Oral calcium carbonate affects calcium but not phosphorus balance in stage 3-4 chronic kidney disease.

PubMed

Hill, Kathleen M; Martin, Berdine R; Wastney, Meryl E; McCabe, George P; Moe, Sharon M; Weaver, Connie M; Peacock, Munro

2013-05-01

Patients with chronic kidney disease (CKD) are given calcium carbonate to bind dietary phosphorus, reduce phosphorus retention, and prevent negative calcium balance; however, data are limited on calcium and phosphorus balance during CKD to support this. Here, we studied eight patients with stage 3 or 4 CKD (mean estimated glomerular filtration rate 36 ml/min) who received a controlled diet with or without a calcium carbonate supplement (1500 mg/day calcium) during two 3-week balance periods in a randomized placebo-controlled cross-over design. All feces and urine were collected during weeks 2 and 3 of each balance period and fasting blood, and urine was collected at baseline and at the end of each week. Calcium kinetics were determined using oral and intravenous (45)calcium. Patients were found to be in neutral calcium and phosphorus balance while on the placebo. Calcium carbonate supplementation produced positive calcium balance, did not affect phosphorus balance, and produced only a modest reduction in urine phosphorus excretion compared with placebo. Calcium kinetics demonstrated positive net bone balance but less than overall calcium balance, suggesting soft-tissue deposition. Fasting blood and urine biochemistries of calcium and phosphate homeostasis were unaffected by calcium carbonate. Thus, the positive calcium balance produced by calcium carbonate treatment within 3 weeks cautions against its use as a phosphate binder in patients with stage 3 or 4 CKD, if these findings can be extrapolated to long-term therapy.

Genetically Encoded Calcium Indicators For Studying Long-Term Calcium Dynamics During Apoptosis

PubMed Central

Garcia, M. Iveth; Chen, Jessica J.; Boehning, Darren

2017-01-01

Intracellular calcium release is essential for regulating almost all cellular functions. Specific spatio-temporal patterns of cytosolic calcium elevations are critical determinants of cell fate in response to pro-apoptotic cellular stressors. As the apoptotic program can take hours or days, measurement of long-term calcium dynamics are essential for understanding the mechanistic role of calcium in apoptotic cell death. Due to the technical limitations of using calcium-sensitive dyes to measure cytosolic calcium little is known about long-term calcium dynamics in living cells after treatment with apoptosis-inducing drugs. Genetically encoded calcium indicators could potentially overcome some of the limitations of calcium-sensitive dyes. Here, we compared the performance of the genetically encoded calcium indicators GCaMP6s and GCaMP6f with the ratiometric dye Fura-2. GCaMP6s performed as well or better than Fura-2 in detecting agonist-induced calcium transients. We then examined the utility of GCaMP6s for continuously measuring apoptotic calcium release over the course of ten hours after treatment with staurosporine. We found that GCaMP6s was suitable for measuring apoptotic calcium release over long time courses and revealed significant heterogeneity in calcium release dynamics in individual cells challenged with staurosporine. Our results suggest GCaMP6s is an excellent indicator for monitoring long-term changes cytosolic calcium during apoptosis. PMID:28073595

Reduction of calcium flux from the extracellular region and endoplasmic reticulum by amorphous nano-silica particles owing to carboxy group addition on their surface.

PubMed

Onodera, Akira; Yayama, Katsutoshi; Morosawa, Hideto; Ishii, Yukina; Tsutsumi, Yasuo; Kawai, Yuichi

2017-03-01

Several studies have reported that amorphous nano-silica particles (nano-SPs) modulate calcium flux, although the mechanism remains incompletely understood. We thus analyzed the relationship between calcium flux and particle surface properties and determined the calcium flux route. Treatment of Balb/c 3T3 fibroblasts with nano-SPs with a diameter of 70 nm (nSP70) increased cytosolic calcium concentration, but that with SPs with a diameter of 300 or 1000 nm did not. Surface modification of nSP70 with a carboxy group also did not modulate calcium flux. Pretreatment with a general calcium entry blocker almost completely suppressed calcium flux by nSP70. Preconditioning by emptying the endoplasmic reticulum (ER) calcium stores slightly suppressed calcium flux by nSP70. These results indicate that nSP70 mainly modulates calcium flux across plasma membrane calcium channels, with subsequent activation of the ER calcium pump, and that the potential of calcium flux by nano-SPs is determined by the particle surface charge.

