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Seo, Heewon,Choi, Yohan,Shim, Jangsoo,Yoo, Inkyu,Ka, Hakhyun Society for the Study of Reproduction [etc.] 2014 BIOLOGY OF REPRODUCTION Vol.90 No.5
<P>Prostaglandins (PGs) are involved in many reproductive activities including luteolysis, maternal recognition of pregnancy, endometrial gene expression, conceptus development, and parturition in domestic animals. However, mechanisms by which PGE2 and PGF2alpha are modulated in the uterine endometrium and expression of ABCC4 and SLCO2A1, responsible for efficient transport of PGs across the cell membrane, in the endometrium during the estrous cycle and pregnancy are not fully understood in pigs. Therefore, we determined expression of ABCC4 and SLCO2A1, genes involved in transport of PGE2 and PGF2alpha in the uterine endometrium during the estrous cycle and pregnancy in pigs. ABCC4 and SLCO2A1 mRNAs were expressed in the uterine endometrium, most abundantly on Day 12 of pregnancy and during late pregnancy. Expression of ABCC4 mRNA and protein was localized mainly to uterine luminal epithelial (LE) and glandular epithelial (GE) cells, and expression of SLCO2A1 mRNA and protein was expressed primarily in uterine LE and blood vessels. Expression of ABCC4 and SLCO2A1 mRNAs was also detected in conceptuses during early pregnancy. In addition, explant culture experiments showed that increasing doses of interleukin 1B (IL1B) with estrogen and progesterone increased levels of ABCC4 and SLCO2A1 mRNAs in the uterine endometrium. These results indicate that expression of genes responsible for transport of PGE2 and PGF2alpha are dynamically regulated in the uterine endometrium during pregnancy and that ABCC4 and SLCO2A1 play critical roles in supporting the establishment and maintenance of pregnancy by regulating PG transport at the maternal-fetal interface in pigs.</P>
Seo, Heewon,Choi, Yohan,Shim, Jangsoo,Yoo, Inkyu,Ka, Hakhyun Society for the Study of Reproduction [etc.] 2014 BIOLOGY OF REPRODUCTION Vol.90 No.5
<P>Prostaglandins (PGs) are important lipid mediators regulating various reproductive processes in many species. In pigs, the expression pattern of PGE2 and PGF2α metabolic enzymes and the regulatory mechanism controlling PGE2 and PGF2α levels in the uterus during pregnancy are not completely understood. This study determined endometrial expression of the genes (PLA2G4A, PTGS1, PTGS2, PTGES, PTGES2, PTGES3, AKR1B1, CBR1, and HPGD) involved in PGE2 and PGF2α metabolism during the estrous cycle and pregnancy and measured levels of PGE2 and PGF2α in uterine endometrial tissues and uterine flushings at the time of conceptus implantation in pigs. Except PTGES3, expression of the genes studied changed in a pregnancy-stage-specific manner, and localization of PTGES, AKR1B1, CBR1, and HPGD mRNAs were cell-type specific in the uterine endometrium. Levels of both PGE2 and PGF2α in uterine endometrial tissues and uterine lumen were higher on Day 12 of pregnancy than those of the estrous cycle and affected by different morphology of spherical and filamentous conceptuses. Furthermore, we determined that endometrial expression of AKR1B1, known to encode a PGF2α synthase in other species, was increased by estrogen and interleukin-1beta and that AKR1B1 exhibited PGF2α synthase activity in the porcine uterine endometrium. These results in pigs indicate that the PGE2 and PGF2α metabolic enzymes are expressed stage specifically in the endometrium during pregnancy and regulate the abundance of PGE2 and PGF2α in the uterus at the time of implantation and that AKR1B1 may act as a major PGF synthase in the endometrium during early pregnancy.</P>
Timeliness-aware Anti-discrimination MAC Scheme for Wireless Passive Sensor Networks
Heewon Seo,Jin Kyung Park,Cheon Won Choi 대한전자공학회 2020 IEIE Transactions on Smart Processing & Computing Vol.9 No.2
In a wireless passive sensor network, radio frequency (RF) sources wirelessly supply energy to sensor nodes. Against theoretical expectations of an abundance of energy, a wireless passive sensor network suffers from a scarcity of energy in practice. Such a scarcity compels the network to adopt a contending-type medium access control (MAC) scheme, which inevitably brings about a packet collision, and hence a capture phenomenon. The problem is that the packet collision may incur an intolerable delay in packet delivery, and furthermore, the capture phenomenon can cause discrimination in packet delivery against sensor nodes that are far from the sink node. In this paper, we thus confine our attention to a class of contending-type MAC schemes, rooted in framed and slotted ALOHA, which guarantee a degree of timeliness in packet delivery. In the timeliness-aware class, we then seek an anti-discrimination MAC scheme that prevents discrimination against distant sensor nodes by providing every sensor node with an equal opportunity to succeed in packet delivery, i.e., in the substantive sense of equality. In case studies, we construct an antidiscrimination MAC scheme in an explicit form. Also, we develop an exact expression of nodal throughput that can be attained by an anti-discrimination MAC scheme. Using the throughput formula, we then find an optimal anti-discrimination MAC scheme that attains maximum total throughput among all the anti-discrimination MAC schemes. Numerical examples corroborate that an optimal anti-discrimination MAC scheme not only always achieves stronger nodal evenness in throughput but also occasionally attains higher total throughput than a conventional MAC scheme.
Heewon Seo,Jin Kyung Park,Cheon Won Choi 대한전자공학회 2021 IEIE Transactions on Smart Processing & Computing Vol.10 No.4
A wireless passive sensor network is distinguished from ordinary wireless sensor networks by radio frequency (RF) sources that radiate RF waves and supply energy to sensor nodes. Against theoretical expectations, such a network suffers from a scarcity of energy, which compels to employ a contending-type medium access control (MAC) scheme. Consequently, a collision may take place among the packets sent by some sensor nodes. Also, the interference power brought by the colliding packets may hinder a sink node from identifying any packet. Apparently, the interference power highly influences the performance of a wireless passive sensor network. Thus, it is essential to appropriately describe the interference power to evaluate the performance. In this paper, we characterize the interference power, occurring in a wireless passive sensor network, as a sum of random variables governed by log-normal distributions, which are mutually independent but are not necessarily identical. Then, we prove the asymptotic normality of the interference power and, in pursuit of tractability rather than accuracy, we propose a normal approximation to the interference power brought by a finite number of sensor nodes. To investigate the accuracy of the proposed normal approximation, we take the Kolmogorov-Smirnov distance and present an exact expression of the Berry-Esséen bound associated with the interference power. Also, to explore the acceptability of the normal approximation, we employ three well-known statistical tests for normality. Comparative studies of Berry-Esséen bounds reveal that the normal approximation to the interference power is moderately accurate. Furthermore, hypothesis testing for normality shows that the normal approximation is acceptable even in the case that the interference power is incurred by a relatively small number of packets (or, equivalently, sensor nodes) in a wireless passive sensor network.