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220 result(s) for "Nam, Sang-Yoon"
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Titanium dioxide nanoparticles oral exposure to pregnant rats and its distribution
Background Titanium dioxide (TiO 2 ) nanoparticles are among the most manufactured nanomaterials in the industry, and are used in food products, toothpastes, cosmetics and paints. Pregnant women as well as their conceptuses may be exposed to TiO 2 nanoparticles; however, the potential effects of these nanoparticles during pregnancy are controversial, and their internal distribution has not been investigated. Therefore, in this study, we investigated the potential effects of oral exposure to TiO 2 nanoparticles and their distribution during pregnancy. TiO 2 nanoparticles were orally administered to pregnant Sprague-Dawley rats (12 females per group) from gestation days (GDs) 6 to 19 at dosage levels of 0, 100, 300 and 1000 mg/kg/day, and then cesarean sections were conducted on GD 20. Results In the maternal and embryo-fetal examinations, there were no marked toxicities in terms of general clinical signs, body weight, food consumption, organ weights, macroscopic findings, cesarean section parameters and fetal morphological examinations. In the distribution analysis, titanium contents were increased in the maternal liver, maternal brain and placenta after exposure to high doses of TiO 2 nanoparticles. Conclusion Oral exposure to TiO 2 during pregnancy increased the titanium concentrations in the maternal liver, maternal brain and placenta, but these levels did not induce marked toxicities in maternal animals or affect embryo-fetal development. These results could be used to evaluate the human risk assessment of TiO 2 nanoparticle oral exposure during pregnancy, and additional comprehensive toxicity studies are deemed necessary considering the possibility of complex exposure scenarios and the various sizes of TiO 2 nanoparticles.
Knockout rat models mimicking human atherosclerosis created by Cpf1-mediated gene targeting
The rat is a time-honored traditional experimental model animal, but its use is limited due to the difficulty of genetic modification. Although engineered endonucleases enable us to manipulate the rat genome, it is not known whether the newly identified endonuclease Cpf1 system is applicable to rats. Here we report the first application of CRISPR-Cpf1 in rats and investigate whether Apoe knockout rat can be used as an atherosclerosis model. We generated Apoe- and/or Ldlr -deficient rats via CRISPR-Cpf1 system, characterized by high efficiency, successful germline transmission, multiple gene targeting capacity, and minimal off-target effect. The resulting Apoe knockout rats displayed hyperlipidemia and aortic lesions. In partially ligated carotid arteries of rats and mice fed with high-fat diet, in contrast to Apoe knockout mice showing atherosclerotic lesions, Apoe knockout rats showed only adventitial immune infiltrates comprising T lymphocytes and mainly macrophages with no plaque. In addition, adventitial macrophage progenitor cells (AMPCs) were more abundant in Apoe knockout rats than in mice. Our data suggest that the Cpf1 system can target single or multiple genes efficiently and specifically in rats with genetic heritability and that Apoe knockout rats may help understand initial-stage atherosclerosis.
PIBF1 regulates trophoblast syncytialization and promotes cardiovascular development
Proper placental development in early pregnancy ensures a positive outcome later on. The developmental relationship between the placenta and embryonic organs, such as the heart, is crucial for a normal pregnancy. However, the mechanism through which the placenta influences the development of embryonic organs remains unclear. Trophoblasts fuse to form multinucleated syncytiotrophoblasts (SynT), which primarily make up the placental materno-fetal interface. We discovered that endogenous progesterone immunomodulatory binding factor 1 (PIBF1) is vital for trophoblast differentiation and fusion into SynT in humans and mice. PIBF1 facilitates communication between SynT and adjacent vascular cells, promoting vascular network development in the primary placenta. This process affected the early development of the embryonic cardiovascular system in mice. Moreover, in vitro experiments showed that PIBF1 promotes the development of cardiovascular characteristics in heart organoids. Our findings show how SynTs organize the barrier and imply their possible roles in supporting embryogenesis, including cardiovascular development. SynT-derived factors and SynT within the placenta may play critical roles in ensuring proper organogenesis of other organs in the embryo. The genetic link between placenta function and congenital heart defects has been established, though the cellular mechanisms underlying this connection is less clear. Here they show that PIBF1 regulates syncytiotrophoblast fusion and that loss of PIBF1 also negatively impacts heart development, providing a potential link between the development of these two organs.
Analysis of factors affecting reversal of Hartmann’s procedure and post-reversal complications
Although Hartmann’s procedure (HP) is commonly used as emergency treatment for colorectal disease, the reversal of HP (HR) is infrequently performed. The aims were to evaluate the rate of HR and determine the factors predictive of achieving HR. We retrospectively reviewed the medical records of patients who underwent HP between January 2007 and June 2019 at six Hallym University-affiliated hospitals. Multivariable analysis was performed to identify which factors were independently associated with HR. In the study period, 437 patients underwent HP, and 127 (29.0%) subsequently underwent HR. Of these, 46 (35.9%) patients experienced post-HR complications. In multivariable analysis, an interval between HP and HR of > 6 months was associated with the only lower rate of post-HR complications. Multivariate analysis showed that HR was less likely in patients aged > 70 years, those with American Society of Anesthesiologists (ASA) class III or IV, elective surgery, those experiencing more than two HP-related complications, and those with a malignancy (an indication for HP). One-third of the patients underwent HR. Age > 70 years, ASA class III or IV, elective surgery, more than two HP-related complications, and malignancy were associated with a non-HR rate.