Calcium-regulated in vivo protein phosphorylation in Zea mays L. root tips

NASA Technical Reports Server (NTRS)

Raghothama, K. G.; Reddy, A. S.; Friedmann, M.; Poovaiah, B. W.

1987-01-01

Calcium dependent protein phosphorylation was studied in corn (Zea mays L.) root tips. Prior to in vivo protein phosphorylation experiments, the effect of calcium, ethyleneglycol-bis-(beta-aminoethyl ether)-N-N' -tetraacetic acid (EGTA) and calcium ionophore (A-23187) on phosphorus uptake was studied. Calcium increased phosphorus uptake, whereas EGTA and A-23187 decreased it. Consequently, phosphorus concentration in the media was adjusted so as to attain similar uptake in different treatments. Phosphoproteins were analyzed by two-dimensional gel electrophoresis. Distinct changes in phosphorylation were observed following altered calcium levels. Calcium depletion in root tips with EGTA and A-23187 decreased protein phosphorylation. However, replenishment of calcium following EGTA and ionophore pretreatment enhanced phosphorylation of proteins. Preloading of the root tips with 32P in the presence of EGTA and A-23187 followed by a ten minute calcium treatment, resulted in increased phosphorylation indicating the involvement of calcium, calcium and calmodulin-dependent kinases. Calmodulin antagonist W-7 was effective in inhibiting calcium-promoted phosphorylation. These studies suggest a physiological role for calcium-dependent phosphorylation in calcium-mediated processes in plants.

Diagnosis and assessment of skeletal related disease using calcium 41

DOEpatents

Hillegonds, Darren J [Oakland, CA; Vogel, John S [San Jose, CA; Fitzgerald, Robert L [Encinitas, CA; Deftos, Leonard J [Del Mar, CA; Herold, David [Del Mar, CA; Burton, Douglas W [San Diego, CA

2012-05-15

A method of determining calcium metabolism in a patient comprises the steps of administering radioactive calcium isotope .sup.41Ca to the patient, allowing a period of time to elapse sufficient for dissemination and reaction of the radioactive calcium isotope .sup.41Ca by the patient, obtaining a sample of the radioactive calcium isotope .sup.41Ca from the patient, isolating the calcium content of the sample in a form suitable for precise measurement of isotopic calcium concentrations, and measuring the calcium content to determine parameters of calcium metabolism in the patient.

Diagnosis and assessment of skeletal related disease using calcium 41

DOEpatents

Hillegonds, Darren J.; Vogel, John S.; Fitzgerald, Robert L.; Deftos, Leonard J.; Herold, David; Burton, Douglas W.

2013-03-05

A method of determining calcium metabolism in a patient comprises the steps of administering radioactive calcium isotope .sup.41Ca to the patient, allowing a period of time to elapse sufficient for dissemination and reaction of the radioactive calcium isotope .sup.41Ca by the patient, obtaining a sample of the radioactive calcium isotope .sup.41Ca from the patient, isolating the calcium content of the sample in a form suitable for precise measurement of isotopic calcium concentrations, and measuring the calcium content to determine parameters of calcium metabolism in the patient.

Bioaccessibility of four calcium sources in different whey-based dairy matrices assessed by in vitro digestion.

