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STUDY QUESTION: Can exposure to palmitic acid (PA), a common saturated fatty acid, modulate autophagy in both human and mouse trophoblast cells through the regulation of acyl-coenzyme A-binding protein (ACBP)? SUMMARY ANSWER: PA exposure before and during pregnancy impairs placental development through mechanisms involving placental autophagy and ACBP expression. WHAT IS KNOWN ALREADY: High-fat diets, including PA, have been implicated in adverse effects on human placental and fetal development. Despite this recognition, the precise molecular mechanisms underlying these effects are not fully understood. STUDY DESIGN, SIZE, DURATION: Extravillous trophoblast (EVT) cell line HTR-8/SVneo and human trophoblast stem cell (hTSC)-derived EVT (hTSCs-EVT) were exposed to PA or vehicle control for 24 h. Female wild-type C57BL/6 mice were divided into PA and control groups (n = 10 per group) and subjected to a 12-week dietary intervention. Afterward, they were mated with male wild-type C57BL/6 mice and euthanized on Day 14 of gestation. Female ACBPflox/flox mice were also randomly assigned to control and PA-exposed groups (each with 10 mice), undergoing the same dietary intervention and mating with ACBPflox/floxELF5-Cre male mice, followed by euthanasia on Day 14 of gestation. The study assessed the effects of PA on mouse embryonic development and placental autophagy. Additionally, the role of ACBP in the pathogenesis of PA-induced placental toxicity was investigated. PARTICIPANTS/MATERIALS, SETTING, METHODS: The findings were validated using real-time PCR, Western blot, immunofluorescence, transmission electron microscopy, and shRNA knockdown approaches. MAIN RESULTS AND THE ROLE OF CHANCE: Exposure to PA-upregulated ACBP expression in both human HTR-8/SVneo cells and hTSCs-EVT, as well as in mouse placenta. PA exposure also induced autophagic dysfunction in HTR-8/SVneo cells, hTSCs-EVT, and mouse placenta. Through studies on ACBP placental conditional knockout mice and ACBP knockdown human trophoblast cells, it was revealed that reduced ACBP expression led to trophoblast malfunction and affected the expression of autophagy-related proteins LC3B-II and P62, thereby impacting embryonic development. Conversely, ACBP knockdown partially mitigated PA-induced impairment of placental trophoblast autophagy, observed both in vitro in human trophoblast cells and in vivo in mice. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Primary EVT cells from early pregnancy are fragile, limiting research use. Maintaining their viability is tough, affecting data reliability. The study lacks depth to explore PA diet cessation effects after 12 weeks. Without follow-up, understanding postdiet impacts on pregnancy stages is incomplete. Placental abnormalities linked to elevated PA diet in embryos lack confirmation due to absence of control groups. Clarifying if issues stem solely from PA exposure is difficult without proper controls. WIDER IMPLICATIONS OF THE FINDINGS: Consuming a high-fat diet before and during pregnancy may result in complications or challenges in successfully carrying the pregnancy to term. It suggests that such dietary habits can have detrimental effects on the health of both the mother and the developing fetus. STUDY FUNDING/COMPETING INTEREST(S): This work was supported in part by the National Natural Science Foundation of China (82171664, 82301909) and the Natural Science Foundation of Chongqing Municipality of China (CSTB2022NS·CQ-LZX0062, cstc2019jcyj-msxmX0749, and cstc2021jcyj-msxmX0236). The authors declare that they have no conflict of interest. TRIAL REGISTRATION NUMBER: N/A.