Lipid signatures reflect the function of the murine primary placentation
The placenta regulates maternal-fetal communication, and its defect leads to significant pregnancy complications. The maternal and embryonic circulations are primitively connected in early placentation, but the function of the placenta during this developmentally essential period is relatively unknown. We thus performed a comparative proteomic analysis of the placenta before and after primary placentation and found that the metabolism and transport of lipids were characteristically activated in this period. The placental fatty acid (FA) carriers in specific placental compartments were upregulated according to gestational age, and metabolomic analysis also showed that the placental transport of FAs increased in a time-dependent manner. Further analysis of two mutant mice models with embryonic lethality revealed that lipid-related signatures could reflect the functional state of the placenta. Our findings highlight the importance of the nutrient transport function of the primary placenta in the early gestational period and the role of lipids in embryonic development. Summary Sentence The placenta is activated characteristically in terms of lipid transport during primary placentation, and the lipid-related signatures closely reflect the functional state of the placenta.
Protection of Lycopene against Embryonic Anomalies and Yolk Sac Placental Vasculogenic Disorders Induced by Nicotine Exposure
Identification of a new agent from natural products for the protection of embryonic anomalies is potentially valuable. To investigate the protective effect exerted by lycopene against nicotine-induced malformations, mouse embryos in embryonic day 8.5 with yolk sac placentas were cocultured with 1 mM nicotine and/or lycopene (1×10−6, 1×10−5 μM) for 48 h. The morphological defects and apoptotic cell deaths in the embryo and yolk sac placenta of the nicotine group were significantly increased. Exposure to nicotine resulted in reduced superoxide dismutase (SOD) activity and cytoplasmic SOD and cytoplasmic glutathione peroxidase mRNA levels, but increased lipid peroxidation level in embryos. Moreover, treatment with nicotine resulted in aggravated expressions of the mRNA or protein level of antiapoptotic (BCL2-associated X protein, B-cell lymphoma-extralarge, and caspase 3), anti-inflammatory (nuclear factor kappa-light-chain-enhancer of activated B cells and tumor necrosis factor-alpha), and vasculogenic (vascular endothelial growth factor-alpha, insulin-like growth factor-1, alpha smooth muscle actin, transforming growth factor-beta 1, and hypoxia inducible factor-1 alpha) factors in the embryo and yolk sac placenta. However, all the parameters were significantly improved by treatment with lycopene, as compared to the nicotine group. These findings indicate the potential of lycopene as a protective agent against embryonic anomalies and yolk sac vasculogenic and placenta-forming defects induced by nicotine through modulations of oxidative, apoptotic, vasculogenic, and inflammatory activities.
Inhibitory effect of 4-O-methylhonokiol on lipopolysaccharide-induced neuroinflammation, amyloidogenesis and memory impairment via inhibition of nuclear factor-kappaB in vitro and in vivo models
Background Neuroinflammation is important in the pathogenesis and progression of Alzheimer disease (AD). Previously, we demonstrated that lipopolysaccharide (LPS)-induced neuroinflammation caused memory impairments. In the present study, we investigated the possible preventive effects of 4- O -methylhonokiol, a constituent of Magnolia officinalis , on memory deficiency caused by LPS, along with the underlying mechanisms. Methods We investigated whether 4- O -methylhonokiol (0.5 and 1 mg/kg in 0.05% ethanol) prevents memory dysfunction and amyloidogenesis on AD model mice by intraperitoneal LPS (250 μg/kg daily 7 times) injection. In addition, LPS-treated cultured astrocytes and microglial BV-2 cells were investigated for anti-neuroinflammatory and anti-amyloidogenic effect of 4- O -methylhonkiol (0.5, 1 and 2 μM). Results Oral administration of 4- O -methylhonokiol ameliorated LPS-induced memory impairment in a dose-dependent manner. In addition, 4- O -methylhonokiol prevented the LPS-induced expression of inflammatory proteins; inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as activation of astrocytes (expression of glial fibrillary acidic protein; GFAP) in the brain. In in vitro study, we also found that 4- O -methylhonokiol suppressed the expression of iNOS and COX-2 as well as the production of reactive oxygen species, nitric oxide, prostaglandin E 2 , tumor necrosis factor-α, and interleukin-1β in the LPS-stimulated cultured astrocytes. 4- O -methylhonokiol also inhibited transcriptional and DNA binding activity of NF-κB via inhibition of IκB degradation as well as p50 and p65 translocation into nucleus of the brain and cultured astrocytes. Consistent with the inhibitory effect on neuroinflammation, 4- O -methylhonokiol inhibited LPS-induced Aβ 1-42 generation, β- and γ-secretase activities, and expression of amyloid precursor protein (APP), BACE1 and C99 as well as activation of astrocytes and neuronal cell death in the brain, in cultured astrocytes and in microglial BV-2 cells. Conclusion These results suggest that 4- O -methylhonokiol inhibits LPS-induced amyloidogenesis via anti-inflammatory mechanisms. Thus, 4- O -methylhonokiol can be a useful agent against neuroinflammation-associated development or the progression of AD.