PubMed

Lorieau, Lucie; Le Roux, Linda; Gaucheron, Frédéric; Ligneul, Amandine; Hazart, Etienne; Dupont, Didier; Floury, Juliane

2018-04-15

Numerous calcium sources are available to enrich food, but their behavior during digestion is still unknown. This study focused on the influence of the gastro-intestinal pH, the food structure and the calcium source on the bioaccessibility of the nutrient. Four calcium sources were studied: calcium carbonate, calcium citrate malate, calcium phosphate and calcium bisglycinate. These were added to dairy matrices, containing cream and whey proteins, of different forms (liquid or gel). The kinetics of solubility and ionic calcium concentration during in vitro digestion were studied, as function of gastro-intestinal pH. All calcium sources were almost fully soluble in the gastric compartment, and then became insoluble in the intestinal phase. The level of calcium insolubilisation in the intestinal phase was not significantly influenced by the matrix structure (liquid or gel), but was more dependent on the calcium source, this effect leading to different final calcium bioaccessibility from 36% to 20%. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of habitat geology on calcium intake and calcium status of wild rodents.

PubMed

Shore, R F; Balment, R J; Yalden, D W

1991-12-01

Calcium is essential for normal physiological function, reproduction and growth in mammals but its distribution in the natural environment is heterogeneous. Spatial variation in calcium soil content is especially marked in the Peak District, United Kingdom, where both calcium-rich limestone and calcium-poor gritstone rock types occur. Wood mice Apodemus sylvaticus (L) and bank voles Clethrionomys glareolus (Schreber 1780) from limestone areas had significantly higher calcium concentrations in stomach contents and in faeces compared with their counterparts from gritstone areas. Calcium status was assessed from serum calcium concentration, femur weight, ash content of the body, calcium concentration in the femur and body ash. There was no significant difference in serum calcium concentration, femur calcium concentration and body ash calcium concentration between animals from the limestone and the gritstone. However, on the limestone, bank voles, but not wood mice, had significantly heavier femora and a greater proportion of ash in the body compared with their gritstone counterparts.

Calcium signaling in taste cells: regulation required.

PubMed

Medler, Kathryn F

2010-11-01

Peripheral taste receptor cells depend on distinct calcium signals to generate appropriate cellular responses that relay taste information to the central nervous system. Some taste cells have conventional chemical synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release from stores to formulate an output signal through a hemichannel. Despite the importance of calcium signaling in taste cells, little is known about how these signals are regulated. This review summarizes recent studies that have identified 2 calcium clearance mechanisms expressed in taste cells, including mitochondrial calcium uptake and sodium/calcium exchangers (NCXs). These studies identified a unique constitutive calcium influx that contributes to maintaining appropriate calcium homeostasis in taste cells and the role of the mitochondria and exchangers in this process. The additional role of NCXs in the regulation of evoked calcium responses is also discussed. Clearly, calcium signaling is a dynamic process in taste cells and appears to be more complex than has previously been appreciated.

Vitamin D Supplementation in Submariners

DTIC Science & Technology

2008-12-02

prevalence of over 10% in men.71 Most stones are composed of calcium oxalate or calcium phosphate.72 It is the composition of these stones that...urine that combine with calcium to form calcium oxalate stones.77 One of the major factors that reduce hyperoxaluria is calcium in the diet. The... calcium in the intestinal lumen forms insoluble calcium salts with the oxalates and is not absorbed. A diet low in calcium will allow more oxalates to be

Magnesium supplementation through seaweed calcium extract rather than synthetic magnesium oxide improves femur bone mineral density and strength in ovariectomized rats.

