The expressions of miR-151a-5p and miR-23b in lung cancer tissues and their effects on the biological functions of lung cancer A549 cells

OBJECTIVE

To investigate the expressions of miR-151a-5p and miR-23b in lung cancer tissues and their effects on the biological functions of lung cancer A549 cells.

PATIENTS AND METHODS

Samples of lung cancer tissue (55 cases) and pericarcinomatous tissue (55 cases) were collected in thoracic surgery in our hospital from May 2017 to November 2018. The expression levels of miR-151a-5p and miR-23b in lung cancer tissues and pericarcinomatous tissues were detected by RT-PCR. Lung cancer cells A549 were transfected. Before transfection, the cells were divided into a negative control group (NC group, transfected with miRNA NC), a group transfected with miR-151a-5p inhibitor and a group transfected with miR-23b inhibitor. MTS Cell Proliferation Colorimetric Assay Kit (CCK8) was used to detect cell proliferation and draw the growth curve. Transwell chamber was used to detect the invasion ability in vitro, and BD flow cytometry was used to detect apoptosis in each group.

RESULTS

The expression levels of miR-151a-5p and miR-23b in lung cancer tissues were significantly higher than those in pericarcinomatous tissues (p<0.001). After 48 h to 72 h, the cell growth of both the miR-151a-5p inhibitor group and the miR-23b inhibitor group was significantly lower than that of the NC group (p<0.001). The numbers of invasion of miR-151a-5p inhibitor group and miR-23b inhibitor group were significantly lower than that of NC group (p<0.00). The apoptosis rates of miR-151a-5p inhibitor group and miR-23b inhibitor group were significantly higher than that of NC group (p<0.001).

CONCLUSIONS

Both miR-151a-5p and miR-23b are highly expressed in lung cancer, and the inhibition of miR-151a-5p and miR-23b can restrain the proliferation, invasion and migration of lung cancer A549 cells, thereby promoting the apoptosis of lung cancer A549 cells.

[Effect of RNA interference targeting neuropilin-2 gene on proliferation and apoptosis of colon cancer cell line HCT-8]

Objective: To investigate the effects of down-regulation of expression of neuropilin-2 (NRP-2) by RNA interference (RNAi) technique on proliferation and apoptosis of HCT-8 colon cancer cells. Methods: NRP2-siRNA and negative control (NControl)-siRNA were transferred into HCT-8 colon cancer cells by liposomes (lip2000) as transfection group and negative control group, and phosphate buffered solution (PBS) was added as blank control group. Quantitative reverse transcription PCR (RT-qPCR) and Western blot were used to detect the transfection effect. The proliferation of cells in the three groups was examined by cell counting kit (CCK) assay, colony-forming unit assay and Ki-67 protein staining assay, respectively. Moreover, the apoptosis of cells in the three groups was determined by acridine orange/propranidine iodide (AO/PI) staining method. Results: The results of RT-qPCR and Western blot showed that the relative expression of NRP-2 mRNA and the content of NRP-2 protein in the transfer group decreased (0.46±0.05 vs 0.99±0.05 and 1.00±0.06; 1.04±0.06 vs 1.73±0.09 and 1.65±0.11) (all P<0.05). The results of CCK-8 demonstrated that the optical density of transfection group was significantly lower than that of the negative control group and the blank control group(24 h: 0.53±0.04 vs 0.82±0.07 and 0.87±0.07; 48 h: 0.54±0.05 vs 1.00±0.09 and 1.17±0.05; 72 h: 0.75±0.05 vs 1.31±0.13 and 1.50±0.03; 96 h:1.05±0.04 vs 1.46±0.09 and 1.86±0.06) (all P<0.05). The results of colony-forming unit assay indicated that the proliferation ability of the cells in the transfer group was significantly lower than that in the other two groups (134.67±8.74 vs 245.33±19.14 and 300.33±14.01, P<0.05). The results of Ki-67 protein staining assay showed that compared with the negative control group and blank control group, the expression of Ki-67 protein was significantly decreased in the transfection group (5.93±0.22 vs 8.36±0.09 and 8.70±0.21, P<0.05). The results of AO/PI assay revealed that the ratio of apoptotic cells to living cells in the transfer group was significantly higher than that in the other two groups (0.43±0.07 vs 0.14±0.04 and 0.11±0.04, P<0.05). Conclusion: The proliferation ability of HCT-8 colon cancer cells decreases, and the apoptosis ability increases by decreasing the expression of NRP-2.

