Electrochemical potential enables dormant spores to integrate environmental signals

The dormant state of bacterial spores is generally thought to be devoid of biological activity. We show that despite continued dormancy, spores can integrate environmental signals over time through a preexisting electrochemical potential. Specifically, we studied thousands of individual Bacillus subtilis spores that remain dormant when exposed to transient nutrient pulses. Guided by a mathematical model of bacterial electrophysiology, we modulated the decision to exit dormancy by genetically and chemically targeting potassium ion flux. We confirmed that short nutrient pulses result in step-like changes in the electrochemical potential of persistent spores. During dormancy, spores thus gradually release their stored electrochemical potential to integrate extracellular information over time. These findings reveal a decision-making mechanism that operates in physiologically inactive cells.

Vessel-Selective 4D-MRA Using Superselective Pseudocontinuous Arterial Spin-Labeling with Keyhole and View-Sharing for Visualizing Intracranial Dural AVFs

BACKGROUND AND PURPOSE

An accurate assessment of the hemodynamics of an intracranial dural AVF is necessary for treatment planning. We aimed to investigate the utility of 4D-MRA based on superselective pseudocontinuous arterial spin-labeling with CENTRA-keyhole and view-sharing (4D-S-PACK) for the vessel-selective visualization of intracranial dural AVFs.

MATERIALS AND METHODS

We retrospectively analyzed the images of 21 patients (12 men and 9 women; mean age, 62.2 [SD,19.2] years) with intracranial dural AVFs, each of whom was imaged with DSA, 4D-S-PACK, and nonselective 4D-MRA based on pseudocontinuous arterial spin-labeling combined with CENTRA-keyhole and view-sharing (4D-PACK). The shunt location, venous drainage patterns, feeding artery identification, and Borden classification were evaluated by 2 observers using both MRA methods on separate occasions. Vessel selectivity was evaluated on 4D-S-PACK.

RESULTS

Shunt locations were correctly evaluated in all 21 patients by both observers on both MRA methods. With 4D-S-PACK, observers 1 and 2 detected 76 (80.0%, P < .001) and 73 (76.8%, P < .001) feeding arteries of the 95 feeding arteries identified on DSA but only 39 (41.1%) and 46 (48.4%) feeding arteries with nonselective 4D-PACK, respectively. Both observers correctly identified 10 of the 11 patients with cortical venous reflux confirmed by DSA with both 4D-S-PACK and 4D-PACK (sensitivity = 90.9%, specificity = 90.9% for each method), and they made accurate Borden classifications in 20 of the 21 patients (95.2%) on both MRA methods. Of the 84 vessel territories examined, vessel selectivity was graded 3 or 4 in 73 (91.2%) and 66 (88.0%) territories by observers 1 and 2, respectively.

CONCLUSIONS

4D-S-PACK is useful for the identification of feeding arteries and accurate classifications of intracranial dural AVFs and can be a useful noninvasive clinical tool.

29 The effect of vitrification at the immature stage on DNA methylation in porcine oocytes and its relevance to subsequent embryo development