PubMed

Bae, Yun Jung; Bu, So Young; Kim, Jae Young; Yeon, Jee-Young; Sohn, Eun-Wha; Jang, Ki-Hyo; Lee, Jae-Cheol; Kim, Mi-Hyun

2011-12-01

Commercially available seaweed calcium extract can supply high amounts of calcium as well as significant amounts of magnesium and other microminerals. The purpose of this study was to investigate the degree to which the high levels of magnesium in seaweed calcium extract affects the calcium balance and the bone status in ovariectomized rats in comparison to rats supplemented with calcium carbonate and magnesium oxide. A total of 40 Sprague-Dawley female rats (7 weeks) were divided into four groups and bred for 12 weeks: sham-operated group (Sham), ovariectomized group (OVX), ovariectomized with inorganic calcium and magnesium supplementation group (OVX-Mg), and ovariectomized with seaweed calcium and magnesium supplementation group (OVX-SCa). All experimental diets contained 0.5% calcium. The magnesium content in the experimental diet was 0.05% of the diet in the Sham and OVX groups and 0.1% of the diet in the OVX-Mg and OVX-SCa groups. In the calcium balance study, the OVX-Mg and OVX-SCa groups were not significantly different in calcium absorption compared to the OVX group. However, the femoral bone mineral density and strength of the OVX-SCa group were higher than those of the OVX-Mg and OVX groups. Seaweed calcium with magnesium supplementation or magnesium supplementation alone did not affect the serum ALP and CTx levels in ovariectomized rats. In summary, consumption of seaweed calcium extract or inorganic calcium carbonate with magnesium oxide demonstrated the same degree of intestinal calcium absorption, but only the consumption of seaweed calcium extract resulted in increased femoral bone mineral density and strength in ovariectomized rats. Our results suggest that seaweed calcium extract is an effective calcium and magnesium source for improving bone health compared to synthetic calcium and magnesium supplementation.

The effect of variable calcium and very low calcium diets on human calcium metabolism. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Chu, J.

1971-01-01

The effects of a very low calcium diet, with variable high and low protein intake, on the dynamics of calcium metabolism and the mechanism of calciuretics, are examined. The experiment, using male subjects, was designed to study the role of intestinal calcium absorption on urinary calcium excretion, and the rate of production of endogeneously secreted calcium in the gastrointestinal tract. The study showed an average of 70% fractional absorption rate during very low calcium intake, and that a decrease in renal tubular reabsorption of calcium is responsible for calciuretic effects of high protein intake. The study also indicates that there is a tendency to develop osteoporosis after long periods of low calcium intake, especially with a concurrent high protein intake.

Is ionized calcium a reliable predictor of hypocalcemia after total thyroidectomy? A before and after study

PubMed Central

TARTAGLIA, F.; GIULIANI, A.; SGUEGLIA, M.; PATRIZI, G.; DI ROCCO, G.; BLASI, S.; RUSSO, G.; TORTORELLI, G.; GIANNOTTI, D.; REDLER, A.

2014-01-01

Summary Wanting to find a way of identifying patients suitable for early discharge after thyroidectomy, we set out to establish whether ionized calcium concentration is a better predictor of post-surgical hypocalcemia than total serum calcium. Data were analyzed to establish whether serum ionized calcium concentrations are correlated with total serum calcium levels and symptomatic hypocalcemia after thyroidectomy. Sixty-two patients undergoing total thyroidectomy at the Department of Surgical Sciences of the “Sapienza” University of Rome, Italy, in 2010. Ionized calcium was measured before (day 0) and after surgery (days 1, 2 and 60) in all the patients. These measurements were compared with preoperative (day 0) and postoperative total serum calcium levels (days 1, 2 and 60). The preoperative ionized calcium levels differed from the ionized calcium levels recorded on days 1 and 2; this pattern was not observed for the total calcium concentrations. Conversely, total calcium on days I and II correlated significantly with the various ionized calcium measurements. The presence of parathyroid glands in the surgical specimen did not seem to affect suitability for discharge. The statistical analysis showed that ionized calcium measurements are more reliable than total calcium measurements in the immediate and long-term follow-up of total thyroidectomy patients. Applying a 95% confidence interval we established reference values for both total serum calcium and ionized calcium, below which all patients develop postoperative symptomatic hypocalcemia. In conclusion, measurement of ionized calcium, as opposed to total calcium, should be strongly recommended in the immediate and long-term follow-up of total thyroidectomy patients. PMID:24690338

Consequences of calcium decline on the embryogenesis and life history of Daphnia magna.

