indicated that L4, E5, P7 and W8 were highly sensitive to most clinically used antibiotics and didn't contain the VanA and VanB genes on the basis of PCR amplification, and L4, E5, P7 and W8 didn't exhibit hemolytic activity. The animal toxicity experiment results showed that no obvious pathological change was found in intestinal tissue sections, and L4, E5 and W8 strains also promoted the growth performance of mice, consequently, the L4, E5, P7 and W8 had no toxic effect on mice. In conclusion, lactobacillus isolated from feces of yaks not only have potential probiotics and strong antibacterial ability in vitro, but also are safe. Therefore, they have the potential to reduce the occurrence of bacterial diseases as new feed additives.