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PURPOSE: Fetal growth restriction (FGR) is a common complication characterized by impaired placental function and unfavorable pregnancy outcomes. This study aims to elucidate the expression pattern of miR-181d-5p in FGR placentas and explore its effects on trophoblast fusion. METHODS: The expression pattern of miR-181d-5p in human FGR placentas were evaluated using qRT-PCR. Western blot, qRT-PCR, and Immunofluorescence analysis were performed in a Forskolin (FSK)-induced BeWo cell fusion model following the transfection of miR-181d-5p mimic or inhibitor. Potential target genes for miR-181d-5p were identified by screening miRNA databases. The interaction between miR-181d-5p and Luman/CREB3 Recruitment Factor (CREBRF) was determined through a luciferase assay. Moreover, the effect of CREBRF on BeWo cell fusion was examined under hypoxic conditions. RESULTS: Aberrant up-regulation of miR-181d-5p and altered expression of trophoblast fusion makers, including glial cell missing 1 (GCM1), Syncytin1 (Syn1), and E-cadherin (ECAD), were found in human FGR placentas. A down-regulation of miR-181d-5p expression was observed in the FSK-induced BeWo cell fusion model. Transfection of the miR-181d-5p mimic resulted in the inhibition of BeWo cell fusion, characterized by a down-regulation of GCM1 and Syn1, accompanied by an up-regulation of ECAD. Conversely, the miR-181d-5p inhibitor promoted BeWo cell fusion. Furthermore, miR-181d-5p exhibited negative regulation of CREBRF, which was significantly down-regulated in the hypoxia-induced BeWo cell model. The overexpression of CREBRF was effectively ameliorated the impaired BeWo cell fusion induced by hypoxia. CONCLUSIONS: Our study demonstrated that miR-181d-5p, which is elevated in FGR placenta, inhibited the BeWo cell fusion through negatively regulating the expression of CREBRF.
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MicroARNs , Placenta , Humanos , Femenino , Embarazo , Placenta/metabolismo , Trofoblastos/metabolismo , Retardo del Crecimiento Fetal/genética , MicroARNs/genética , MicroARNs/metabolismo , Hipoxia/genética , Hipoxia/metabolismo , Proliferación Celular/genéticaRESUMEN
PROBLEM: Natural killer (NK) cells from the peripheral blood and spleen represent the source from which various tissues replenish their immune cell populations. Hyperandrogenism and high interleukin-2 (IL-2) levels are factors present in polycystic ovary syndrome (PCOS). These factors and metformin, one of the commonest medications used in treating PCOS, may have an impact on NK cells. However, this is presently unknown. Here, we aimed to assess the distribution of peripheral blood and splenic NK cells and their CD2 and CD94 expression patterns in a PCOS mouse model and test whether metformin could reverse these effects. METHOD OF STUDY: Four mouse groups were designed as follows (n = 15/group): control, PCOS, PCOS plus vehicle, PCOS plus metformin. Dehydroepiandrosterone and a high-fat diet were administered to induce the PCOS mouse model. Flow cytometry was used to analyze the expressions of CD2 and CD94 on peripheral blood and splenic NK cells. RESULTS: PCOS mice had a low surface-density of CD2 on peripheral blood NK cells and a decreased percentage of CD2+ splenic NK cells. Metformin administration did not significantly influence these changes; however, it reduced the splenic NK cell counts. CONCLUSIONS: Our findings proved the association of PCOS with an altered expression of CD2 on peripheral blood and splenic NK cells and that of metformin with a lowered splenic NK cell reserve in PCOS conditions. These findings could further unlock key mechanisms in PCOS pathophysiology and in the mechanism of action of metformin, towards improving PCOS management.
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Resistencia a la Insulina , Metformina , Síndrome del Ovario Poliquístico , Animales , Modelos Animales de Enfermedad , Femenino , Humanos , Hipoglucemiantes/farmacología , Hipoglucemiantes/uso terapéutico , Células Asesinas Naturales , Metformina/farmacología , Metformina/uso terapéutico , RatonesRESUMEN
Objective: To explore the effects of hydroxyacyl-CoA dehydrogenase alpha subunit (HADHA) on the migration and invasion of HTR-8/SVneo cells, a human trophoblast cell line, and its potential mechanism of action. Methods: Immunofluorescence staining was done to evaluate the expression levels of HADHA in samples of normal villi and recurrent spontaneous abortion (RSA) villi at 6-8 weeks. Lentiviral infection system was used to construct stable HTR-8/SVneo cell lines with HADHA overexpression and knockdown. Western blot, qRT-PCR, Wound-healing assay, and Transwell assay were used to determine the effect of HADHA on the migration and invasion of HTR-8/SVneo cells and the expression of relevant genes. Transcriptome sequencing and bioinformatics analysis were done to screen for the potential target genes and signaling pathways regulated by HADHA. The specific molecular mechanism of how HADHA regulates the migration and invasion of HTR-8/SVneo cells was examined by adding the inhibitor of protein kinase B (PKB/AKT). Results: HADHA was highly expressed in extravillous trophoblasts (EVT) of RSA villus samples as compared with samples from the normal control group. In HTR-8/SVneo cells overexpressing HADHA, the expression levels of migration and invasion-related genes, including HLA-G, MMP2, MMP9, and NCAD, were decreased (P<0.01,P<0.05), and the migration and invasion abilities of HTR-8/SVneo cells were weakened (P<0.05). HADHA knockdown increased the expression levels of HLA-G, MMP2, MMP9, and NCAD (P<0.01, P<0.05), and promoted the migration and invasion of HTR-8/SVneo cells (P<0.05). In addition, HADHA overexpression decreased the phosphorylation levels of PI3K and AKT (P<0.05) and inhibited the PI3K/AKT signaling pathway. HADHA knockdown activated the PI3K/AKT signaling pathway. When MK-2206, an AKT inhibitor, was added to stable HTR-8/SVneo cell lines with HADHA knockdown, the migration and invasion of the cells were significantly reduced. Conclusion: HADHA inhibits the migration and invasion of HTR-8/SVneo cells by inhibiting the PI3K/AKT signaling pathway.