PubMed

Giardini, Jamie-Lee; Yan, Norman D; Heyland, Andreas

2015-07-01

Ambient calcium is declining in thousands of soft-water lake habitats in temperate regions as a consequence of unsustainable forestry practices, decreased atmospheric calcium deposition and acidic deposition. As their exoskeleton is heavily reinforced with calcium, freshwater crustaceans have a high specific calcium requirement relative to other aquatic organisms. Daphnia, in particular, is an ideal crustacean for investigating the consequences of calcium decline because it is an abundant and important member of freshwater zooplankton communities. Although it has been established that adult and juvenile Daphnia have different tolerances to low ambient calcium as a result of their different life stage-specific calcium requirements, the consequences of declining calcium on embryonic development have never been investigated. Here, we describe the distribution of calcium in embryonic stages of D. magna and introduce a novel and easy to use staging scheme. We tested whether calcium can be traced from mothers to their offspring. Finally, we assessed the fitness consequences of maternal provisioning in limiting calcium environments. We found that while embryos require calcium for their development and moulting, they do not equilibrate with environmental calcium levels. Instead, we were able to trace calcium from mothers to their offspring. Furthermore, our data strongly suggest that females are faced with an allocation trade-off between providing calcium to their offspring and using it for growth and moulting. Together, these data provide novel insights into the consequences of calcium decline for freshwater zooplankton. © 2015. Published by The Company of Biologists Ltd.

Genetically encoded calcium indicators for studying long-term calcium dynamics during apoptosis.

PubMed

Garcia, M Iveth; Chen, Jessica J; Boehning, Darren

2017-01-01

Intracellular calcium release is essential for regulating almost all cellular functions. Specific spatio-temporal patterns of cytosolic calcium elevations are critical determinants of cell fate in response to pro-apoptotic cellular stressors. As the apoptotic program can take hours or days, measurement of long-term calcium dynamics are essential for understanding the mechanistic role of calcium in apoptotic cell death. Due to the technical limitations of using calcium-sensitive dyes to measure cytosolic calcium little is known about long-term calcium dynamics in living cells after treatment with apoptosis-inducing drugs. Genetically encoded calcium indicators could potentially overcome some of the limitations of calcium-sensitive dyes. Here, we compared the performance of the genetically encoded calcium indicators GCaMP6s and GCaMP6f with the ratiometric dye Fura-2. GCaMP6s performed as well or better than Fura-2 in detecting agonist-induced calcium transients. We then examined the utility of GCaMP6s for continuously measuring apoptotic calcium release over the course of ten hours after treatment with staurosporine. We found that GCaMP6s was suitable for measuring apoptotic calcium release over long time courses and revealed significant heterogeneity in calcium release dynamics in individual cells challenged with staurosporine. Our results suggest GCaMP6s is an excellent indicator for monitoring long-term changes cytosolic calcium during apoptosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Calcium Balance in Chronic Kidney Disease.

PubMed

Hill Gallant, Kathleen M; Spiegel, David M

2017-06-01

The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

Multiparameter imaging of calcium and abscisic acid and high-resolution quantitative calcium measurements using R-GECO1-mTurquoise in Arabidopsis.

