Establishment of a neuroblastoma mouse model by subcutaneous xenograft transplantation and its use to study metastatic neuroblastoma

The aim of this study was to establish a metastatic human neuroblastoma (NB) mouse model by xenograft in order to study the metastatic mechanisms of NB. A human NB cell line was obtained from a 5-year-old patient and cultured in vitro. A suspension of these cells was subcutaneously inoculated into nude mice at the right flank next to the forelimb. The biological characteristics of the developed subcutaneous and metastatic tumors were analyzed by hematoxylin and eosin staining. The expression of the tumor marker neuron-specific enolase was determined by immunohistochemistry, and the invasive ability of metastatic tumors was examined by a Matrigel invasion assay. DNA microarray analyses were performed to examine the metastasis-related gene expression. Our results showed that tumors grew in 75% of the mice injected with NB cells and the rate of metastasis was 21%. The xenograft tumors retained the morphological and biological characteristics of the NB specimen from the pediatric patient. Neuron-specific enolase was highly expressed in both subcutaneous and metastatic tumors. The metastatic tumor cells possessed a higher invasive capability than the primary NB cells. The expression of 25 metastasis-related genes was found to be significantly altered in metastatic tumors compared to primary tumors, including RECK, MMP2, VEGF, MMP3, and CXCL12. In conclusion, we successfully established a human NB xenograft model with high tumor-bearing and metastatic rates in nude mice, providing an ideal animal model for the in vivo study of NB.

Genome-wide identification and evolutionary analysis of nucleotide-binding site-encoding resistance genes in Lotus japonicus (Fabaceae)

Nucleotide-binding site (NBS) disease resistance genes play a crucial role in plant defense responses against pathogens and insect pests. Many NBS-encoding genes have been detected in Lotus japonicus, an important forage crop in many parts of the world. However, most NBS genes identified so far in L. japonicus were only partial sequences. We identified 45 full-length NBS-encoding genes in the L. japonicus genome, and analyzed gene duplications, motifs, and the molecular phylogeny to further understand the NBS gene family. We found that gene duplication events rarely occur in L. japonicus NBS-encoding (LjNBS) genes. In addition, LjNBS genes were subjected to selection pressure, and codon usage bias was evident. We tested for purifying selection (specifically in the CC-NBS-LRR and TIR-NBS-LRR groups), and found strong purifying selection in the TIR-domain-containing sequences, indicating that the CC-NBS-LRR group is more likely to undergo expansion than the TIR-NBS-LRR group. Moreover, our results showed that both selection and mutation contributed to LjNBS codon usage bias, but mutational bias was the major influence on codon usage.

Elevated TrkA receptor expression is associated with all-trans retinoic acid-induced neuroblastoma differentiation

Neuroblastoma is the most common and one of the deadliest among pediatric tumors; however, a subset of infants with neuroblastoma display spontaneous regression. The mechanism of spontaneous regression remains to be elucidated. TrkA plays an essential role in the differentiation and functionality of neurons; abundant TrkA expression is associated with favorable prognosis of neuroblastoma. All-trans retinoic acid (ATRA), a first-line drug for acute promyelocytic leukemia (APL) treatment, has been shown to induce differentiation and inhibit cell growth. Neuroblastoma tissues in our hospital inpatient were collected, primary cell culture was performed, and the cells were separated and purified to be cell line. Trypan blue exclusion was used to count the numbers of cells alive, morphological changes were observed under the phase-contrast microscope. RT-PCR was used to determine the expression level of TrkA. In this study, a human neuroblastoma cell line was successfully established; in addition, we demonstrated that ATRA induces growth arrest and promotes the differentiation of neuroblastoma cells. In addition, ATRA was shown to significantly increase the levels of TrkA mRNA expression. Therefore, we concluded that the elevated expression of the TrkA receptor is associated with ATRA-induced growth arrest and differentiation o neuroblastoma cells. The results of this study provide a theoretical basis for the clinical application of differentiation-inducing ATRA for neuroblastoma therapy.