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Preeclampsia , Proteínas Proto-Oncogénicas c-akt , Movimiento Celular/fisiología , Coenzima A/metabolismo , Coenzima A/farmacología , Femenino , Antígenos HLA-G/metabolismo , Antígenos HLA-G/farmacología , Humanos , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Subunidad alfa de la Proteína Trifuncional Mitocondrial/metabolismo , Oxidorreductasas/metabolismo , Oxidorreductasas/farmacología , Fosfatidilinositol 3-Quinasas/metabolismo , Embarazo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Trofoblastos/metabolismoRESUMEN
The syncytiotrophoblast, derived from cytotrophoblast fusion, is responsible for maternal-fetal exchanges, secretion of pregnancy-related hormones, and fetal defense against pathogens. Inadequate cytotrophoblast fusion can lead to pregnancy disorders, such as preeclampsia and fetal growth restriction. However, little is known about the mechanism of cytotrophoblast fusion in both physiological and pathological pregnancy conditions. In this study, P57kip2 (P57), a cell cycle-dependent kinase inhibitor that negatively regulates the cell cycle, was found to be up-regulated during the process of syncytialization in both primary trophoblast cells and BeWo cells. Co-immunofluorescence with proliferation markers Ki67 and Cyclin-CDK factors further showed that P57 specifically localizes in the post-mitotic cytotrophoblast subtype of the early pregnancy villi. Overexpression of P57 promoted trophoblast syncytialization by arresting the cell cycle at the G1/G0 phase and inhibiting proliferation. Blocking of the cell cycle through a serum starvation culture resulted in an enhancement of cytotrophoblast fusion and the up-regulation of P57. In both spontaneous cytotrophoblast fusion and forskolin-induced BeWo cell fusion models, an initial up-regulation of P57 was observed followed by a subsequent down-regulation. These findings indicate that proper expression of P57 at cytotrophoblast differentiation nodes plays an important role in trophoblast syncytialization.