PubMed

Waadt, Rainer; Krebs, Melanie; Kudla, Jörg; Schumacher, Karin

2017-10-01

Calcium signals occur in specific spatio-temporal patterns in response to various stimuli and are coordinated with, for example, hormonal signals, for physiological and developmental adaptations. Quantification of calcium together with other signalling molecules is required for correlative analyses and to decipher downstream calcium-decoding mechanisms. Simultaneous in vivo imaging of calcium and abscisic acid has been performed here to investigate the interdependence of the respective signalling processes in Arabidopsis thaliana roots. Advanced ratiometric genetically encoded calcium indicators have been generated and in vivo calcium calibration protocols were established to determine absolute calcium concentration changes in response to auxin and ATP. In roots, abscisic acid induced long-term basal calcium concentration increases, while auxin triggered rapid signals in the elongation zone. The advanced ratiometric calcium indicator R-GECO1-mTurquoise exhibited an increased calcium signal resolution compared to commonly used Förster resonance energy transfer-based indicators. Quantitative calcium measurements in Arabidopsis root tips using R-GECO1-mTurquoise revealed detailed maps of absolute calcium concentration changes in response to auxin and ATP. Calcium calibration protocols using R-GECO1-mTurquoise enabled high-resolution quantitative imaging of resting cytosolic calcium concentrations and their dynamic changes that revealed distinct hormonal and ATP responses in roots. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

A Closer look at calcium absorption and the benefits and risks of dietary versus supplemental calcium.

PubMed

Booth, Anna; Camacho, Pauline

2013-11-01

To perform a thorough search of the literature on calcium research and specifically address the topic of calcium absorption. PubMed and Ovid were the main engines used for primary literature searches; textbooks, review articles, and book chapters are examples of the other sources used for supplemental information. Regarding calcium absorption, it seems apparent that the absorption efficiency of all calcium salts, regardless of solubility, is fairly equivalent and not significantly less than the absorption efficiency of dietary calcium. However, dietary calcium has been shown to have greater impact in bone building than supplemental calcium. This is likely due to improved absorption with meals and the tendency of people to intake smaller amounts more frequently, which is more ideal for the body's method of absorption. In addition, the cardiovascular risks of excessive calcium intake appear to be more closely related to calcium supplements than dietary calcium; this relationship continues to be controversial in the literature. We conclude that further studies are needed for direct comparison of supplemental and dietary calcium to fully establish if one is superior to the other with regard to improving bone density. We also propose further studies on the cardiovascular risk of long-term increased calcium intake and on physician estimates of patients' daily calcium intake to better pinpoint those patients who require calcium supplementation.

Calcium sources for milk production in Holstein cows via changes in dry matter intake, mineral utilization, and mineral source buffering potential.

PubMed

Wohlt, J E; Ritter, D E; Evans, J L

1986-11-01

Three supplemental sources of inorganic calcium (calcite flour, aragonite, albacar), each differing in particle size and rate of reactivity, provided .6 or .9% calcium in corn silage:grain (1:1 dry matter) diets of high producing dairy cows. All cows were fed calcite flour at .6% calcium during the first 4 wk of lactation. On d 29 of lactation 5 cows were assigned to each of the six diets. Peak milk yield paralleled dry matter intake and was higher when calcite flour and aragonite provided .9% calcium, intermediate when all sources provided .6% calcium, and lower when albacar provided .9% calcium. However, adaptations to calcium source and to particle sizes of a calcium source (.35 to 1190 mu) were made within 40 d by lactating Holsteins. Starch increased and pH decreased in feces of cows fed albacar. Increasing calcium in the diet provided more buffering capacity in the gastrointestinal tract. True absorption of calcium did not differ from linearity due to source when fecal calcium was regressed on ingested calcium but did vary as a function of diet percentage. Thus, calcium retention was increased when cows were fed .9 vs. .6% calcium. These data suggest that a slow reacting (coarser) inorganic calcium source should be fed at a higher amount to optimize feed intake and milk production.

The salutary effect of dietary calcium on bone mass in a rat model of simulated weightlessness

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Globus, R.; Halloran, B. P.; Morey-Holton, E.