Microphthalmia-associated transcription factor/T-box factor-2 axis acts through Cyclin D1 to regulate melanocyte proliferation

OBJECTIVES

Control of cell proliferation is critical for accurate cell differentiation and tissue formation, during development and regeneration. Here, we have analysed the role of microphthalmia-associated transcription factor MITF and its direct target, T-box factor TBX2, in regulating proliferation of mammalian neural crest-derived melanocytes.

MATERIALS AND METHODS

Immunohistochemistry was used to examine spatial and temporal expression of TBX2 in melanocytes in vivo. RNAi and cell proliferation analysis were used to investigate functional roles of TBX2. Furthermore, quantitative RT-PCR, western blot analysis and flow cytometry were used to further scrutinize molecular mechanisms underlying TBX2-dependent cell proliferation.

RESULTS

TBX2 was found to be co-expressed with MITF in melanocytes of mouse hair follicles. Specific Tbx2 knockdown in primary neural crest cells led to inhibition MITF-positive melanoblast proliferation. Tbx2 knockdown in melan-a cells led to reduction in Cyclin D1 expression and G1-phase cell cycle arrest. TBX2 directly activated Ccnd1 transcription by binding to a specific sequence in the Ccnd1 promoter, and the defect in cell proliferation could be rescued partially by overexpression of Cyclin D1 in Tbx2 knockdown melanocytes.

CONCLUSIONS

Results suggest that the Mitf-Tbx2-Cyclin D1 pathway played an important role in regulation of melanocyte proliferation, and provided novel insights into the complex physiology of melanocytes.

Effects of anticoagulation on markers of activation of clotting following major orthopedic surgery

INTRODUCTION

This study examines makers of activation of clotting following three chemoprophylactic regimens used for prevention of postoperative venous thromboembolic disease (TED) following high-risk surgery for TED.

METHODS

Patients having elective primary knee or hip replacement surgery received variable dose warfarin (target international normalized ratios 2.0-2.5), 1 mg warfarin daily starting 7 days preoperatively or aspirin 325 mg daily starting on the day of surgery. Twelve patients in each group were treated for 28 ± 2 days. Thrombin-antithrombin (T-AT) and prothrombin fragment F1 + 2 were measured at baseline and postoperative days 3 and 28 ± 2.

RESULTS

Thrombin-antithrombin and F1 + 2 on postoperative day 3 were equal for the study groups. By days 28 ± 2, variable dose warfarin therapy group suppressed production of F1 + 2 (P = 0.002) with no difference in the T-AT accumulation. F1 + 2 for other patients overlapped the normal range.

CONCLUSION

The signals of activated clotting following surgery did not differentiate the three regimens on postoperative day 3. Variable dose warfarin was associated with suppression of F1 + 2 after 1 month of therapy, with no effect on accumulation of T-AT. Fixed low-dose warfarin started 7 days prior to surgery and aspirin are not inferior on postoperative day 3, but appear to be inferior over a longer treatment.

Immune memory responses to HBV vaccine 13-18 years after primary vaccination

The aim of this study was to evaluate the immune memory response 13-18 years after an hepatitis B virus (HBV) vaccine by performing a specific in vitro stimulation experiment. Thirty healthy volunteers who had been inoculated 13-18 years ago with the HBV vaccine were collected from the physical examination center. Peripheral blood mononuclear cells were stimulated with 50 ng/mL recombinant HBsAg. An ELISA kit was used for the detection of antibodies that were produced by these cells in vitro. It was found that even 13-18 years after inoculation with the HBV vaccine, an anamnestic antibody response still existed, and was not correlated with the serum antibody levels (r = -0.177, P = 0.377). In conclusion, our data showed that the individuals after inoculation, including those with anti-HBs <10 IU/L as well as those individuals in whom the antibody was not detected, retained immune memory, which may be the main role of memory B cells.