Oocyte vitrification is an important approach for invitro gene banking of female germplasm; however, in pigs, it hampers embryo development. In cattle, vitrification at the MII stage was reported to alter epigenetic status in oocytes and even in subsequently developing embryos (Chen et al. 2016 Theriogenology 86, 868-878). The present study investigated the effect of vitrification at the immature stage of porcine oocytes on DNA methylation status and its relevance to subsequent embryo development. Immature cumulus–oocyte complexes were vitrified in microdrops and warmed (vitrified group) or treated with cryoprotectant agents (17.5% ethylene glycol + 17.5% propylene glycol, CPA group) by our method (Appeltant et al. 2018 Cryobiology 85, 87-94). Then they were subjected to IVM, parthenogenetic activation (PA), and embryo culture. From each batch, a group of oocytes was processed without treatment (control group). Oocyte survival and polar body extrusion were recorded after IVM. Cleavage and blastocyst developmental rates were recorded on Day 2 and 6 of culture, respectively (Day 0=PA). In each replication, DNA methylation was assayed in representative oocytes at the MII stage after IVM and in embryos at the 2- to 4-cell stage on Day 2 by immunostaining with 5-methylcytosine (5mC). Relative fluorescent intensity of 5mC in the chromatin was compared among groups. The experiment was replicated 3 times. Data were analysed by ANOVA. After IVM, there was no significant difference among the control, CPA, and vitrified groups in terms of the percentage of live oocytes (99.3, 96.4, and 94.0%, respectively) or polar body extrusion (88.6, 86.9, and 79.6%, respectively). After PA of oocytes with a polar body, there was no difference between the control and CPA groups in the percentage of cleavage (84.1 and 80.7%, respectively) or blastocyst development of cleaved embryos (63.3 and 79.3%, respectively). However, in the vitrified group, cleavage and blastocyst development rates (46.6 and 33.5%, respectively) were reduced (P&lt;0.05) compared with the other groups. The 5mC fluorescence in the DNA of oocytes at the MII stage in the CPA and vitrified groups were similar and significantly lower than that in the control group (0.88±0.02, 0.87±0.001, and 1.0±0.02, respectively) but higher than that in the negative control processed without primary antibody (0.33±0.02). In the embryos at the 2- to 4-cell stage, 5mC fluorescence was not significantly different among the control, CPA, and vitrified groups (1.0±0.1, 0.99±0.1, and 0.96±0.1, respectively) but was significantly higher than that of the negative control (0.36±0.04). In conclusion, CPA treatment reduced DNA methylation levels in oocytes. However, it was restored during early embryo development and did not affect blastocyst development. The results suggest that reduced DNA methylation in vitrified oocytes is caused by CPA but it may not be responsible for their reduced ability to develop to blastocysts.

30 The importance of cumulus cells for the survival and timing of meiotic resumption of porcine oocytes vitrified at the immature stage

Previous research revealed that vitrification at the immature (the germinal vesicle, GV) stage triggers premature meiotic resumption in cumulus-enclosed porcine oocytes and causes a damage in gap junctions (Appeltant et al. 2017 Reprod. Fertil. Dev. 29, 2419-2429). However, the correlation between the two phenomena was not investigated yet. The present research was conducted to clarify whether premature meiotic resumption is caused by gap junction disruption and to assess the importance of cumulus cells for the survival of porcine oocytes vitrified at the GV stage. Cumulus–oocyte complexes (COCs) were collected from 3- to 6-mm antral follicles of slaughtered gilts. Immediately after collection, approximately half of them were denuded mechanically (DOs). In each replicate, groups of COCs and DOs were processed without vitrification (control groups). Treatment groups of COCs and DOs were vitrified on Cryotop sheets in a combination of 17.5% propylene glycol and 17.5% ethylene glycol and warmed in 0.4M sucrose. The oocytes were then cultured for 22h in a chemically defined porcine oocyte medium (POM) supplemented with 10ngmL−1 epidermal growth factor, 10IUmL−1 equine chorionic gonadotrophin, 10IUmL−1 human chorionic gonadotrophin, and 1mM dibutyryl cAMP. After culture, COCs were denuded and oocyte survival was assessed by morphological evaluation of membrane integrity under a stereo microscope. Then, live oocytes were fixed and stained with 1% orcein and nuclear status was evaluated under a phase-contrast microscope. The experiment was replicated 5 times. Data were analysed by ANOVA followed by Tukey’s multiple comparisons test. After vitrification and culture, the survival rate in the COC group was higher (P&lt;0.05) than that of the DO group (160/191=84.7±3.4% vs. 153/237=65.0±6.2%, respectively) but reduced (P&lt;0.05) compared with those in the control COC and DO groups (138/143=96.6±1.0% and 152/153=99.3±0.6%, respectively). The majority of the control COCs and DOs were at the GV stage with similar percentages (95.6±2.2% and 94.0±2.2%, respectively). In contrast, the percentages of oocytes at the GV stage in the vitrified COC and DO groups were reduced (71.6±9.4% and 45.7±10.5%, respectively; P&lt;0.05) compared with the control groups, which were associated with increased frequencies of diakinesis and MI stages. Percentages of oocytes at the GV stage in the vitrified COC and DO groups were not significantly different (P=0.23). In conclusion, cumulus cells can prevent vitrification-related membrane damage of oocytes. Furthermore, vitrification induced premature meiosis both in the cumulus-enclosed and denuded oocytes even in the presence of the meiotic inhibitor, dibutyryl cAMP. Nevertheless, cumulus removal without vitrification did not induce premature meiosis in the oocytes. Therefore, disruption in communication with cumulus cells might not be the primary reason for premature meiosis in vitrified oocytes.