LncRNA regulation: New frontiers in epigenetic solutions to drug chemoresistance

Long-noncoding RNAs (lncRNAs) have been shown to participate in sensitizing or de-sensitizing cancer cells to chemical drugs during cancer therapeutics. Notably, a plethora of lncRNAs have been confirmed to be associated with epigenetic controllers and regulate histone protein modification or DNA methylation states in the process of gene transcription. This correlation between lncRNAs and epigenetic regulators can induce the expression of core genes to trigger drug resistance. In addition, epigenetic signatures are considered to be effective and attractive biomarkers for monitoring drug therapeutic effects because they are inheritable, dynamic, and reversible. Therefore, the regulatory mechanism between lncRNAs and epigenetic machinery can serve as a novel indicator and target to overcome or reverse drug resistance in cancer therapy. In this review, we also presented a curated selection of computational tools (including online databases and network analysis) in the area of epigenetics. A classic workflow for lncRNA expression network analysis is presented, providing guidance for non-bioinformaticians to identify significant correlation between lncRNAs and other biomolecules.

Identification of novel monoclonal antibodies targeting the outer membrane protein C and lipopolysaccharides for Escherichia coli O157:H7 detection

AIMS

To identify and evaluate the application of two novel monoclonal antibody (mAb) 2G12 against outer membrane protein (Omp) C and mAb 12B1 targeting the O chain of the lipopolysaccharides (LPS) of Escherichia coli O157:H7 (ECO157).

METHODS AND RESULTS

The sensitivity and specificity of these two antibodies were evaluated with eight ECO157 strains and 68 untargeted strains. mAb 2G12 and 12B1 had no detectable binding with any of the non-O157 strains at 6·0 log₁₀ CFU per ml, while its high specificity and affinity remained with all ECO157 strains. When a higher level (8·0 log₁₀ CFU per ml) was tested, 2G12 and 12B1 did not react with 82·35 and 97·06% of the non-O157 strains respectively. Based on the pair of two antibodies, the sandwich enzyme-linked immunosorbent assay detected 100% (8/8) of ECO157 strains and none of the non-ECO157 strains. The detection limit of ECO157 strains in pure culture were 4·2 ± 0·2 log₁₀ CFU per ml. When the developed test was applied to artificially inoculated beef samples, the detection limit was 6·0 log₁₀ CFU per gram without enrichment and 1·0 log₁₀ CFU per gram after 12 h of enrichment.

CONCLUSIONS

The two novel antibodies identified in this study served as great candidates for the recovery, and detection of ECO157 from different environmental and food samples.

SIGNIFICANCE AND IMPACT OF THE STUDY

ECO157-specific detection was improved by a combination of the novel OmpC mAb and LPS mAb with defined target antigen and good specificity.

Transcranial MR Imaging-Guided Focused Ultrasound Interventions Using Deep Learning Synthesized CT

BACKGROUND AND PURPOSE

Transcranial MR imaging-guided focused ultrasound is a promising novel technique to treat multiple disorders and diseases. Planning for transcranial MR imaging-guided focused ultrasound requires both a CT scan for skull density estimation and treatment-planning simulation and an MR imaging for target identification. It is desirable to simplify the clinical workflow of transcranial MR imaging-guided focused ultrasound treatment planning. The purpose of this study was to examine the feasibility of deep learning techniques to convert MR imaging ultrashort TE images directly to synthetic CT of the skull images for use in transcranial MR imaging-guided focused ultrasound treatment planning.