Reproductive factors, exogenous hormone use and risk of hepatocellular carcinoma among US women: results from the Liver Cancer Pooling Project

BACKGROUND

Hepatocellular carcinoma (HCC) occurs less commonly among women than men in almost all regions of the world. The disparity in risk is particularly notable prior to menopause suggesting that hormonal exposures during reproductive life may be protective. Exogenous oestrogenic exposures such as oral contraceptives (OCs), however, have been reported to increase risk, suggesting that estrogens may be hepatocarcinogenic. To examine the effects of reproductive factors and exogenous hormones on risk, we conducted a prospective analysis among a large group of US women.

METHODS

In the Liver Cancer Pooling Project, a consortium of US-based cohort studies, data from 799,500 women in 11 cohorts were pooled and harmonised. Cox proportional hazards regression models were used to generate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of reproductive factors and exogenous hormones with HCC (n=248).

RESULTS

Bilateral oophorectomy was associated with a significantly increased risk of HCC (HR=2.67, 95% CI=1.22-5.85), which did not appear to be related to a shorter duration of exposure to endogenous hormones or to menopausal hormone therapy use. There was no association between OC use and HCC (HR=1.12, 95% CI=0.82-1.55). Nor were there associations with parity, age at first birth, age at natural menopause, or duration of fertility.

CONCLUSIONS

The current study suggests that bilateral oophorectomy increases the risk of HCC but the explanation for the association is unclear. There was no association between OC use and HCC risk. Examination of endogenous hormone levels in relation to HCC may help to clarify the findings of the current study.

[Comparison of the binding activity of Lactococcus lactis peptidoglycan protein anchor with different number of motifs]

OBJECTIVE

The aim of the present study was to compare the binding activity of Lactococcus lactis peptidoglycan protein anchor (PA) with different number of motifs.

METHODS

L. lactis PA gene sequences with 2 and 3 lysin motifs (LysM) were obtained by PCR amplification. Then, the recombinant plasmid of pET-32a(+) containing PA gene was constructed and transformed into E. coli BL21 (DE3) , and induced to express the fusion protein PA2 and PA3. The purified and refolded PA2 and PA3 were incubated with gram positive enhancer matrix (GEM). The binding activities of PA2 and PA3 were identified and compared by Western blot, TEM and SDS-PAGE.

RESULTS

The PA2 and PA3 could bind to GEM. The anchoring activity of PA3 was obviously superior to the PA2.

CONCLUSION

The data indicated that PA with 3 LysMs had a better binding capacity compared with 2 LysMs. The results provided foundations to further improve the design of GEM-PA display system.

RNA-sequencing of the brain transcriptome implicates dysregulation of neuroplasticity, circadian rhythms and GTPase binding in bipolar disorder

RNA-sequencing (RNA-seq) is a powerful technique to investigate the complexity of gene expression in the human brain. We used RNA-seq to survey the brain transcriptome in high-quality postmortem dorsolateral prefrontal cortex from 11 individuals diagnosed with bipolar disorder (BD) and from 11 age- and gender-matched controls. Deep sequencing was performed, with over 350 million reads per specimen. At a false discovery rate of <5%, we detected five differentially expressed (DE) genes and 12 DE transcripts, most of which have not been previously implicated in BD. Among these, Prominin 1/CD133 and ATP-binding cassette-sub-family G-member2 (ABCG2) have important roles in neuroplasticity. We also show for the first time differential expression of long noncoding RNAs (lncRNAs) in BD. DE transcripts include those of serine/arginine-rich splicing factor 5 (SRSF5) and regulatory factor X4 (RFX4), which along with lncRNAs have a role in mammalian circadian rhythms. The DE genes were significantly enriched for several Gene Ontology categories. Of these, genes involved with GTPase binding were also enriched for BD-associated SNPs from previous genome-wide association studies, suggesting that differential expression of these genes is not simply a consequence of BD or its treatment. Many of these findings were replicated by microarray in an independent sample of 60 cases and controls. These results highlight common pathways for inherited and non-inherited influences on disease risk that may constitute good targets for novel therapies.