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Puntos de Control del Ciclo Celular , Inhibidor p57 de las Quinasas Dependientes de la Ciclina/metabolismo , Placenta/fisiología , Trofoblastos/fisiología , Fusión Celular , Inhibidor p57 de las Quinasas Dependientes de la Ciclina/genética , Femenino , Humanos , Placenta/citología , Embarazo , Trofoblastos/citologíaRESUMEN
BACKGROUND: In the realm of assisted reproduction, a subset of infertile patients demonstrates high ovarian response following controlled ovarian stimulation (COS), with approximately 29.7% facing the risk of Ovarian Hyperstimulation Syndrome (OHSS). Management of OHSS risk often necessitates embryo transfer cancellation, leading to delayed prospects of successful pregnancy and significant psychological distress. Regrettably, these patients have received limited research attention, particularly regarding their metabolic profile. In this study, we aim to utilize gas chromatography-mass spectrometry (GC-MS) to reveal these patients' unique serum metabolic profiles and provide insights into the disease's pathogenesis. METHODS: We categorized 145 infertile women into two main groups: the CON infertility group from tubal infertility patients and the Polycystic Ovary Syndrome (PCOS) infertility group. Within these groups, we further subdivided them into four categories: patients with normal ovarian response (CON-NOR group), patients with high ovarian response and at risk for OHSS (CON-HOR group) within the CON group, as well as patients with normal ovarian response (PCOS-NOR group) and patients with high ovarian response and at risk for OHSS (PCOS-HOR group) within the PCOS group. Serum metabolic profiles were analyzed using GC-MS. The risk criteria for OHSS were: the number of developing follicles > 20, peak Estradiol (E2) > 4000pg/mL, and Anti-Müllerian Hormone (AMH) levels > 4.5ng/mL. RESULTS: The serum metabolomics analysis revealed four different metabolites within the CON group and 14 within the PCOS group. Remarkably, 10-pentadecenoic acid emerged as a discernible risk metabolite for the CON-HOR, also found to be a differential metabolite between CON-NOR and PCOS groups. cysteine and 5-methoxytryptamine were also identified as risk metabolites for the PCOS-HOR. Furthermore, KEGG analysis unveiled significant enrichment of the aminoacyl-tRNA biosynthesis pathway among the metabolites differing between PCOS-NOR and PCOS-HOR. CONCLUSION: Our study highlights significant metabolite differences between patients with normal ovarian response and those with high ovarian response and at risk for OHSS within both the tubal infertility control group and PCOS infertility group. Importantly, we observe metabolic similarities between patients with PCOS and those with a high ovarian response but without PCOS, suggesting potential parallels in their underlying causes.
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Fertilización In Vitro , Infertilidad Femenina , Inducción de la Ovulación , Humanos , Femenino , Infertilidad Femenina/metabolismo , Infertilidad Femenina/sangre , Adulto , Síndrome de Hiperestimulación Ovárica/sangre , Síndrome de Hiperestimulación Ovárica/metabolismo , Síndrome del Ovario Poliquístico/metabolismo , Síndrome del Ovario Poliquístico/sangre , Síndrome del Ovario Poliquístico/complicaciones , Cromatografía de Gases y Espectrometría de Masas , Metaboloma , Metabolómica/métodos , Embarazo , Ovario/metabolismoRESUMEN
In this retrospective study conducted at Sichuan Jinxin Xinan Women and Children's Hospital spanning January 2015 to December 2021, our objective was to investigate the impact of embryo cryopreservation duration on outcomes in frozen embryo transfer. Participants, totaling 47,006 cycles, were classified into 3 groups based on cryopreservation duration: ≤1 year (Group 1), 1 to 6 years (Group 2), andâ ≥6 years (Group 3). Employing various statistical analyses, including 1-way ANOVA, Kruskal-Wallis test, chi-square test, and a generalized estimating equation model, we rigorously adjusted for confounding factors. Primary outcomes encompassed clinical pregnancy rate and Live Birth Rate (LBR), while secondary outcomes included biochemical pregnancy rate, multiple pregnancy rate, ectopic pregnancy rate, early and late miscarriage rates, preterm birth rate, neonatal birth weight, weeks at birth, and newborn sex. Patient distribution across cryopreservation duration groups was as follows: Group 1 (40,461 cycles), Group 2 (6337 cycles), and Group 3 (208 cycles). Postcontrolling for confounding factors, Group 1 exhibited a decreased likelihood of achieving biochemical pregnancy rate, clinical pregnancy rate, and LBR (ORâ <â 1, aORâ <â 1, Pâ <â .05). Furthermore, an elevated incidence of ectopic pregnancy was observed (ORâ >â 1, aORâ >â 1), notably significant after 6 years of freezing time [aORâ =â 4.141, 95% confidence intervals (1.013-16.921), Pâ =â .05]. Cryopreservation exceeding 1 year was associated with an increased risk of early miscarriage and preterm birth (ORâ >â 1, aORâ >â 1). No statistically significant differences were observed in birth weight or sex between groups. However, male infant birth rates were consistently higher than those of female infants across all groups. In conclusion, favorable pregnancy outcomes align with embryo cryopreservation durations within 1 year, while freezing for more than 1 year may diminish clinical pregnancy and LBRs, concurrently elevating the risk of ectopic pregnancy and preterm birth.