AB0089 THE ANALYSIS FOR THE INHIBITION OF ANGIOGENESIS BY JAK INHIBITOR

Background:

Many blood vessels are generated in the hyperplastic synovial tissue of patients with rheumatoid arthritis (RA), and lead to chronic tissue inflammation and joint destruction [1]. Janus kinase (JAK) family consisting of JAK1, JAK2, JAK3 and tyrosine kinase 2 (TYK2) are chain receptors which phosphorylate signal transducers and activators of transcription (STAT) and mediate inflammatory diseases including RA [2]. Nowadays, several JAK inhibitors such as Tofacitinib (TOF), Baricitinib (BAR) and Peficitinib (PEF) have been developed and demonstrated to have the inhibitory effects on inflammatory arthritis [3-5]. However, there were few reports concerning their effects on angiogenesis in vitro.

Objectives:

The purpose of the present study is to investigate the influence of JAK inhibitors on angiogenesis of human umbilical vein endothelial cell (HUVEC) activated by vascular endothelial growth factor (VEGF).

Methods:

The cell line of HUVECs were used for this study. The activity of proliferation and tube formation were analyzed by counting assay and tube formation assay, respectively.

In counting assay, HUVECs (5 × 104cells/ml) were seeded onto 96-well cell culture plate with 20 ng/ml VEGF including various doses (0.1µM, 1µM, 5µM) of TOF, BAR or PEF. After 48 hours incubation at 37°C in a humidified atmosphere containing 5% CO2, cell proliferation of each groups was assessed using cell counting kit. In tube formation assay, HUVECs (5 × 104cells/ml) were treated with 20ng/ml VEGF including various dose (0.1µM, 1µM, 5µM) of TOF, BAR or PEF for 00 hours, then seeded onto 48-well plate applied with Matrigel. After 24 hours incubation on Matrigel, the capillary-like tube formation of each well was photographed using phase contrast microscopy. Tube formation were quantitated by measurement of the length of branch.

Results:

HUVECs were activated in proliferation and tube formation by VEGF treatment. And, the proliferation and tube formation of HUVECs activated by VEGF were suppressed by All of TOF, BAR and PEF. In particular, TOF and PEF could suppress them highly.

Conclusion:

This study showed the inhibitory effect of JAK inhibitors on proliferation and tube formation of HUVECs activated by VEGF. In particular, the angiogenesis of HUVECs activated by VEGF was highly suppressed by TOF and PEF. VEGF is reported to regulate the angiogenesis through multi JAK-STAT signaling pathways [6]. The inhibitory effects on angiogenesis of TOF, BAR and PEF might depend on the differences in their affinity for JAKs. VEGF has been shown to a have a central involvement in the angiogenic process in RA [7]. JAK inhibitors might suppress the angiogenesis in RA synovial tissues by inhibiting VEGF signaling.

References:

[1]Scott DL, et al. Rheumatoid arthritis. Lancet. 2010.

[2]Banerjee S, et al. JAK-STAT signaling as a target for inflammatory and autoimmune diseases: current and future prospects. Drugs. 2017.

[3]William D, et al. JAK inhibitors in dermatology: the promise of a new drug class. Journal of the American Academy of Dermatology. 2017.

[4]Dhillon S. Tofacitinib: A Review in Rheumatoid Arthritis. Drugs. 2017.

[5]Markham A, et al. Peficitinib: First Global Approval. Drugs. 2019.

[6]Zhang HY, et al. Three important components in the regeneration of the cavernous nerve: brain-derived neurotrophic factor, vascular endothelial growth factor and the JAK/STAT signaling pathway. Asian journal of andrology. 2011.