Association of anthropometric measures and hemostatic factors in postmenopausal women: a longitudinal study

BACKGROUND AND AIMS

Obesity has been associated with increased levels of hemostatic factors. However, few studies have compared change in different anthropometric measures of adiposity in relation to change in levels of hemostatic factors. Our aim was to examine prospectively the association of change in body mass index (BMI), waist-hip ratio (WHR), waist circumference (WC), and waist circumference-height ratio (WHtR) with change in markers of hemostasis in a population of postmenopausal women.

METHODS AND RESULTS

A subsample of women in the Women's Health Initiative (WHI) cohort had fasting blood samples and anthropometric measurements obtained at multiple time points over 12.8 years of follow-up. Of these, we studied the 2593 women who were not in the intervention arm of any WHI clinical trial. Their blood samples were used to measure plasma fibrinogen, factor VII antigen activity, and factor VII concentration at baseline, and at years 1, 3, and 6. We conducted mixed-effects linear regression analyses to examine the longitudinal association between change in anthropometric factors and change in hemostatic factors, adjusting for a wide range of potential confounding factors. In longitudinal analyses using repeated measures, change in BMI, WC, and WHtR were all positively associated with change in all 3 hemostatic factors. Change in anthropometric variables was most strongly associated with change in fibrinogen.

CONCLUSIONS

Our results suggest that an increase in adiposity over time is robustly associated with increased levels of hemostatic factors. Registration number of clinical trial: NCT00000611.

Application of passive sampling in assessing the occurrence and risk of antibiotics and endocrine disrupting chemicals in the Yangtze Estuary, China

Polar organic chemical integrative sampler (POCIS) was used in assessing the occurrence and risk of 12 widely used antibiotics and 5 most potent endocrine disrupting chemicals (EDCs) in the Yangtze Estuary, China. During laboratory validation, the kinetics of pollutant uptake by POCIS were linear, and the sampling rates of most compounds were raised by flow rate and salinity, reaching the highest values at salinity 14‰. The sampling rates varied with the target compounds with the EDCs showing the highest values (overall average=0.123Ld(-1)), followed by chloramphenicols (0.100Ld(-1)), macrolides (0.089Ld(-1)), and finally sulfonamides (0.056Ld(-1)). Validation in the Yangtze Estuary in 2013 showed that the field sampling rates were significantly greater for all compounds except bisphenol A, in comparison to laboratory results, and high-frequency spot sampling is critical for fully validating the passive sampler. The field studies show that antibiotics were widely detected in the Yangtze Estuary, with concentrations varying from below quantification to 1613ngL(-1), suggesting their widespread use and persistence in estuarine waters. The dominating pollutants in July were sulfonamides with a total concentration of 258ngL(-1) and in October were macrolides with a total concentration of 350ngL(-1). The calculation of risk quotient suggested that sulfapyridine, sulfaquinoxaline and erythromycin-H2O may have caused medium damage to sensitive organisms such as fish.

Association between smoking and deaths due to colorectal malignant carcinoma: a national population-based case-control study in China

BACKGROUND

This study explored the association between smoking and colorectal malignant carcinoma (CRC) in the Chinese population at the national level for the first time.

METHODS

In the China Nationwide Retrospective Mortality Survey conducted during 1989-1991, 12,942 CRC cases among 1,136,336 all-cause deaths aged ≥30 years were randomly assigned 25,884 control interviews from 325,255 surviving spouses of all-cause deaths across 103 urban and rural areas.

RESULTS

Compared with non-smokers, smoking significantly increased the risk of CRC-specific mortality by 9.8% (odds ratio (OR)=1.098, 95% confidence interval (CI)=1.046-1.153) adjusted for sex, age, and residence. There were significant dose-response relationships between smoking and CRC, such as smoking years, cigarettes smoked daily, and age at onset of smoking. Long-term heavy smokers aged ≥50 years with ≥30 smoking years and ≥20 cigarettes daily had an excess risk of CRC deaths of 30.2% (OR=1.302, 95% CI=1.214-1.397). The strongest association between these smoking variables, such as long-term heavy smokers (OR=1.604, 95% CI=1.341-1.919), and CRC was observed among rural men.

CONCLUSIONS

Quitting smoking at any time would likely be beneficial to CRC prevention. Long-term heavy smokers and rural men should be viewed as special targets for smoking prevention and cessation programs.

