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Calcium Transport (calcium + transport)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

ENDOCRINE REGULATION OF CALCIUM TRANSPORT IN EPITHELIA

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2008
Ramesh C Khanal
SUMMARY 1Calcium (re)absorption occurs in epithelia, including the intestine, kidney, mammary glands, placenta and gills (in the case of fish). 2Calcium is transported across epithelia by two transport mechanisms, paracellular and transcellular, and the movement is regulated by a complex array of transport processes that are mediated by hormonal, developmental and physiological factors involving the gastrointestinal tract, bone, kidney and the parathyroids. 3Clear understanding of the calcium transport pathways and their endocrine regulation is critical for minimizing various metabolic and health disorders at different physiological stages. Here, we first briefly review the calcium transport mechanisms before discussing in detail the endocrine factors that regulate calcium transport in the epithelia. [source]

Calcium Channel TRPV6 Is Involved in Murine Maternal,Fetal Calcium Transport,,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2008
Yoshiro Suzuki
Abstract Maternal,fetal calcium (Ca2+) transport is crucial for fetal Ca2+ homeostasis and bone mineralization. In this study, the physiological significance of the transient receptor potential, vanilloid 6 (TRPV6) Ca2+ channel in maternal,fetal Ca2+ transport was investigated using Trpv6 knockout mice. The Ca2+ concentration in fetal blood and amniotic fluid was significantly lower in Trpv6 knockout fetuses than in wildtypes. The transport activity of radioactive Ca2+ (45Ca) from mother to fetuses was 40% lower in Trpv6 knockout fetuses than in wildtypes. The ash weight was also lower in Trpv6 knockout fetuses compared with wildtype fetuses. TRPV6 mRNA and protein were mainly localized in intraplacental yolk sac and the visceral layer of extraplacental yolk sac, which are thought to be the places for maternal,fetal Ca2+ transport in mice. These expression sites were co-localized with calbindin D9K in the yolk sac. In wildtype mice, placental TRPV6 mRNA increased 14-fold during the last 4 days of gestation, which coincides with fetal bone mineralization. These results provide the first in vivo evidence that TRPV6 is involved in maternal,fetal Ca2+ transport. We propose that TRPV6 functions as a Ca2+ entry pathway, which is critical for fetal Ca2+ homeostasis. [source]

Changes in calcium absorption and subsequent tissue distribution induced by Maillard reaction products: in vitro and in vivo assays,

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2006
Cristina Delgado-Andrade
Abstract The effects of Maillard reaction products (MRP) from glucose,lysine and glucose,methionine on calcium bioavailability were studied by in vivo (rats) and in vitro (Caco-2 cells) assays. Equimolar glucose/lysine and glucose/methionine mixtures (40% moisture) were heated (150 °C, 30 min) to prepare samples (GL30 and GM30, respectively). For 21 days, rats were fed a control diet (control group) or diets containing separately 3% of the heated mixtures (GL30 and GM30 groups, respectively). In the last week a calcium balance was performed, after which the animals were sacrificed and some organs and serum were removed to analyze calcium levels. A second balance was carried out throughout the experimental period to calculate global calcium retention (retained calcium during the entire 21 days). Unheated and heated samples were used for calcium transport experiments in Caco-2 cells. Food intake and final body weight were lower in the GM30 group. Calcium fecal excretion decreased and digestibility increased in this group. Accordingly, increased calcium transport in Caco-2 cells was found in the presence of the GM30 sample, when compared with the unheated sample. However, global calcium retention tended to decrease in the GM30 group, mainly owing to the lower food intake. Bone calcium concentrations decreased in the animals fed the MRP diets. The possible long-term effects of MRP intake on calcium digestibility and bone calcium should be taken into account to avoid related diseases. Copyright © 2005 Society of Chemical Industry [source]

cDNA-AFLP reveals genes differentially expressed during the hypersensitive response of cassava

MOLECULAR PLANT PATHOLOGY, Issue 2 2005
BENJAMIN P. KEMP
SUMMARY The tropical staple cassava is subject to several major diseases, such as cassava bacterial blight, caused by Xanthomonas axonopodis pv. manihotis. Disease-resistant genotypes afford the only practical solution, yet despite the global importance of this crop, little is known about its defence mechanisms. cDNA-AFLP was used to isolate cassava genes differentially expressed during the hypersensitive reaction (HR) of leaves in response to an incompatible Pseudomonas syringae pathovar. Seventy-eight transcript-derived fragments (TDFs) showing differential expression (c. 75% up-regulated, 25% down-regulated) were identified. Many encoded putative homologues of known defence-related genes involved in signalling (e.g. calcium transport and binding, ACC oxidases and a WRKY transcription factor), cell wall strengthening (e.g. cinnamoyl coenzyme A reductase and peroxidase), programmed cell death (e.g. proteases, 26S proteosome), antimicrobial activity (e.g. proteases and ,-1,3-glucanases) and the production of antimicrobial compounds (e.g. DAHP synthase and cytochrome P450s). Full-length cDNAs including a probable matrix metalloprotease and a WRKY transcription factor were isolated from six TDFs. RT-PCR or Northern blot analysis showed HR-induced TDFs were maximally expressed at 24 h, although some were produced by 6 h; some were induced, albeit more slowly, in response to wounding. This work begins to reveal potential defence-related genes of this understudied, major crop. [source]