MATERIALS AND METHODS

The U-Net neural network was trained and tested on data obtained from 41 subjects (mean age, 66.4 ± 11.0 years; 15 women). The derived neural network model was evaluated using a k-fold cross-validation method. Derived acoustic properties were verified by comparing the whole skull-density ratio from deep learning synthesized CT of the skull with the reference CT of the skull. In addition, acoustic and temperature simulations were performed using the deep learning CT to predict the target temperature rise during transcranial MR imaging-guided focused ultrasound.

RESULTS

The derived deep learning model generates synthetic CT of the skull images that are highly comparable with the true CT of the skull images. Their intensities in Hounsfield units have a spatial correlation coefficient of 0.80 ± 0.08, a mean absolute error of 104.57 ± 21.33 HU, and a subject-wise correlation coefficient of 0.91. Furthermore, deep learning CT of the skull is reliable in the skull-density ratio estimation (r = 0.96). A simulation study showed that both the peak target temperatures and temperature distribution from deep learning CT are comparable with those of the reference CT.

CONCLUSIONS

The deep learning method can be used to simplify workflow associated with transcranial MR imaging-guided focused ultrasound.

Metabolic interactions between flumatinib and the CYP3A4 inhibitors erythromycin, cyclosporine, and voriconazole

Flumatinib, indicated for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia, is a structural analog of imatinib and has shown higher potency than imatinib as a BCR-ABL inhibitor. In this paper, the metabolic profile of flumatinib was studied. It was found that CYP3A4 and CYP2C8 were the main cytochrome P450 enzyme substyles catalyzing the metabolism of flumatinib, and CYP3A4 has a stronger metabolic ability for flumatinib than CYP2C8. Erythromycin, cyclosporine, and voriconazole can inhibit the metabolism of flumatinib in vitro. Accordingly, co-administration of erythromycin and cyclosporine with flumatinib increased the plasma concentration and the systemic exposure of flumatinib in rats, which indicated that lower doses should be considered in clinical practice.

Raman Spectroscopy to Characterize Bladder Tissue for Multidimensional Diagnostics of Cancer in Urology

Fiber optic Raman spectroscopy offers labelfree identification of cancer in the bladder under in vivo conditions. However, state-of-the-art Raman technology does not enable to scan the entire bladder wall. Our multidimensional approach within the project Uro-MDD combines panoramic 3D-image reconstruction of white light cystoscopy and fluorescence lifetime imaging to define regions of interest for Raman-assisted diagnostics. First Raman results are presented from human control and cancer bladder specimens that demonstrated how to obtain specific molecular information. Such Raman images can be used in a clinical setting to determine cancer margins and the resection status. Fiber probes are under development to translate the technique to in vivo screening.

Grid refinement in the three-dimensional hybrid recursive regularized lattice Boltzmann method for compressible aerodynamics

Grid refinement techniques are of paramount importance for computational fluid dynamics approaches relying on the use of Cartesian grids. This is especially true of solvers dedicated to aerodynamics, in which the capture of thin shear layers require the use of small cells. In this paper, a three-dimensional grid refinement technique is developed within the framework of hybrid recursive regularized lattice Boltzmann method (HRR-LBM) for compressible high-speed flows, which is an efficient collide-stream-type method on a compact D3Q19 stencil. The proposed method is successfully assessed considering several test cases, namely, an isentropic vortex propagating through transition interface, shock-vortex interaction with intersection between grid refinement interface and shock corrugation, and transonic flows over three-dimensional DLR-M6 wing with seven levels of grid refinement.

Exosome-transmitted lncRNA PCGEM1 promotes invasive and metastasis in gastric cancer by maintaining the stability of SNAI1

PURPOSE

Clinically, hypoxia is associated with increased distant metastasis and poor survival in gastric cancer (GC). In this study, we set out from the cellular interaction to further explain the molecular mechanism of invasion in GC cells under hypoxic conditions.

