70 research outputs found
A Learnable Counter-condition Analysis Framework for Functional Connectivity-based Neurological Disorder Diagnosis
To understand the biological characteristics of neurological disorders with
functional connectivity (FC), recent studies have widely utilized deep
learning-based models to identify the disease and conducted post-hoc analyses
via explainable models to discover disease-related biomarkers. Most existing
frameworks consist of three stages, namely, feature selection, feature
extraction for classification, and analysis, where each stage is implemented
separately. However, if the results at each stage lack reliability, it can
cause misdiagnosis and incorrect analysis in afterward stages. In this study,
we propose a novel unified framework that systemically integrates diagnoses
(i.e., feature selection and feature extraction) and explanations. Notably, we
devised an adaptive attention network as a feature selection approach to
identify individual-specific disease-related connections. We also propose a
functional network relational encoder that summarizes the global topological
properties of FC by learning the inter-network relations without pre-defined
edges between functional networks. Last but not least, our framework provides a
novel explanatory power for neuroscientific interpretation, also termed
counter-condition analysis. We simulated the FC that reverses the diagnostic
information (i.e., counter-condition FC): converting a normal brain to be
abnormal and vice versa. We validated the effectiveness of our framework by
using two large resting-state functional magnetic resonance imaging (fMRI)
datasets, Autism Brain Imaging Data Exchange (ABIDE) and REST-meta-MDD, and
demonstrated that our framework outperforms other competing methods for disease
identification. Furthermore, we analyzed the disease-related neurological
patterns based on counter-condition analysis
Autologous somatic cell nuclear transfer in pigs using recipient oocytes and donor cells from the same animal
The objective of the present study was to examine the feasibility of the production of autologous porcine somatic cell nuclear transfer (SCNT) blastocysts using oocytes and donor cells from slaughtered ovaries. Therefore, we attempted to optimize autologous SCNT by examining the effects of electrical fusion conditions and donor cell type on cell fusion and the development of SCNT embryos. Four types of donor cells were used: 1) denuded cumulus cells (DCCs) collected from in vitro-matured (IVM) oocytes; 2) cumulus cells collected from oocytes after 22 h of IVM and cultured for 18 h (CCCs); 3) follicular cells obtained from follicular contents and cultured for 40 h (CFCs); and 4) adult skin fibroblasts. The DCCs showed a significantly (p < 0.01) lower rate of fusion than the CCCs when two pulses of 170 V/mm DC were applied for 50 µsec (19 ± 2% vs. 77 ± 3%). The rate of DCC fusion with oocytes was increased by the application of two DC pulses of 190 V/mm for 30 µsec, although this was still lower than the rate of fusion in the CCCs (33 ± 1% vs. 80 ± 2%). The rates of cleavage (57 ± 5%) and blastocyst formation (1 ± 1%) in the DCC-derived embryos did not differ from those (55 ± 6% and 3 ± 1%, respectively) in the CCC-derived SCNT embryos. Autologous SCNT embryos derived from CFCs (5 ± 2%) showed higher levels of blastocyst formation (p < 0.01) than CCC-derived autologous SCNT embryos (1 ± 0%). In conclusion, the results of the present study show that culturing cumulus and follicular cells before SCNT enhances cell fusion with oocytes and that CFCs are superior to CCCs in the production of higher numbers of autologous SCNT blastocysts
Modification of maturation condition improves oocyte maturation and in vitro development of somatic cell nuclear transfer pig embryos
This study examined effects on the developmental competence of pig oocytes after somatic cell nuclear transfer (SCNT) or parthenogenetic activation (PA) of : 1) co-culturing of oocytes with follicular shell pieces (FSP) during in vitro maturation (IVM); 2) different durations of maturation; and 3) defined maturation medium supplemented with polyvinyl alcohol (PVA; control), pig follicular fluid (pFF), cysteamine (CYS), or β-mercaptoethanol (β-ME). The proportion of metaphase II oocytes was increased (p < 0.05) by co-culturing with FSP compared to control oocytes (98% vs. 94%). However, blastocyst formation after SCNT was not improved by FSP coculture (9% vs. 12%). Nuclear maturation of oocytes matured for 39 or 42 h was higher (p < 0.05) than that of oocytes matured for 36 h (95-96% vs. 79%). Cleavage (83%) and blastocyst formation (26%) were significantly higher (p < 0.05) in oocytes matured for 42 h than in other groups. Supplementation of a defined maturation medium with 100 µM CYS or 100 µM β-ME showed no stimulatory effect on oocyte maturation, embryo cleavage, or blastocyst formation after PA. β-ME treatment during IVM decreased embryo cleavage after SCNT compared to pFF or PVA treatments, but no significant difference was found in blastocyst formation (7-16%) among the four treatment groups. The results indicated that maturation of oocytes for 42 h was beneficial for the development of SCNT embryos. Furthermore, the defined maturation system used in this study could support in vitro development of PA or SCNT embryos