1985-01-01

Whether supplementation of dietary calcium reduces the differences in bone mass of unweighed limbs and normally weighted limbs, and whether parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D (1,25(OH)2D) respond differently to dietary calcium in unweighted animals in comparison with pair-fed controls was studied. The hind limbs of rats were unweighted by a tail suspension method and diets containing 0.1% to 2.4% calcium. After 2 weeks serum calcium, phosphorus, PTH and 1,25(OH)2D intestinal calcium transport were determined and bone mass, ash weight, and calcium in the tibia, L-1 vertebra, and humerus were measured. No significant differences in body weights were observed among the various groups. Suspended rats maintained constant levels of serum calcium and phosphate over the wide range of dietary calcium. Serum PTH and 1,25(OH)2D and intestinal calcium transport fell as dietary calcium was increased. Bone calcium in the tibia and vertebra from suspended rats remained less than that from pair-fed control. It is suggested that although no striking difference between suspended and control animals was observed in response to dieteary calcium, increasing dietary calcium may reduce the negative impact of unloading on the calcium content of the unweighted bones. The salutary effect of high dietary calcium appears to be due to inhibition of bone resorption rather than to stimulation of bone formation.

Calcium metabolism and cardiovascular function after spaceflight

NASA Technical Reports Server (NTRS)

Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric;

Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

PubMed Central

Wilson, Rosamund J; Copley, J Brian

2017-01-01

Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Findings Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Conclusion Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance. PMID:28182142

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT WITH SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

Extracellular Calcium Has Multiple Targets to Control Cell Proliferation.

PubMed

Capiod, Thierry

2016-01-01

Calcium channels and the two G-protein coupled receptors sensing extracellular calcium, calcium-sensing receptor (CaSR) and GPRC6a, are the two main means by which extracellular calcium can signal to cells and regulate many cellular processes including cell proliferation, migration and invasion of tumoral cells. Many intracellular signaling pathways are sensitive to cytosolic calcium rises and conversely intracellular signaling pathways can modulate calcium channel expression and activity. Calcium channels are undoubtedly involved in the former while the CaSR and GPRC6a are most likely to interfere with the latter. As for neurotransmitters, calcium ions use plasma membrane channels and GPCR to trigger cytosolic free calcium concentration rises and intracellular signaling and regulatory pathways activation. Calcium sensing GPCR, CaSR and GPRC6a, allow a supplemental degree of control and as for metabotropic receptors, they not only modulate calcium channel expression but they may also control calcium-dependent K+ channels. The multiplicity of intracellular signaling pathways involved, their sensitivity to local and global intracellular calcium increase and to CaSR and GPRC6a stimulation, the presence of membrane signalplex, all this confers the cells the plasticity they need to convert the effects of extracellular calcium into complex physiological responses and therefore determine their fate.

Discrete-State Stochastic Models of Calcium-Regulated Calcium Influx and Subspace Dynamics Are Not Well-Approximated by ODEs That Neglect Concentration Fluctuations

PubMed Central

Weinberg, Seth H.; Smith, Gregory D.

2012-01-01

Cardiac myocyte calcium signaling is often modeled using deterministic ordinary differential equations (ODEs) and mass-action kinetics. However, spatially restricted “domains” associated with calcium influx are small enough (e.g., 10−17 liters) that local signaling may involve 1–100 calcium ions. Is it appropriate to model the dynamics of subspace calcium using deterministic ODEs or, alternatively, do we require stochastic descriptions that account for the fundamentally discrete nature of these local calcium signals? To address this question, we constructed a minimal Markov model of a calcium-regulated calcium channel and associated subspace. We compared the expected value of fluctuating subspace calcium concentration (a result that accounts for the small subspace volume) with the corresponding deterministic model (an approximation that assumes large system size). When subspace calcium did not regulate calcium influx, the deterministic and stochastic descriptions agreed. However, when calcium binding altered channel activity in the model, the continuous deterministic description often deviated significantly from the discrete stochastic model, unless the subspace volume is unrealistically large and/or the kinetics of the calcium binding are sufficiently fast. This principle was also demonstrated using a physiologically realistic model of calmodulin regulation of L-type calcium channels introduced by Yue and coworkers. PMID:23509597

Calcium regulation in crustaceans during the molt cycle: a review and update.