METHODS

Gastric cancer cells were cultured under 1% O₂ (hypoxia-cultured gastric cancer cells, HGC) and 20% O₂ condition (normoxic-cultured gastric cancer cells, NGC). NGC was co-cultured with HGC-medium. Scrape and Transwell were used to evaluate invasion and migration. Exosomes from GC were extracted by ultracentrifugation. Electron microscopy images, western-blot used to analyze the size distributions and the number of exosomes.

RESULTS

HGC-medium induced NGC dissociated. Long non-coding RNA (lncRNA) prostate cancer gene expression marker 1 (PCGEM1) was specifically expressed in HGC exosomes. HGC-derived PCGEM1-riched exosomes could promote the invasion and migration of NGC. On the mechanism, PCGEM1 maintained stability and reduced the degradation of SNAI1, which could induce the epithelial-mesenchymal transition of GC.

CONCLUSION

LncRNA PCGEM1 was overexpressed in GC cells. And part of the PCGEM1 can be encapsulated into exosomes. These exosomes promoted invasion and migration of other GC cells. We considered PCGEM1 might act as a "scaffold" combined with SNAI1 and prompt the invasion and migration of GC.

[Complexity of Detecting CRISPR/Cas9-Mediated Homologous Recombination in Zebrafish]

Homology-directed (HD) genome modification offers an opportunity to precisely modify the genome. Despite reported successful cases, for many loci, precise genome editing remains challenging and inefficient in vivo. Here we report an effort to precisely knock-in a GFP reporter into gad locus mediated by CRISPR/Cas9 system in the zebrafish Danio rerio. PCR artifact was detected in testing for homologous recombination (HR), but was mitigated by optimizing PCR condition and decreasing the injected targeting plasmid concentration. Under this optimized condition, time course analysis revealed a decline of the HR-positive embryos at embryogenesis progressed. GFP signals also diminished at later developmental stages. The GFP signals were consistent with PCR detection, both of which suggested the loss of targeted insertion events at later stages. Such loss of insertion might be one underlying reason for the inability to obtain germ-line transgenic lines with GFP knocked into the gad locus. Our results suggest that the low HR efficiency associated with CRISPR-mediated knock-in is in part due to loss of insertion after targeted integration into the gad locus.

FBW7 inhibits nucleus pulposus cells proliferation by downregulation of cyclin E in the intervertebral disc degeneration

The article "FBW7 inhibits nucleus pulposus cells proliferation by downregulation of cyclin E in the intervertebral disc degeneration, by J.-W. Xu, J. Wang, K. Yang, S. Guo, C.-S. Feng, H.-Y. Chen, H.-P. Li, published in Eur Rev Med Pharmacol Sci 2020; 24(2):508-516. DOI: 10.26355/eurrev_202001_20026. PMID: 32016952" has been withdrawn from the authors. The Publisher apologizes for any inconvenience this may cause.

Epigenetic Mechanisms Underlying Organic Solute Transporter β Repression in Colorectal Cancer