[7]Paleolog EM. Angiogenesis in rheumatoid arthritis. Arthritis research. 2002.

Acknowledgments:

none

Disclosure of Interests:

None declared

SAT0019 HISTOPATHOLOGICAL CHANGES OF SYNOVIAL TISSUE IN RHEUMATOID ARTHRITIS PATIENTS TREATED WITH TNF INHIBITORS

Background:

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by hyperplasia of synovial tissues [1]. Tumor necrosis factor (TNF)-α is one of the pro-inflammatory cytokines that play a crucial role in the pathogenesis of RA synovitis, and TNF inhibitors (TNFi) were reported to force the RA to go into remission or low disease activity and have brought revolutionary impacts on RA treatment [2]. TNFi have been shown to act on inflammatory cells and form the discoid fibrosis in the sublining layers [3,4]. However, the changes of synovial tissue and the cause of discoid fibrosis in RA patients treated with TNFi has not been determined in detail.

Objectives:

The purpose of this study is to demonstrate the histological changes and the types of cells around discoid fibrosis in RA synovium treated with TNFi.

Methods:

Synovial tissues were obtained from 30 patients with RA during joint surgeries. 6 patients were treated with TNFi (1 patient with golimumab, 3 patients with etanercept, 2 patients with infliximab). As a control, synovial tissues were obtained from 6 patients who were treated only with csDMARDs (6 patients with MTX). The frozen sections were stained by hematoxylin and eosin (HE). To detect the apoptosis, TdT-mediated dUTP nick end labeling (TUNEL) was performed. The immunohistochemical characterization of the synovial cells was performed by using following antibodies: CD20 and CD3 for detecting B and T lymphocytes respectively, CD163 and CD86 for detecting M1 and M2 macrophage respectively.

Results:

In the sections stained with HE, the formation of discoid fibrosis and the other characteristic changes including hydropic degeneration, vacuolation, sclerosis of small vasculature, and the number of multilayered synovial cells was decreased in synovium from RA patients treated with TNFi. In the sections with TUNEL stain, apoptosis of lining cells around the discoid fibrosis was detected in RA synovium treated with TNFi (Figure 1a, 1b). In the sections with immunohistochemistry stain, CD86 expression increased in lining layer of RA synovium treated with TNFi. CD163 positive cells showed diffuse expression in RA synovium treated with TNFi. In contrast, CD20 and CD3 positive cells decreased around discoid fibrosis compared to control sections. These results showed indicated that the types of cells in lining and sublining layers were mainly macrophages and that the apoptosis of macrophages might form the discoid fibrosis in lining layers.

Conclusion:

This study showed the apoptosis of lining cells derived from macrophages resulted in the formation of the discoid fibrosis. These findings indicated TNFi might induce apoptosis of macrophage leading to the suppression of RA synovitis.

References:

[1] Scott Dl, et al. Progression of radiological changes in rheumatoid arthritis. Ann Rheum Dis. 1984.

[2]van der Heijde D,et al. Comparison of etanercept and methotrexate, alone and combined, in the treatment of rheumatoid arthritis: two-year clinical and radiographic results from the TEMPO study, a double-blind, randomized trial. Arthritis Rheum. 2006.

[3] Hirohata S,et al. TNF inhibitors induce discoid fibrosis in the sublining layers of the synovium with degeneration of synoviocytes in rheumatoid arthritis. Rheumatol Int. 2013.

[4] Yamanaka H,et al. Scoring evaluation for histopathological features of synovium in patients with rheumatoid arthritis during anti-tumor necrosis factor therapy. Rheumatol Int. 2010.

