Experimental data concerning the bioavailability of the different Mg-salts in human organism is inconsistent. Mg-absorption reported by clinical studies largely varies depending on the method used for evaluation. The aim of this study was to evaluate the bioavailability and accessibility of magnesium bound in different Mg-salt compounds, using an in vitro model of intestinal cell barrier. The study included a variety of inorganic (oxide, sulphate, chloride, carbonate) and organic salts (lactate, citrate, pidolate). Caco-2 cells were cultivated in a complete culture medium with different magnesium salts treatments in ascending concentrations. The viability and quantity of cells was analysed by FACS. Mg-absorption was analysed by a direct colorimetric assay, measured by spectrometry. T-test identified a significant decrease in cell count treatment with mg-lactate compared with citrate. Mg-pidolate showed a significantly higher cell viability compared with Mg-citrate, Mg-lactate and Mg-chloride. Even though the difference was not significant, we showed that an increase in Mg2+ salt concentration progressively decreased the cell count and the viability and the effect was universal for all the used Mg-salt treatments. Mg-citrate, chloride, and sulphate showed a significantly lower absorption compared to Mg-carbonate, pidolate and oxide. Our in vitro monolayer model of human intestinal transport showed that viability and quantity of cell decreased with increasing Mg-concentration. We admit that our experiment model may have some limitations in accurately describing an in vivo Mg2+ absorption. Moreover, it is also necessary to assess the relevance of our data in vivo and especially in clinical practice., Ján Kyselovič, Nikola Chomaničová, Adriana Adamičková, Simona Valášková, Barbara Šalingová, Andrea Gažová., and Obsahuje bibliografii
We assessed the concentration of calcium, magnesium and creatinine in 2715 samples of the first morning urine. The investigation comprised the following age groups: children one, two, four, six, ten and thirteen years old, and groups of adults aged 18-35, 36-49, 50-65, 66-75, 76-85 and 86-93 years. The choice was made by random selection of participants of both sexes from diverse regions of the Czech Republic. We found the age to have a marked influence on the value of calcium, magnesium and creatinine, including urinary concentration ratios of calcium/creatinine and magnesium/crcatinine. The urinary calcium concentration was low both in the early and advanced age groups, while it reached peak values in subjects 18-35 years old. The urinary magnesium concentration was also age-dependent, with a maximum in children aged 4 years, and a subsequent decline with advancing age. The value of the ratio urinary calcium/creatinine and urinary magnesium/creatinine was highest in the youngest age group (1-4 years).
There is a growing interest for the beneficial effect of magnesium (Mg) in cardiovascular disorders. A number of cardiovascular disorders including myocardial infarction, arrhythmias and congestive heart failure have been associated with low extracellular or intracellular concentrations of Mg. The efficiency of the preconditioning effect of Mg on cardiac function and infarct size in the globally ischemic-reperfused isolated rat heart was studied together with the role of ATP-sensitive potassium (KATP) channels in protection induced by Mg. Rat hearts were Langendorff perfused, subjected to 30 min of global ischemia and 90 min of reperfusion, including treatment groups which focused on different times of Mg (8 mmol/l) use. Infarct size was measured by triphenyltetrazolium chloride (TTC) method. The left ventricular function was assessed by left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). The administration of Mg before ischemia had an anti-infarct effect in rat hearts and improved cardiac function. The protective effects of magnesium was abolished by the blocking of KATP channels and suggests that K-ATP channel has an important role in the heart protection effect of Mg as a preconditioning agent., M. Bazargan, M. Faghihi, M. Chitsaz., and Obsahuje bibliografii a bibliografické odkazy
Rock dwelling organisms (lithobionts) such as cyanobacteria (prokaryotes) and chlorolichens (eukaryotes) abound in the Negev Desert, where they cover almost all calcareous bedrocks and rock particles (cobbles, boulders). In a small limestone watershed in the Negev Highlands, cyanobacteria inhabit the south-facing (SF) bedrocks, epilithic lichens (accompanied by endolithic lichens) inhabit the north-facing (NF) bedrocks, while endolithic lichens cover most of the cobbles and boulders in both aspects. In order to study their contribution to runoff water, a pair of runoff plots was established on habitats with cyanobacteria, endolithic lichens, and epilithic lichens. Rain and runoff were collected during the hydrological year 2006/07, and the chemical composition (Ca, Mg, Na, K, Cl, SO4, HCO3, Si) of the rain and runoff water was analyzed. Several patterns were observed: (a) as indicated by Si, more dust accumulated on the bedrocks; (b) all substrates exhibited high amounts of Ca, and HCO3; (c) while SF-bedrocks showed enrichment in K, both bedrocks (and especially the NF bedrocks), as well as the NF boulders showed an enrichment in Mg. While the enrichment in Ca and HCO3 can be explained by the contribution of the limestone parent material, the enrichment in K and Mg can be explained by the contribution of the living lithobionts, with K being mainly contributed by the cyanobacteria and Mg mainly by the epilithic lichens. Ion enrichment may therefore be aspect-dependent, reflecting the lithobiont distribution within the drainage basin, partially explaining the enrichment in K and Mg previously recorded in runoff water from the Negev.
Al3+ significantly delayed the loss of chlorophyll (Chl), protein, and carotenoids when compared to K+ and Mg2+ during dark-induced senescence of detached primary leaves of Triticum aestivum. Thylakoid membranes isolated from Al3+ - treated leaves showed a better retention of photosystem (PS) 2, PS1, and whole chain electron transport activities than thylakoids of K+- or Mg2+-treated leaves. These ions protected the electron transport activities and restored the DCMU-dependent fluorescence increase of thylakoid membranes in a valency-dependent manner. Al3+ also delayed the change of excitation energy distribution during senescence. and D. Subhan, S. D. S. Murthy.
The protective role of nutrition factors such as calcium, vitamin D and vitamin K for the integrity of the skeleton is well understood. In addition, integrity of the skeleton is positively influenced by certain trace elements (e.g. zinc, copper, manganese, magnesium, iron, selenium, boron and fluoride) and negatively by others (lead, cadmium, cobalt). Deficiency or excess of these elements influence bone mass and bone quality in adulthood as well as in childhood and adolescence. However, some protective elements may become toxic under certain condition s, depending on dosage (serum concentration), duration of treatment and interactions among individual elements. We review the beneficial and toxic effects of key elements on bone homeostasis., I. Zofkova, M. Davis, J. Blahos., and Obsahuje bibliografii