Colorectal cancer (CRC) is known to be the third most common cancer disease and the fourth-leading cause of cancer-related deaths worldwide. Bile acid, especially deoxycholic acid and lithocholic acid, were revealed to play an important role during carcinogenesis of CRC. In this study, we found organic solute transporter β (OSTβ), an important subunit of a bile acid export transporter OSTα-OSTβ, was noticeably downregulated in CRC. The decline of OSTβ expression in CRC was determined by Western blot and real-time polymerase chain reaction (RT-PCR), whereas chromatin immunoprecipitation (ChIP) was used to evaluate the histone acetylation state at the OSTβ promoter region in vivo and in vitro. CRC cell lines HT29 and HCT15 were treated with trichostation A (TSA) for the subsequent determination, including RT-PCR, small interfering RNA (siRNA) knockdown, ChIP, and dual-luciferase reporter gene assay, to find out which histone acetyltransferases and deacetylases exactly participated in regulation. We demonstrated that after TSA treatment, OSTβ expression increased noticeably because of upregulated H3K27Ac state at OSTβ promoter region. We found that stimulating the expression of p300 with CTB (Cholera Toxin B subunit, an activator of p300) and inhibiting p300 expression with C646 (an inhibitor of p300) or siRNA designed for p300 could control OSTβ expression through modulating H3K27Ac state at OSTβ promoter region. Therefore, downregulated expression of p300 in CRC may cause low expression of OSTβ in CRC via epigenetic regulation. Generally, we revealed a novel epigenetic mechanism underlying OSTβ repression in CRC, hoping this mechanism would help us to understand and inhibit carcinogenesis of CRC. SIGNIFICANCE STATEMENT: Organic solute transporter β (OSTβ) expression is lower in colon cancer tissues compared with adjacent normal tissues. We revealed the epigenetic mechanisms of it and proved that p300 controls OSTβ expression through modulating H3K27Ac state at OSTβ promoter region and hence causes low expression of OSTβ in colorectal cancer.

Non-ambulatory dogs with cervical intervertebral disc herniation: single versus multiple ventral slot decompression

OBJECTIVE

To evaluate the proportion of non-ambulatory dogs with cervical intervertebral disc herniation (IVDH) in a private clinic and to compare signalment and outcome between those that underwent single or multiple ventral slot decompression (VSD).

DESIGN

Retrospective cohort study.

METHODS

After screening 43,378 medical records (January 2010-September 2016), those of 185 dogs with non-ambulatory tetraparesis or tetraplegia along with cervical IVDH that had undergone single (123) or multiple (62) VSD were included in this study. Data on signalment, preoperative neurological status, location of affected intervertebral disc(s), time to ambulation and short-term outcome were compared between single and multiple VSD groups.

RESULTS

The proportion of non-ambulatory dogs with IVDH was 35.3%. The prevalence of non-ambulation was higher in male dogs (0.56%) than in female dogs (0.26%; P < 0.001) and in neutered dogs than in unneutered dogs (0.51% and 0.27%, respectively, P < 0.001). After surgery, 96.2% of the dogs reached ambulatory status. Dogs with multiple IVDH were older than those with single IVDH. Sex, neutering status or size did not affect the outcome or ambulation status postsurgery. The Pekingese was the most commonly affected breed in both groups. There was no difference in the time to reach ambulation and the presence of neurological deficits after surgery between dogs that underwent single and multiple VSD.

CONCLUSIONS

In this cohort, dogs undergoing multiple VSD had a good postoperative outcome, and their short-term functional recovery was equal to that of dogs undergoing single ventral slot compression.

The failure of DAC to induce OCT2 expression and its remission by hemoglobin-based nanocarriers under hypoxia in renal cell carcinoma

Background: Human organic cation transporter 2 (OCT2) is the most abundant and important uptake transporter involved in the renal excretion of cationic drugs. Abnormal hypermethylation- mediated silencing of OCT2 results in oxaliplatin resistance in renal cell carcinoma (RCC). The epigenetic activation of OCT2 by decitabine (DAC) reversed this resistance in normoxic conditions. Given the hypoxic characteristic of RCC, it is still unclear whether hypoxia promotes DAC resistance and is involved in the regulation of OCT2. Methods: The mRNA and protein expression of OCT2 was determined by qRT-PCR and Western blotting. MSRE-qPCR and BSP were used to examine methylation modifications at the OCT2 promoter. The ChIP-qPCR analysis was performed to detect the abundance of histone modification and HIF-1α. The accumulation of DAC and 5-mC were detected using LC-MS, and the amount of 5-hmC was determined by dot blot analysis. To understand the role of hypoxia in the regulation of equilibrative nucleoside transporter 1 (ENT1) expression, the HIF-1α KO cell model was constructed. The re-emulsion method was used for the construction of H-NPs, an oxygen nanocarrier based on hemoglobin, to alleviate the drug resistance of DAC under hypoxia. Results: DAC was unable to upregulate OCT2 expression in hypoxic conditions because of the hypermethylation and low H3K4me3 modification in its promoter region. Hypoxia-mediated repression of human ENT1, which was markedly suppressed in RCC, resulted in a decrease in the cellular accumulation of DAC. Besides, hypoxia-induced upregulation of histone deacetylase HDAC9, which impaired the enrichment of H3K27ac modification in the OCT2 promoter, led to the transcriptional repression of OCT2. H-NPs could attenuate the hypoxia-induced loss of DAC activity and sensitize RCC cells to the sequential combination therapy of DAC and oxaliplatin. Conclusions: Hypoxia-mediated repression of ENT1 led to the inability of DAC to upregulate the expression of OCT2 under hypoxia. H-NPs could alleviate resistance to oxaliplatin and DAC in RCC cells under hypoxia and may have potential clinical applications.