Pre-natal undernutrition and post-natal overnutrition are associated with permanent changes in hepatic metabolism markers and fatty acid composition in sheep

AIM

Determine the impacts of pre- and early-post-natal nutrition on selected markers of hepatic glucose and fat metabolism.

METHODS

Twin-bearing ewes were fed 100% (NORM) or 50% (LOW) of protein and energy requirements during the last 6-weeks of gestation. Twin-lambs received either a high-carbohydrate high-fat (HCHF) or conventional (CONV) diet from 3 days to 6 months of age (around puberty), whereafter lambs from the four subgroups were slaughtered (16 males/3 females). Remaining lambs (19 females) were fed a moderate diet and slaughtered at 2 years of age (young adults).

RESULTS

Pre-natal LOW nutrition was associated with increased hepatic triglyceride, ceramide and free fatty acid content in adulthood (not observed in lambs), which was accompanied by up-regulated early-stage insulin signalling as reflected by increased INSRβ and PI3K-p110 protein expression. The HCHF diet increased hepatic triglyceride content in lambs, associated with down-regulated expressions of energy-metabolism-related genes (GLUT1, PPARα, SREBP1c, PEPCK). These post-natal effects were not observed in adult HCHF sheep, after they had received a moderate (body-fat correcting) diet for 1.5 years. Interestingly, pre-natal LOW nutrition induced permanent alterations in hepatic phospholipids' fatty acid composition. Thus, the amount of linoleic acid (C18 : 2 ∆(9,12)) was significantly increased and composition of rumen-derived fatty acids were altered, indicating changed composition of rumenal microbiota.

CONCLUSION

Hepatic insulin signalling and linoleic and microbial-derived fatty acid content in phospholipids are targets of foetal programming induced by late-gestation undernutrition. Future studies are required to explain their cause-effect associations with increased risks of developing hepatic steatosis and insulin insensitivity in adulthood.

CCL17 Induces Trophoblast Migration and Invasion by Regulating Matrix Metalloproteinase and Integrin Expression in Human First-Trimester Placenta

Chemokines and chemokine receptors have been implicated a pivotal role in trophoblast differentiation and in the formation of a functionally normal placenta. In this study, we present data that highlight the involvement of chemokine ligand 17/chemokine receptor 4 (CCL17/CCR4) expression at the fetomaternal interface and expand its biological relevance of influence during trophoblast differentiation and placentation. By immunohistochemistry, we found that CCL17 was abundantly expressed in the decidua and trophoblasts, especially in cell columns. The receptor for CCL17, CCR4, was specifically expressed in invading interstitial extravillous trophoblasts. Furthermore, by transwell migration, invasion assays, and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, we found that exogenous CCL17 concentrations paralleled the invasive potential of cytotrophoblasts to some extent, with no significant effect on cell proliferation. Using Western blotting, we demonstrated that the stimulatory effect of CCL17 was related to the expression of matrix metalloproteinase 2 (MMP-2), MMP-13, integrin α5, and integrin β1, although it downregulated tissue inhibitors of MMP-1 expression. In conclusion, our findings suggest that CCL17, as a differentiation-related molecule coexpressed by decidua and trophoblast, stimulates extravillous trophoblast migration and directs invasion mainly via modulating integrins, MMPs, and its inhibitor levels.

Post-marketing surveillance study with iodixanol in 20 185 Chinese patients from routine clinical practices

Objective:

To determine the incidence of immediate and delayed adverse drug reactions (ADRs), and to assess patient discomfort following administration of iodixanol during imaging examinations in routine clinical practice.

Methods:

A total of 20 185 patients across 95 clinical centres were enrolled in a prospective post-marketing surveillance registry with iodixanol. Patients were monitored for occurrence of ADRs immediately following iodixanol administration and for up to 7 days after administration.