Acknowledgments :

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Disclosure of Interests:

None declared

Early and noninvasive diagnosis using serological antigen biomarkers in chronic invasive fungal rhinosinusitis

Background: Chronic invasive form of fungal rhinosinusitis (FRS) is characterized by the invasion of fungal organisms into the sinonasal mucosa in the background of diabetes mellitus and corticosteroid treatment. Although the histopathology has traditionally been used to make a proven diagnosis of invasive fungal infections, the dependence on tissue samples and the slow turnaround time hamper the early confirmation of such infections. Methodology: This is a retrospective case series conducted over 6 years. All patients with a chronic course and immunosuppressive background of FRS diagnosed by radiologic imaging and treated with endoscopic sinus surgery were eligible for inclusion. Data were collected through medical records, including basic characteristics, symptoms and signs, imaging findings, laboratory investigations, pathology, treatment, and outcomes. Results: Fifteen patients with chronic course and immunosuppressive background of FRS diagnosed by radiologic imaging were identified. High values of 1,3-b-D-glucan (BDG) assay were recognized in 5 patients, whereas the other 10 patients with negative findings in the BDG assay showed sinus mycetomas. All the 5 patients showing significant elevations of serum BDG showed positive findings in the polymerase chain reaction (PCR), but only 2 patients were positive in the histopathology. The findings of the BDG assay were consistent with those of the PCR method, which was superior in sensitivity to the histopathology. Conclusion: We first applied BDG assay as a diagnostic tool for chronic invasive FRS. The BDG assay may be useful to distinguish chronic invasive FRS, including its early stage, from noninvasive mycetoma, contributing to timely treatment.

27 Vitrification at the germinal vesicle stage does not trigger apoptosis in porcine oocytes and early embryos

Porcine immature oocytes can survive vitrification at high rates and retain their ability to undergo maturation and fertilization; however, the procedure reduces their competence for subsequent embryo development via unknown mechanisms (Somfai et al. 2014 Plos One 9, e97731). The aim of the present study was to clarify whether our vitrification procedure at the germinal vesicle stage triggers apoptosis in oocytes and subsequent developing embryos. Immature porcine cumulus-oocyte complexes obtained from slaughterhouse-derived ovaries were vitrified and warmed by our method (Appeltant et al. 2018 Cryobiology 85, 87-94) immediately after collection (vitrified group). The oocytes were equilibrated in 2% (vol/vol) ethylene glycol and 2% (vol/vol) propylene glycol for 13-15min. Then, they were vitrified by dropping them into liquid nitrogen in 2-μL microdrops of a medium composed of 17.5% ethylene glycol, 17.5% propylene glycol, 0.3M sucrose, and 50mgmL−1 polyvinylpyrrolidone. After warming, they were subjected to IVM, fertilization (IVF), and embryo culture using chemically defined media (Yoshioka et al. 2008 J. Reprod. Dev. 54, 208-213). From each collected batch, a group of oocytes was processed without vitrification (control group). Apoptosis was assayed in membrane-intact oocytes at the end of IVM and in cleavage-stage embryos on Day 2 after IVF (Day 0) by the CaspACE FITC-VAD-FMK In Situ Caspase Marker (Promega; Experiment 1), deoxynucleotidyl transferase (TdT) dUTP nick-end labelling (TUNEL; Experiment 2), and analysis of mRNA levels by RT-qPCR for the pro-apoptotic Bax and CASP3 genes (Experiment 3). Each experiment was replicated three times. Data were analysed by Kruskal-Wallis test followed by Dunn's multiple comparisons test. The mean survival rate of vitrified oocytes was 89.2%. There was no significant difference between the control and vitrified groups in relative caspase levels in IVM oocytes and in 2- to 4-cell embryos after IVF; however, significantly increased caspase activity (P&lt;0.05) was detected in oocytes and embryos after treatment with 10 μM staurosporine (positive control). There was no significant difference between the control and vitrified groups in the proportion of TUNEL-positive oocytes (4.1 and 0.8%, respectively) and embryos (0 and 0%, respectively), whereas 96.6% of oocytes and 100% of cleavage stage embryos treated with 1000IUmL−1 deoxyribonuclease I (positive control) were proven to be TUNEL positive (P&lt;0.05). Similar mRNA levels for Bax and CASP3 genes were detected in oocytes at the end of IVM and subsequent developing 4- to 8-cell embryos between the control and vitrified groups. In conclusion, vitrification of porcine oocytes at the germinal vesicle stage by our method did not trigger apoptosis in oocytes and subsequent developing embryos. This work was supported by the Japan Science and Technology Agency (JST)/Japan International Cooperation Agency (JICA) Science and Technology Research Partnership for Sustainable Development (SATREPS).