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Aborto Espontáneo , Embarazo Ectópico , Nacimiento Prematuro , Niño , Embarazo , Femenino , Masculino , Recién Nacido , Humanos , Resultado del Embarazo/epidemiología , Estudios Retrospectivos , Aborto Espontáneo/epidemiología , Aborto Espontáneo/etiología , Peso al Nacer , Nacimiento Prematuro/epidemiología , Nacimiento Prematuro/etiología , Nacimiento Vivo , Transferencia de Embrión/efectos adversos , Índice de Embarazo , Criopreservación , Embarazo Ectópico/epidemiología , Embarazo Ectópico/etiologíaRESUMEN
OBJECTIVE: This study aimed to evaluate the effects of the home quarantine on pregnancy outcomes of gestational diabetes mellitus (GDM) patients during the COVID-19 outbreak. METHODS: The complete electronic medical records of patients with GDM with home quarantine history were collected and classified into the home quarantine group from 24 February 2020 to 24 November 2020. The same period of patients with GDM without home quarantine history were included in the control group from 2018 to 2019. The pregnant outcomes of the home quarantine and control groups were systematically compared, such as neonatal weight, head circumference, body length, one-minute Apgar score, fetal macrosomia, and pre-term delivery. RESULTS: A total of 1358 patients with GDM were included in the analysis, including 484 in 2018, 468 in 2019, and 406 in 2020. Patients with GDM with home quarantine in 2020 had higher glycemic levels and adverse pregnancy outcomes than in 2018 and 2019, including higher cesarean section rates, lower Apgar scores, and higher incidence of macrosomia and umbilical cord around the neck. More importantly, the second trimester of home quarantine had brought a broader impact on pregnant women and fetuses. CONCLUSION: Home quarantine has aggravated the condition of GDM pregnant women and brought more adverse pregnancy outcomes during the COVID-19 outbreak. Therefore, we suggested governments and hospitals strengthen lifestyle guidance, glucose management, and antenatal care for patients with GDM with home quarantine during public health emergencies.
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COVID-19 , Diabetes Gestacional , Recién Nacido , Embarazo , Humanos , Femenino , Diabetes Gestacional/epidemiología , Resultado del Embarazo/epidemiología , Cesárea , Estudios Retrospectivos , Cuarentena , COVID-19/epidemiología , COVID-19/prevención & control , Macrosomía Fetal/epidemiologíaRESUMEN
Placentation is a major determinant of the success of pregnancy. It is regulated by several factors such as cell adhesion molecules, tight junctions, and gap junctions. The cell adhesion molecules are integrins, cadherins, immunoglobulins, nectins, and selectins. The tight junctions are composed of claudins, occludin, and junction adhesion molecule proteins while the gap junctions are composed of connexins of varying molecular weights. During placentation, some of these molecules regulate trophoblast proliferation, trophoblast fusion, trophoblast migration, trophoblast invasion, trophoblast-endothelium adhesion, glandular remodeling, and spiral artery remodeling. There is a dysregulated placental expression of some of these molecules during obstetric complications. We have, hereby, indicated the expression patterns of the subunits of each of these molecules in the various trophoblast subtypes and in the decidua, and have highlighted their involvement in physiological and pathological placentation. The available evidence points to the relevance of these molecules as distinguishing markers of the various trophoblast lineages and as potential therapeutic targets in the management of malplacentation-mediated diseases.