Interactive effects of dietary vitamin K3 and Bacillus subtilis PB6 on the growth performance and tibia quality of broiler chickens with sex separate rearing

Both vitamin K and probiotics can promote the bone health of poultry and mammals. The present study was conducted to investigate the interactive effects between vitamin K3 (VK3) and Bacillus subtilis PB6 on the growth performance and tibia quality of broiler chickens with sex separate rearing. In a 3 × 2 × 2 factorial arrangement, 720 one-day-old broiler chicks (Arbor Acres) were assigned to 12 groups with three levels of dietary VK3 (0, 0.5 and 4.0 mg/kg), with or without probiotic supplementation (500 g/t) and with sex separation (male and female). Each group included 3 replicates with 20 birds per replicate. During day 1 to 21, 0.5 and 4.0 mg/kg of VK3 increased average daily gain (ADG) of all birds and average daily feed intake of male birds (P < 0.05). During day 22 to 42, probiotic supplementation increased the ADG of birds (P < 0.05). Probiotic addition increased the weight, length, diameter and strength of tibia in all birds, and 0.5 and 4.0 mg/kg of VK3 increased the tibial breaking strength of male birds at day 21 (P < 0.05). Vitamin K3 and probiotic synergistically increased tibial breaking strength at day 42 and ash content at day 21 (P < 0.05). Three factors exhibited interactive effects on the chemical composition of tibia at day 42, and female birds fed 4 mg/kg of VK3 and probiotic had the highest contents of ash, calcium and phosphorus (P < 0.05). Bacillus subtilis PB6 increased the serum phosphorus level of male birds at day 21 and serum calcium level of female ones at day 42 (P < 0.05). At day 21, in the probiotic-supplemented birds, serum osteocalcin (OCN) and bone-specific alkaline phosphatase (BALP) were increased by 0 and 4.0 mg/kg of VK3, respectively (P < 0.05). Probiotic increased serum OCN and cooperated with VK3 to increase the serum BALP at day 42 (P < 0.05). Vitamin K3 and probiotic synergistically down-regulated the mRNA expression of Runt-related transcription factor 2 and OCN at day 21 (P < 0.05). Vitamin K3 down-regulated the alkaline phosphatase (liver/bone/kidney) expression in male birds at day 21 and 42, but probiotic up-regulated the expression of these genes at day 42 (P < 0.05). In conclusion, VK3 and B. subtilis PB6 promoted the growth performance of broilers during starter and grower phases, respectively. They synergistically improved the physical and chemical traits of tibias, especially in grower phase, by modulating calcium and phosphorus metabolism as well as osteogenic gene expression.

FBW7 inhibits nucleus pulposus cells proliferation by downregulation of cyclin E in the intervertebral disc degeneration

OBJECTIVE

TF-box and WD repeat domain-containing 7 (FBW7), a component of SCF ubiquitin ligase complex, usually acts as a tumor suppressor because it has an ability in the inhibition of cell proliferation. Nevertheless, the role of FBW7 in intervertebral disc degeneration (IDD) is not quite understood.

