Placentation apical

Although a uniform nomenclature for Na /H exchanger isoforms has not yet been adopted, we will refer to the amiloride-sensitive type of Na" /H exchanger that is present in the basolateral membrane of epithelia (apical membrane of placental syncytiotrophoblast) and also widely distributed in non-epithelial cells as the sensitive-type. The relatively amiloride-resistant isoform present in apical mem-... 

Breast Cancer Resistance Protein (BCRP, also known as MXR or ABCP), first cloned from mitoxantrone and anthracycline-resistant breast and colon cancer cells [188, 189] is a half-transporter efflux pump believed to function as a homo-or hetero-dimer. Following its identification, BCRP-mediated drug resistance was observed for topoisomerase inhibitors including camptothecins [190, 191] and in-dolocarbazoles [192]. In normal tissues, BCRP was detected in placental syncytio-trophoblasts, hepatocyte canalicular membrane, apical intestinal epithelia and vascular endothelial cells [193]. These findings support the important role BCRP plays in modulating topotecan bioavailability, fetal exposure and hepatic elimination [194]. Considering that the substrates and tissue distributions for BCRP overlap somewhat with MDR1 and MRPs [195], additional studies will be required to define the relative contribution of each of these transporters in the overall and tis-... 

Morphologically, this is demonstrated by the development of a multinuclear syncytium with apical microvilli [49], while functional differentiation is associated with induction and synthesis of hormones, such as human chorionic gonadotropin (hCG) and human placental lactogen (hPL) [50, 51]. Cultures of primary cytotrophoblasts have been used to study functional expression of P-gp, amino acid uptake, and hormonal stimulation of amino acid uptake and... 

Either Transwell inserts or side-by-side diffusion chambers can be used for transport studies. Bode et al. have provided an excellent review on this subject [60], Briefly, cells are incubated for 30-60 min with a buffer solution. To initiate the transport study, a transport buffer containing the drug under investigation is added to either the apical or the basal chamber depending on the transport direction of interest. At predetermined time points, the respective receiver chamber is sampled and the withdrawn volume is replaced with the same volume of fresh buffer. The permeability coefficient (Papp) is calculated and the ratio of /apP in the basolateral-to-apical direction versus that in the apical-to-basolateral direction gives the efflux ratio. These sort of transport experiments are well suited to determine if drugs/xenobiotics are substrates of the placental efflux proteins. 

Leaves usually large placentation usually axile or apical or basal stamens mostly numerous. 

Pepper lovers know well what chemists have now demonstrated, namely that capsaicinoids are accumulated in the inner placental part of peppers and especially in their basal and apical sections. Therefore, pungency can be moderate by removing the irmer part of the pod, which contains the placenta, and cutting away its tip and... 

Implantation and subsequent placentation is a unique mammalian form of reproduction. A fertilized mammalian egg autonomously develops into a blastocyst, which must be successfully implanted in the uterus to develop further into a fetus. Initial adhesion of the embryo to the uterus occurs via the apical cell membrane of two polarized epithelial cells, the trophoblast of blastocysts, and surface epithehal cells of the endometrium. This adhesion is unique because it is apical-apical adhesion between two epithelial cells, whereas generally apical cell surfaces of epithelia are nonadhesive. 

Folate (vitamin Bg) is a low-molecular-weight (441 Da) compound essential in cell proliferation and for the biosynthesis of methionine, serine, deoxythymine add, and purine. Folate is internalized via two independent pathways either by transport of folate by the folate reeeptor or as 5-methyl-tetrahydrofolate by the reduced folate carrier. The expression of folate receptor (FR) in healthy tissue is limited to activated macrophages, placental cells, and the apical surface of polarized epithelia, where it is present in different isoforms [56]. The overexpression of FR on a broad range of solid tumors (ovary, lung, breast, kidney, brain, endometrium, and colon) makes it a suitable target for selective tumor drug delivery (for review, see [57J). 

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