Production of cloned sei whale (Balaenoptera borealis) embryos by interspecies somatic cell nuclear transfer using enucleated pig oocytes
In this study, we examined the feasibility of using subzonal cell injection with electrofusion for interspecies somatic cell nuclear transfer (iSCNT) to produce sei whale embryos and to improve their developmental capacity by investigating the effect of osmolarity and macromolecules in the culture medium on the in vitro developmental capacity. Hybrid embryos produced by the electrofusion of fetal whale fibroblasts with enucleated porcine oocytes were cultured in modified porcine zygote medium-3 to examine the effects of osmolarity and fetal serum on their in vitro developmental capacity. More than 66% of the whale somatic cells successfully fused with the porcine oocytes following electrofusion. A portion (60~81%) of the iSCNT whale embryos developed to the two- to four-cell stages, but no embryos were able to reach the blastocyst stage. This developmental arrest was not overcome by increasing the osmolarity of the medium to 360 mOsm or by the addition of fetal bovine or fetal whale serum. Our results demonstrate that sei whale-porcine hybrid embryos may be produced by SCNT using subzonal injection and electrofusion. The pig oocytes partly supported the remodeling and reprogramming of the sei whale somatic cell nuclei, but they were unable to support the development of iSCNT whale embryos to the blastocyst stage
Tetraploid embryo aggregation produces high-quality blastocysts with an increased trophectoderm in pigs
Tetraploid complementation is an ideal method for demonstrating the differentiation potential of pluripotent stem cells. In this study, we selected the most efficient tetraploid production method for porcine embryos and investigated whether tetraploid blastomere aggregation could enhance the quality of tetraploid embryos. Three methods were investigated to produce tetraploid embryos: First, tetraploid embryos were produced using electro-fusion of two-cell stage parthenogenetic blastomere (FUTP). Second, somatic cell was injected into the mature oocyte and fused to produce tetraploid embryos. Third, oocytes were matured with Cytochalasin B (CB) for the late 22 h of in vitro maturation to inhibit the first polar body (PB1). Following that, non-PB1 oocytes were treated with CB for 4 h after parthenogenetic activation. There was no significant difference in the blastocyst development rate and tetraploid production rate of the embryos produced through the three methods. However, FUTP-derived blastocysts had a significantly lower percentage of apoptotic cells compared to other methods. The developmental competence of embryos, expression of trophectoderm cell marker genes, and distribution of YAP1 protein were investigated in tetraploid embryos produced using the FUTP method. The FUTP method most effectively prevented apoptosis during porcine tetraploid embryo formation. Tetraploid aggregation-derived blastocysts have a high proportion of trophectoderm with increased expression of the CDX2 mRNA and high YAP1 intensity. High-quality blastocysts derived from a tetraploid embryo aggregation can serve as suitable source material for testing the differentiation potential of pluripotent stem cells for blastocyst complementation in pigs
A comparative study on the efficiency of two enucleation methods in pig somatic cell nuclear transfer: Effects of the squeezing and the aspiration methods