MD-2 as the Target of Nonlipid Chalcone in the Inhibition of Endotoxin LPS-Induced TLR4 Activity
Myeloid differentiation 2 (MD-2) recognizes endotoxin lipopolysaccharide (LPS), which is required for Tolllike receptor 4 (TLR4) activity. MD-2 represents a more attractive therapeutic target than TLR4 for intervention in severe inflammatory disorders due to microbial infection. Here, we suggest MD-2 as a molecular target of nonlipid chalcone in the inhibition of LPS-induced cellular inflammation. A chalcone derivative, 2,4-dihydroxy-6-isopentyloxychalcone (JSH) competitively displaced LPS from MD-2, and was fitted into the ligand-binding site on the crystal structure of MD-2 under the most energetically favorable simulation. JSH nullified TLR4 activation mechanism and sequentially inhibited nuclear factor-(NF-ºB) activation that involves the phosphorylation and degradation of inhibitory ºBS and the nuclear import and transcriptional activity of NF-ºA in LPS-activated macrophages. Moreover, JSH suppressed NF-KB-target inflammatory genes such as inducible nitric oxide synthase, cyclooxygenase-2, interleukin-1β (IL-1β) and IL-6. Taken together, this study assigns the chalcone structure as an LPS antagonist binding to MD-2 with therapeutic potential against inflammatory conditions.
Protective effect of the ethanol extract of Magnolia officinalis and 4-O-methylhonokiol on scopolamine-induced memory impairment and the inhibition of acetylcholinesterase activity
Magnolol, honokiol, and obovatol are well-known bioactive constituents of the bark of Magnolia officinalis and have been used as traditional Chinese medicines for the treatment of neurosis, anxiety, and stroke. We recently isolated novel active compound (named 4- O -methylhonokiol) from the ethanol extract of Magnolia officinalis . The present study aimed to test two different doses of ethanol extracts of Magnolia officinalis (5 and 10 mg/kg/mouse, p.o., 1 week) and 4- O -methylhonokiol (0.75 and 1.5 mg/kg/mouse, p.o., 1 week) administered for 7 days on memory impairment induced by scopolamine (1 mg/kg body weight i.p.) in mice. Memory and learning were evaluated using the Morris water maze and the step-down avoidance test. Both the ethanol extract of Magnolia officinalis and 4- O -methylhonokiol prevented memory impairment induced by scopolamine in a dose-dependent manner. The ethanol extract of Magnolia officinalis and 4- O -methylhonokiol also dose-dependently attenuated the scopolamine-induced increase of acetylcholinesterase (AChE) activity in the cortex and hippocampus of mice, and inhibited AChE activity in vitro with IC 50 (12 nM). This study, therefore, suggests that the ethanol extract of Magnolia officinalis and its major ingredient, 4- O -methylhonokiol, may be useful for the prevention of the development or progression of AD.
Alleviation of Kainic Acid-Induced Brain Barrier Dysfunction by 4-O-Methylhonokiol in In Vitro and In Vivo Models
This experiment was designed to investigate whether 4-O-methylhonokiol (MH), a principal ingredient of Magnolia (M.) officinalis bark, alleviated acute intraperitoneal (i.p.) kainic acid- (KA-) induced brain blood barrier dysfunction (BBBD) via pathological examination and cytological analyses of the brain tissues of mice. KA (10–30 mg/kg) time- and dose-dependently increased the water content of brain tissues and induced edema and encephalopathy. However, pretreatment with MH (5 and 20 mg/kg, i.p.) significantly reduced the water content of the brain compared to that observed in the KA control group. Furthermore, MH significantly and dose-dependently reversed the remarkable variations in evan’s blue dye (EBD) staining and malondialdehyde (MDA) levels that were induced by KA (10 mg/kg, i.p.). MH also decreased the elevated seizure scores that were induced by KA (10 mg/kg, i.p.) in mice in a manner similar to scavengers such as DMTU and trolox. Additionally, MH significantly scavenged intracellular ROS and Ca2+ within hippocampal cells. The tight junction seals mediated by claudin (Cld-5) were also found to be modulated by MH. MH efficiently reduced 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50, 52.4 mM) and •OH with an electron spin resonance (ESR) signal rate constant of 4 × 10 9 M - 1 · S - 1 , which is close to the reactivity of the vitamin E analog trolox. Taken together, these results suggest that MH may enhance radical scavenging in lipid and hydrophobic environments, which may be important for the physiological activity of the barrier.