Statistics of correlated percolation in a bacterial community

Signal propagation over long distances is a ubiquitous feature of multicellular communities, but cell-to-cell variability can cause propagation to be highly heterogeneous. Simple models of signal propagation in heterogenous media, such as percolation theory, can potentially provide a quantitative understanding of these processes, but it is unclear whether these simple models properly capture the complexities of multicellular systems. We recently discovered that in biofilms of the bacterium Bacillus subtilis, the propagation of an electrical signal is statistically consistent with percolation theory, and yet it is reasonable to suspect that key features of this system go beyond the simple assumptions of basic percolation theory. Indeed, we find here that the probability for a cell to signal is not independent from other cells as assumed in percolation theory, but instead is correlated with its nearby neighbors. We develop a mechanistic model, in which correlated signaling emerges from cell division, phenotypic inheritance, and cell displacement, that reproduces the experimentally observed correlations. We find that the correlations do not significantly affect the spatial statistics, which we rationalize using a renormalization argument. Moreover, the fraction of signaling cells is not constant in space, as assumed in percolation theory, but instead varies within and across biofilms. We find that this feature lowers the fraction of signaling cells at which one observes the characteristic power-law statistics of cluster sizes, consistent with our experimental results. We validate the model using a mutant biofilm whose signaling probability decays along the propagation direction. Our results reveal key statistical features of a correlated signaling process in a multicellular community. More broadly, our results identify extensions to percolation theory that do or do not alter its predictions and may be more appropriate for biological systems.

A statistical model for activation of Factor C by binding to LPS aggregates

Published data on Factor C activity at various LPS and Lipid A concentrations (Nakamura et al. in Eur J Biochem 176:89, 1988; Kobayashi et al. in J Biol Chem 37:25987, 2014) were rearranged to show that Factor C exhibited its maximum activity at a specific concentration of LPS. A statistical model was proposed for examining whether a single LPS molecule binding activates Factor C (monomeric activation) or dimerization of Factor C is necessary for the activation (dimeric activation). In the monomeric activation model the plots of the relative activity of Factor C against the molar ratio of LPS to Factor C were different from those in the published data. The plots in the dimeric activation model lie on a bell-shaped curve, whatever the Factor C concentration, matching the published data and indicating the appropriateness of that model. We suggest that Factor C is activated by multiple molecular interactions of Factor C with LPS aggregates on which it dimerises and that this explains why larger aggregates are less effective at activating Factor C than smaller ones.

Differences between primary central nervous system lymphoma and glioblastoma: topographic analysis using voxel-based morphometry

AIM

To evaluate the diagnostic feasibility of probabilistic analysis using voxel-based morphometry (VBM) in differentiating primary central nervous system lymphoma (PCNSL) from glioblastoma (GBM).

MATERIALS AND METHODS

In total, 118 patients with GBM (57 males, 61 females; mean [± standard deviation] age, 56.9±19.3 years; median, 61 years) and 52 patients with PCNSL (37 males, 15 females; mean age, 62±13.3 years, median, 66 years) were studied retrospectively. Each patient underwent preoperative contrast-enhanced T1-weighted imaging (CE-T1WI) using a 1.5 or 3 T magnetic resonance imaging (MRI) system. To assess preferential occurrence sites, images from CE-T1WI were co-registered and spatially normalised using the MNI152 T1 template. Subsequently, a region of interest (ROI) was placed in the centre of the enhancing tumour in normalised images with 1-mm isotropic resolution. The same ROI between normalised and T1 template images was set up using an ROI manager function in ImageJ software. A spherical volume of interest (VOI) with a radius of 10 mm was determined. A probability map was created by overlaying each image with the VOI. Each VOI was removed from T1 template images for VBM analysis. VBM analysis was performed using statistical parametric mapping (SPM) 12 software under default settings.

RESULTS

VBM analysis showed significantly higher frequency in the splenium of the corpus callosum among PCNSL patients than among GBM patients (p<0.05; family-wise error correction).