Results:

The overall rate of ADRs was 1.52%, of which 0.58% was immediate and 0.97% was delayed onset. Two patients had non-fatal serious ADRs (0.01%). The ADRs were significantly more common in patients who underwent contrast-enhanced CT/coronary CT angiography vs others (p < 0.001), in those receiving pre-heated iodixanol vs non-heating (p < 0.001), in those aged 70 years or younger (p < 0.001), in those in whom a power injector was used for contrast delivery (p < 0.001) and in those with a history of an allergic reaction to contrast (p = 0.024). Multivariate analysis showed that female gender, intravenous route of contrast injection, body weight ≥80 kg, age less than 65 years, contrast flow rate ≥4 ml s⁻¹ and prior reaction to iodinated contrast medium were all significant and independent contributors to ADRs. Pre-treatment contrast volume and history of cardiac disease, gout, hypertension, diabetes mellitus or asthma did not affect the rate of ADRs. Discomfort was generally mild, with 94.8% of patients reporting a composite score of 0–3.

Conclusion:

The safety of iodixanol in routine clinical practice was shown to be similar to the published safety profiles of other non-ionic iodinated contrast agents. Patient discomfort during administration was mild or absent in most patients.

Advances in knowledge:

The major strength of this study is that it included 20 185 patients enrolled in various types of imaging examinations. The safety profile of iodixanol was comparable to previously published work.

Pro-inflammatory cytokine-mediated ferroportin down-regulation contributes to the nigral iron accumulation in lipopolysaccharide-induced Parkinsonian models

Pro-inflammatory cytokines induced by inflammation and iron accumulation in the substantia nigra (SN) have been implicated in the pathogenesis of Parkinson's disease (PD). In the present study, we aimed to investigate the relationship between inflammation and iron accumulation in a lipopolysaccharide (LPS)-induced Parkinsonian rat model. The activation of glial cells and elevated levels of pro-inflammatory cytokines were observed in the SN of LPS models, accompanied by iron deposits in the same region. Moreover, ferroportin (Fpn), the only channel for iron export, was down-regulated. SH-SY5Y dopaminergic cells were pre-incubated with conditioned media enriched in pro-inflammatory cytokines, and abnormal iron deposits and a drop of Fpn were observed. The expression of heme oxygenase-1 (HO-1) was also upregulated in vivo and in vitro. These results suggested that pro-inflammatory cytokines might induce Fpn downregulation, which leads to iron accumulation and dopaminergic neurons' degeneration in PD. HO-1 may also contribute to the iron accumulation in neurons, but its mechanism needs to be further investigated.

QoI Resistance in Fusicladium carpophilum Populations from Almond in California and Evaluation of Molecular Resistance Mechanisms

Disease management failures have been reported in California for almond scab caused by Fusicladium carpophilum following quinone outside inhibitor (QoI) applications. Resistance in the pathogen populations was found to be common and at high incidence in the major almond-growing regions beginning in 2003, 4 years after registration of azoxystrobin on this crop. Two levels of azoxystrobin resistance, moderate and high, were identified with 50% effective concentration (EC₅₀) values between 0.15 and 10 μg/ml or >40 μg/ml, respectively. Reference isolates collected before resistance was detected had EC₅₀ values <0.05 μg/ml. High-resistance was associated with a G143A mutation in the mitochondrial cytochrome b gene. For the less commonly found moderately resistant isolates, no mutations in the gene were detected between codons 122 and 212. Using primers targeting the G143A mutation or the cytochrome b gene of all F. carpophilum isolates in quantitative polymerase chain reaction (qPCR) analyses, the frequency of highly resistant isolates was accurately determined in mixtures of conidia with selected ratios of sensitive and resistant isolates. The frequency of high resistance in bulked samples of scab lesions, however, was generally underestimated compared with in vitro testing of fungicide sensitivity of fungal isolates from the same lesions. Competition experiments using conidial suspensions demonstrated stability of the highly resistant genotype in the presence of different amounts of sensitive and moderately resistant genotypes. Analysis of covariance of linear regressions of cycle threshold values on DNA concentrations derived from qPCR amplifications using two primer pairs for cytochrome b alleles with and without the G143 mutation showed that several isolates differed in their slopes and midpoints. Thus, heteroplasmy of mitochondrial-inherited QoI resistance is suggested as a likely cause for incongruence in estimating resistance frequencies using the two methods.