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Moléculas de Adhesión Celular/metabolismo , Uniones Comunicantes/metabolismo , Enfermedades Placentarias/metabolismo , Placenta/metabolismo , Placentación , Uniones Estrechas/metabolismo , Adhesión Celular , Movimiento Celular , Proliferación Celular , Femenino , Uniones Comunicantes/patología , Humanos , Placenta/patología , Enfermedades Placentarias/patología , Embarazo , Transducción de Señal , Uniones Estrechas/patologíaRESUMEN
INTRODUCTION: Trophoblast development is a crucial event in placentation and pregnancy complications but its underlying mechanisms remain unclear. Thus, we aimed at investigating the role of DiO2 in trophoblast cell line decisions and assessing its placental villous expression in early recurrent miscarriage (ERM) patients. METHODS: The placental villous expression of DiO2 was determined with immunofluorescence. Cell proliferation was measured with the CCK8 kit while cell-cycle and apoptosis were studied with flow-cytometry. Cell migration and invasion were measured with wound-healing and transwell assays, respectively. Gene expression was then assessed with RT-qPCR and western blotting. RESULTS: DiO2 is expressed in the CTB, PCT, DCT and STB of the placenta. Its overexpression arrested trophoblast cell line proliferation at the G1 phase of the cell-cycle by downregulating cyclin-D1 and PCNA, while promoting apoptosis via increased caspase-3 activity and inhibition of the AKT and ERK1/2 signaling pathways. Also, it augmented trophoblast cell line migration and invasion via the upregulation of N-cadherin, vimentin, fascin-1, twist-1 and other epithelial-mesenchymal transition genes. DiO2 knockdown elicited the opposite effects. Surprisingly, each of these effects of DiO2 manipulation was not mediated by thyroid hormone metabolism. Assessment of the ERM placental villi revealed a downregulation of DiO2, N-cadherin, vimentin, fascin-1 and twist-1. The expression of E-cadherin remained unchanged in these placentae. DISCUSSION: During placentation, DiO2 may inhibit trophoblast proliferation while facilitating their differentiation into an invasive phenotype; and that its downregulation may contribute to the shallow trophoblast invasion that precedes ERM. Hence, DiO2 is a potential therapeutic target against ERM.
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Aborto Habitual/enzimología , Yoduro Peroxidasa/metabolismo , Trofoblastos/enzimología , Aborto Habitual/etiología , Apoptosis , Estudios de Casos y Controles , Caspasa 3/metabolismo , Ciclo Celular , Línea Celular , Movimiento Celular , Femenino , Regulación del Desarrollo de la Expresión Génica , Humanos , Embarazo , Yodotironina Deyodinasa Tipo IIRESUMEN
Preeclampsia is a pregnancy complication which threatens the survival of mothers and fetuses. It originates from abnormal placentation, especially insufficient fusion of the cytotrophoblast cells to form the syncytiotrophoblast. In this study, we found that THBS1, a matricellular protein that mediates cell-to-cell and cell-to-matrix interactions, is downregulated during the fusion of primary cytotrophoblast and BeWo cells, but upregulated in the placenta of pregnancies complicated by preeclampsia. Also, THBS1 was observed to interact with CD36, a membrane signal receptor and activator of the cAMP signaling pathway, to regulate the fusion of cytotrophoblast cells. Overexpression of THBS1 inhibited the cAMP signaling pathway and reduced the BeWo cells fusion ratio, while the effects of THBS1 were abolished by a CD36-blocking antibody. Our results suggest that THBS1 signals through a CD36-mediated cAMP pathway to regulate syncytialization of the cytotrophoblast cells, and that its upregulation impairs placental formation to cause preeclampsia. Thus, THBS1 can serve as a therapeutic target regarding the mitigation of abnormal syncytialization and preeclampsia.
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This cohort study assesses the association of maternal hepatitis B virus (HBV) serostatus with pregnancy outcomes in women undergoing freeze-thaw embryo transfer (FET).
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Hepatitis B , Resultado del Embarazo , Embarazo , Femenino , Humanos , Virus de la Hepatitis B , Transferencia de Embrión , Índice de EmbarazoRESUMEN
The paper studied the variation of algal activity during the electrochemical inactivation and the influence factors by the use of TTC-dehydrogenase activity and neutral red staining assays. The treatment reactor was consisted of Ti/RuO2 rod as anode and stainless steel pipe as cathode. The results showed that algal inactivation rate was 45% in cell density after 30 min treatment at 8 mA/cm2. Whereas the decrease of TTC-dehydrogenase activity was 94% and neutral red staining percentage was 100%. The algae after treatment was unable to regrow and it revealed that the algal activity assays can reflect the inactivation effect more correctly than cell density. The electrolytes could influence the inactivation efficiency. The electrolytes of Na2SO4 and NaNO3 had similar effects on algal inactivation and Na2SO4 concentration had small influence on the treatment. However, when the electrolyte contained 0.1 mmol/L NaCl, the algal inactivation was improved obviously with the 87% for TTC-dehydrogenase activity decrease and 82% for neutral red staining ratio. The initial algal concentration also influenced the treatment efficiency. If cell density increased, the inactivation efficiency decreased significantly. All algal cells in samples with cell density of 4.4 x 10(7) cells/L were completely inactivated by the use of natural water as electrolyte within 1 minute.