CONCLUSION

Topographic analysis using VBM provides useful information for differentiating PCNSL from GBM.

Intravoxel Incoherent Motion MR Imaging of Pediatric Intracranial Tumors: Correlation with Histology and Diagnostic Utility

BACKGROUND AND PURPOSE

Intravoxel incoherent motion imaging, which simultaneously measures diffusion and perfusion parameters, is promising for brain tumor grading. However, intravoxel incoherent motion imaging has not been tested in children. The purpose of this study was to evaluate the correlation between intravoxel incoherent motion parameters and histology to assess the accuracy of intravoxel incoherent motion imaging for pediatric intracranial tumor grading.

MATERIALS AND METHODS

Between April 2013 and September 2015, 17 children (11 boys, 6 girls; 2 months to 15 years of age) with intracranial tumors were included in this retrospective study. Intravoxel incoherent motion parameters were fitted using 13 b-values for a biexponential model. The perfusion-free diffusion coefficient, pseudodiffusion coefficient, and perfusion fraction were measured in high- and low-grade tumors. These intravoxel incoherent motion parameters and the ADC were compared using the unpaired t test. The correlations between the intravoxel incoherent motion parameters and microvessel density or the MIB-1 index were analyzed using the Spearman correlation test. Receiver operating characteristic analysis was used to evaluate diagnostic performance.

RESULTS

The perfusion-free diffusion coefficient and ADC were lower in high-grade than in low-grade tumors (perfusion-free diffusion coefficient, 0.85 ± 0.40 versus 1.53 ± 0.21 × 10^-3 mm²/s, P < .001; ADC, 1.04 ± 0.33 versus 1.60 ± 0.21 × 10^-3 mm²/s, P < .001). The pseudodiffusion coefficient showed no difference between the groups. The perfusion fraction was higher in high-grade than in low-grade tumors (21.7 ± 8.2% versus 7.6 ± 4.3%, P < .001). Receiver operating characteristic analysis found that the combined perfusion-free diffusion coefficient and perfusion fraction had the best diagnostic performance for tumor differentiation (area under the curve = 0.986).

CONCLUSIONS

Intravoxel incoherent motion imaging reflects tumor histology and may be a helpful, noninvasive method for pediatric intracranial tumor grading.

36 The effects of E-64 on the developmental competence of porcine oocytes vitrified at the germinal vesicle stage

Previous studies reported the activation of the apoptotic cascade by vitrification in mature porcine oocytes (Vallorani et al. 2012 Anim. Reprod. Sci. 135, 68-74) and that the cathepsin B inhibitor E-64 improved developmental competence of bovine oocytes via an antiapoptotic effect (Balboula et al. 2013 Reproduction 146, 407-417). The present study was carried out to test whether E-64 affected the developmental competency of porcine oocytes vitrified at the germinal vesicle stage. Cumulus-enclosed porcine oocytes were vitrified in microdrops and warmed by our method (Somfai et al. 2015 J. Reprod. Dev. 61, 571-579). Then, the oocytes were subjected to in vitro maturation (IVM) for 46h in a chemically defined porcine oocyte medium supplemented with 10ng mL−1 of epidermal growth factor, 10IU mL−1 of eCG, and 10IU mL−1 of hCG and during the first 22h of IVM with 1mM dibutyryl cyclic adenosine monophosphate. Then, cumulus-oocyte complexes were fertilized in vitro and presumptive zygotes were cultured in 50-µL drops of porcine zygote medium-3 for 7 days in 6-well dishes covered by paraffin oil in an atmosphere of 5% CO2, 5% O2, and 90% N2 at 39°C. On Day 5 (Day 0=IVF), the porcine zygote medium-3 was supplemented with 10% (vol/vol) FCS. The effects of 1.0μM of E-64 supplementation during IVM of non-vitrified and vitrified cumulus-oocyte complexes were investigated in a 2×2 factorial design. Survival rates after IVM, cleavage rates on Day 2, blastocyst rates, and total cell numbers in blastocysts on Day 7 were compared among groups. The experiment was replicated 5 times. Results were analysed by ANOVA and Tukey’s multiple comparison test. The percentages of live oocytes were statistically similar when oocytes were matured in the absence or presence of E-64 both in non-vitrified (99.2% v. 99.6%, respectively) and vitrified (94.3% v. 90.8%, respectively) groups. Similarly, IVM without or with E-64 supplementation had no effect on subsequent cleavage and blastocyst development rates in non-vitrified (67.4% v. 71.2% and 38.7% v. 43.2%, respectively) and vitrified (46.8% v. 48.8% and 14.6% v. 22.8%, respectively) oocytes. Irrespective of E-64 treatment, all survival and developmental rates in the vitrified groups were significantly lower (P&lt;0.05) compared with those of their non-vitrified counterparts except for the blastocyst development rate in the E-64-treated vitrified group, which did not differ significantly from those of the non-vitrified groups with or without E-64 treatment. There was no statistical difference in mean blastocyst cell numbers among the groups, ranging between 86.5±15.8 and 118±10.6. In conclusion, E-64 treatment had no effect on embryo production rates, which suggests that in our system, cathepsin-mediated apoptosis during IVM might not be the factor to limit embryo production using either fresh oocytes or those vitrified at the immature stage. This work was supported by JST/JICA SATREPS.