The chemokine CXCL6 restricts human trophoblast cell migration and invasion by suppressing MMP-2 activity in the first trimester

STUDY QUESTION

Can the chemokine CXCL6 affect trophoblast cell migration and invasion in human first-trimester placenta?

SUMMARY ANSWER

Chemokine CXCL6 inhibits trophoblast cell migration and invasion by suppressing matrix metalloproteinase (MMP)-2 activity in human first-trimester placenta.

WHAT IS KNOWN ALREADY

Several chemokines including CXCL8, CXCL12, CXCL14, CXCL16, CX3CL1, CCL14 and CCL4 can promote or inhibit trophoblast cell migration and invasion in human first-trimester placenta.

STUDY DESIGN, SIZE, DURATION

We used the trophoblast cell line HTR8/SVneo cells, primary trophoblast cells and villi explants to investigate the effect of rhCXCL6 on trophoblast cell migration and invasion.

PARTICIPANTS/MATERIALS, SETTING, METHODS

First, the CXCL6 RNA transcript level was detected in HTR8/SVneo cells derived from human first-trimester, second-trimester and third-trimester placenta by RT-PCR. Protein expression of CXCL6 and its receptors was tested in first-trimester placenta by immunohistochemistry. Secreted CXCL6 protein was detected in HTR8/SVneo cell supernatants by enzyme-linked immunosorbent assay. Secondly, the effect of rhCXCL6 on HTR8/SVneo cell proliferation was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Thirdly, the effect of rhCXCL6 on cell migration and invasion of HTR8/SVneo cells, primary trophoblast cells and villi explants was tested by transwell migration and invasion assays, respectively. Last, MMP-2 and MMP-9 activity in the supernatants of HTR8/SVneo and primary trophoblast cells treated by rhCXCL6 in the invasion assay was assessed by gelatin zymography.

MAIN RESULTS AND THE ROLE OF CHANCE

Abundance of the CXCL6 RNA transcript increased with pregnancy development. CXCL6 and its receptor were expressed in several cells at the human maternal-fetal interface. RhCXCL6 inhibited trophoblast cell migration and invasion by suppressing MMP-2 activity.

LIMITATIONS, REASONS FOR CAUTION

These experiments are only in vitro.

WIDER IMPLICATIONS OF THE FINDINGS

According to the literature, CXCL6 could promote tumour cell migration and invasion by accelerating MMP-9 activity. However, CXCL6 inhibited trophoblast cell migration and invasion by suppressing MMP-2 activity in human first-trimester interface. These data suggest that strict regulation of CXCL6 is required for normal migration and invasion of cells, such as those involved at the maternal-fetal interface.

High-voltage nanosecond pulses in a low-pressure radio-frequency discharge

An influence of a high-voltage (3-17 kV) 20 ns pulse on a weakly-ionized low-pressure (0.1-10 Pa) capacitively coupled radiofrequency (RF) argon plasma is studied experimentally. The plasma evolution after pulse exhibits two characteristic regimes: a bright flash, occurring within 100 ns after the pulse (when the discharge emission increases by 2-3 orders of magnitude over the steady-state level), and a dark phase, lasting a few hundreds μs (when the intensity of the discharge emission drops significantly below the steady-state level). The electron density increases during the flash and remains very large at the dark phase. 1D3V particle-in-cell simulations qualitatively reproduce both regimes and allow for detailed analysis of the underlying mechanisms. It is found that the high-voltage nanosecond pulse is capable of removing a significant fraction of plasma electrons out of the discharge gap, and that the flash is the result of the excitation of gas atoms, triggered by residual electrons accelerated in the electric field of immobile bulk ions. The secondary emission from the electrodes due to vacuum UV radiation plays an important role at this stage. High-density plasma generated during the flash provides efficient screening of the RF field (which sustains the steady-state plasma). This leads to the electron cooling and, hence, onset of the dark phase.