MATERIALS AND METHODS

The total protein and RNA were isolated from patients' disc tissues. WB was carried out to analyze the collagen II and FBW7 protein levels of different Pfirrmann grades disc degeneration. Reverse transcription-polymerase chain reaction (RT-PCR) was used to test the collagen II and FBW7 mRNA expression in these disc samples. NP cells were transfected with siRNA-FWB7 to downregulate the FBW7 expression. SiRNA-NC was used as the sham group. Cyclin E, E2F1, and E2F2 were analyzed with WB and RT-PCR.

RESULTS

In this study, different kinds of degenerated disc tissues were analyzed, and it was found that FBW7 was overexpressed in much severe degeneration condition, which was also proved by the IL-1β stimuli nucleus pulposus (NP) cells degeneration model in vitro. Interestingly, the results showed that FBW7 suppression could reverse the degeneration of NP cells. Furthermore, we found that FBW7 induced NP cell cycle arrest in the G1 phase of and inhibited cell proliferation by upregulating p27 expression in vitro. The overexpression of p27 resulted in the inhibition of cyclin E, which promotes cell proliferation.

CONCLUSIONS

Taken together, our study uncovered that FBW7 played an essential inhibitory role in NP cells proliferation, providing new insights that FBW7 may be a potential strategy for IDD treatments.

Isolation and characterization of Streptococcus suis strains from swine in Jiangsu province, China

AIMS

The aim of this study is to investigate Streptococcus suis strains present in Jiangsu province, China.

METHODS AND RESULTS

In all, 1650 nasal and anal swab samples and 100 tonsils were collected from clinically healthy swine. Culture characteristics, colony morphology and PCR-based analysis of the glutamate dehydrogenase (gdh) gene were performed for S. suis identification, and eight isolates were confirmed to be S. suis. The isolates serogroups were identified by agglutinating test, including 4, 7, 3, 5 and 8. Gene profiling by PCR showed that the manN, purD, orf2, gdh genes were conserved among the isolates and that 50% of the isolates carried dltA, pgdA, srtA and sspA. Antimicrobial susceptibility test showed the isolates displayed resistance to clindamycin, erythromycin, tetracycline, penicillin G, vancomycin and linezolid; while none was resistant to chloramphenicol, multi-drug resistance was seen in most of the isolates. Finally, the LD₅₀ (assessed by zebrafish) of isolates RD105 was 2·6431 × 10⁵ and HA24 was 7·1198 × 10⁶ , which showed RD105 more virulent and was consistent with the results of virulence factor identification.

CONCLUSIONS

There is a very low proportion of S. suis in the healthy pigs. The virulence factors were related to pathogenicity. Bacteria in Nantong possess greater virulence potential than those in Huaian.

SIGNIFICANCE AND IMPACT OF THE STUDY

Systematic investigation of S. suis provided the most basic theoretical support for the prevention and control of swine streptococcosis.

Imaging perturbed shock propagation in powders

A novel experimental methodology is presented to study the deviatoric response of powders in shock regimes. The powders are confined to a cylindrical wedge volume, and a projectile-driven shock wave with a sinusoidally varying front propagates through the powder. The perturbed shock wave exhibits a damping behavior due to irreversible processes of viscosity and strength (deviatoric) of the powder with propagation through increasing powder thicknesses. The inclined surface of the wedge is polished and coated to establish a diffuse surface suitable for reflecting incident laser light into a high-speed camera imaging at 5 MHz. Images of the contrast loss upon shock wave arrival at the observation surface are post-processed for qualitative and quantitative information. New data of shock damping behavior with parameters of perturbation wavelength and initial shock strength are presented for powders of copper, tantalum, and tungsten carbide as well as their mixtures. We present the first full-field images showing additional spatial disturbances on the perturbed shock front that appear dependent on particle material and morphology.