Signal Percolation within a Bacterial Community

Signal transmission among cells enables long-range coordination in biological systems. However, the scarcity of quantitative measurements hinders the development of theories that relate signal propagation to cellular heterogeneity and spatial organization. We address this problem in a bacterial community that employs electrochemical cell-to-cell communication. We developed a model based on percolation theory, which describes how signals propagate through a heterogeneous medium. Our model predicts that signal transmission becomes possible when the community is organized near a critical phase transition between a disconnected and a fully connected conduit of signaling cells. By measuring population-level signal transmission with single-cell resolution in wild-type and genetically modified communities, we confirm that the spatial distribution of signaling cells is organized at the predicted phase transition. Our findings suggest that at this critical point, the population-level benefit of signal transmission outweighs the single-cell level cost. The bacterial community thus appears to be organized according to a theoretically predicted spatial heterogeneity that promotes efficient signal transmission.

A Qualitative and Quantitative Correlation Study of Lumbar Intervertebral Disc Degeneration Using Glycosaminoglycan Chemical Exchange Saturation Transfer, Pfirrmann Grade, and T1-ρ

BACKGROUND AND PURPOSE

Glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging allows the direct measurement and mapping of glycosaminoglycans. In this study, we aimed to evaluate the usefulness of gagCEST imaging in the quantitative assessment of intervertebral disc degeneration in a comparison with Pfirrmann grade and T1-ρ measurements.

MATERIALS AND METHODS

Ninety-six lumbar intervertebral discs in 24 volunteers (36.0 ± 8.5 years of age, 21 men and 3 women) were examined with both gagCEST imaging and T1-ρ measurements. The gagCEST imaging was performed at 3T with a saturation pulse with 1.0-second duration and the B₁ amplitude of 0.8 μT followed by imaging by a 2D fast spin-echo sequence. The Z-spectra were obtained at 25 frequency offsets from -3 to +3 ppm (step, 0.25 ppm). A point-by-point B₀ correction was performed with a B₀ map. The gagCEST signal and T1-ρ values were measured in the nucleus pulposus in each intervertebral disc. The Pfirrmann grades were assessed on T2-weighted images.

RESULTS

The gagCEST signal at grade I (5.36% ± 2.79%) was significantly higher than those at Pfirrmann grade II (3.15% ± 1.40%, P = .0006), grade III (0.14% ± 1.03%, P < .0001), grade IV (-1.75% ± 2.82%, P < .0001), and grade V (-1.47% ± 0.36%, P < .0001). The gagCEST signal at grade II was significantly higher than those of grade III (P < .0001), grade IV (P < .0001), and grade V (P < .0001). The gagCEST signal was significantly correlated negatively with Pfirrmann grade (P < .0001) and positively correlated with T1-ρ (P < .0001).

CONCLUSIONS

GagCEST imaging could be a reliable and quantitative technique for assessing intervertebral disc degeneration.