In this study, two enucleation methods, the squeezing and the aspiration methods, were compared. The efficiency of these two methods to enucleate pig oocytes and the in vitro and in vivo viability of somatic cell nuclear transfer (SCNT) pig embryos, were evaluated. In the squeezing method, the zona pellucida was partially dissected and a small amount of cytoplasm containing metaphase II (MII) chromosomes and the first polar body (PB) were pushed out. In the aspiration method, the PB and MII chromosomes were aspirated using a beveled micropipette. After injection of fetal fibroblasts into the perivitelline space, reconstructed oocytes were fused and activated electrically, and then cultured in vitro for 6 days or transferred to surrogates. The squeezing method resulted in a higher proportion of degenerated oocytes than the aspiration method (14% vs. 5%). The squeezing method took longer to enucleate 100 oocytes (306 minutes) than the aspirating method (113 minutes). Fusion rate (72-78%) and cleavage rate (67%) were not influenced by the enucleation method but blastocyst formation was improved (P<0.05) in oocytes enucleated by the aspiration method (5 vs. 9%). When SCNT embryos were transferred to recipients, pregnancy rates to term were similar (27%, 3/11 and 27%, 3/11) in both methods with the birth of 10 piglets/3 litters and 16 piglets/3 litters in the squeezing and the aspiration methods, respectively. Our results indicate that the aspiration method for oocyte enucleation is more efficient than the squeezing method in producing a large number of pig SCNT embryos with normal in vivo viability
A unified framework for personalized regions selection and functional relation modeling for early MCI identification
Resting-state functional magnetic resonance imaging (rs-fMRI) has been widely adopted to investigate functional abnormalities in brain diseases. Rs-fMRI data is unsupervised in nature because the psychological and neurological labels are coarse-grained, and no accurate region-wise label is provided along with the complex co-activities of multiple regions. To the best of our knowledge, most studies regarding univariate group analysis or multivariate pattern recognition for brain disease identification have focused on discovering functional characteristics shared across subjects; however, they have paid less attention to individual properties of neural activities that result from different symptoms or degrees of abnormality. In this work, we propose a novel framework that can identify subjects with early-stage mild cognitive impairment (eMCI) and consider individual variability by learning functional relations from automatically selected regions of interest (ROIs) for each subject concurrently. In particular, we devise a deep neural network composed of a temporal embedding module, an ROI selection module, and a disease-identification module. Notably, the ROI selection module is equipped with a reinforcement learning mechanism so it adaptively selects ROIs to facilitate the learning of discriminative feature representations from a temporally embedded blood-oxygen-level-dependent signals. Furthermore, our method allows us to capture the functional relations of a subject-specific ROI subset through the use of a graph-based neural network. Our method considers individual characteristics for diagnosis, as opposed to most conventional methods that identify the same biomarkers across subjects within a group. Based on the ADNI cohort, we validate the effectiveness of our method by presenting the superior performance of our network in eMCI identification. Furthermore, we provide insightful neuroscientific interpretations by analyzing the regions selected for the eMCI classification
Effect of Thermal Abuse Conditions on Thermal Runaway of NCA 18650 Cylindrical Lithium-Ion Battery
In energy storage systems and electric vehicles utilizing lithium-ion batteries, an internal short circuit or a thermal runaway (TR) may result in fire-related accidents. Particularly, under non-oxygenated conditions, a fire can spread as a result of TR. In this study, a TR experiment was performed on a nickel–cobalt–aluminum 18650 cylindrical lithium-ion battery via thermal conduction. The time required to attain TR (temperature range: 250–500 °C) was drastically reduced from approximately 1200 s to 1 s. The chemical reaction rate of thermal runaway was classified according to temperature into two global mechanisms and applied to the Arrhenius equation, thereby yielding a correlation between plate temperature (TP) and time difference of TR times ∆t (i.e., t1−t0 or t2−t0). As a result, activation energy for the overall reaction of the TR was estimated to be 39.9 kJ/mol. Furthermore, the safety guarantee time mandated by the safety regulation for vehicle batteries is 5 min; an analysis of the experiment results reveals that the following conditions can be satisfied: TP = 308.4 °C, Δtt1−t0 = 5 min; TP = 326.2 °C, Δtt2−t0 = 5 min. The experiment results offer a scientific basis for predicting the time of occurrence of TR and establishing safety standards
A Comparative Study on the Efficiency of Two Enucleation Methods in Pig Somatic Cell Nuclear Transfer: Effects of the Squeezing and the Aspiration Methods
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