PubMed

Ahearn, Gregory A; Mandal, Prabir K; Mandal, Anita

2004-02-01

Epithelial cells of the gut, gills, antennal glands and integument regulate calcium concentrations in crustaceans during the molt cycle. A cellular calcium transport model has been proposed suggesting the presence of calcium pumps, cation antiporters and calcium channels in transporting epithelial membranes that regulate the movements of this cation across the cell layer. Basolateral calcium transport during postmolt appears mainly regulated by the low affinity NCX antiporter, while calcium regulating 'housekeeping' activities of these cells in intermolt are controlled by the high affinity calcium ATPase (PMCA). A model is proposed for the involvement of the epithelial ER in the massive transepithelial calcium fluxes that occur during premolt and postmolt. This model involves the endoplasmic reticulum SERCA and RyR proteins and proposed cytoplasmic unstirred layers adjacent to apical and basolateral plasma membranes where calcium activities may largely exceed those in the bulk cytoplasmic phase. A result of the proposed transepithelial calcium transport model is that large quantities of calcium can be moved through these cells by these processes without affecting the low, and carefully controlled, bulk cytoplasmic calcium activities.

PRESENILIN-NULL CELLS HAVE ALTERED TWO-PORE CALCIUM CHANNEL EXPRESSION AND LYSOSOMAL CALCIUM; IMPLICATIONS FOR LYSOSOMAL FUNCTION

PubMed Central

Kayala, Kara M Neely; Dickinson, George D; Minassian, Anet; Walls, Ken C; Green, Kim N; LaFerla, Frank M

2012-01-01

Presenilins are necessary for calcium homeostasis and also for efficient proteolysis through the autophagy/lysosome system. Presenilin regulates both endoplasmic reticulum calcium stores and autophagic proteolysis in a γ-secretase independent fashion. The endo-lysosome system can also act as a calcium store, with calcium efflux channels being recently identified as two-pore channels 1 and 2. Here we investigated lysosomal calcium content and the channels that mediate calcium release from these acidic stores in presenilin knockout cells. We report that presenilin loss leads to a lower total lysosomal calcium store despite the buildup of lysosomes found in these cells. Additionally, we find alterations in two-pore calcium channel protein expression, with loss of presenilin preventing the formation of a high molecular weight species of TPC1 and TPC2. Finally, we find that treatments that disturb lysosomal calcium release lead to a reduction in autophagy function yet lysosomal inhibitors do not alter two-pore calcium channel expression. These data indicate that alterations in lysosomal calcium in the absence of presenilins might be leading to disruptions in autophagy. PMID:23103503

Dietary calcium requirements do not differ between Mexican-American boys and girls.

PubMed

Palacios, Cristina; Martin, Berdine R; McCabe, George P; McCabe, Linda; Peacock, Munro; Weaver, Connie M

2014-08-01

Mexican Americans are an understudied ethnic group for determinants of bone health, although the risk of age-related osteoporosis is high in this rapidly growing sector of the U.S. population. Thus, the objective of the present study was to establish the dietary calcium requirements for bone health in Mexican-American adolescents by measuring calcium retention calculated from balance in response to a range of dietary calcium intakes and to determine predictors of skeletal calcium retention. Adolescents aged 12-15 y were studied twice on paired calcium intakes ranging from 600 to 2300 mg/d using randomized-order, crossover 3-wk balance studies. Skeletal calcium retention was calculated as dietary calcium intake minus calcium excreted in feces and urine over the last 2 wk of balance. A linear model was developed to explain the variation in calcium retention. Boys (n = 20) were taller and had higher lean mass, usual dietary calcium intake, bone mineral content, and serum alkaline phosphatase compared with girls, whereas girls (n = 20) had higher Tanner scores and greater fat mass. Calcium retention increased with calcium intake (P < 0.0001) and did not differ by sex (P = 0.66). In boys and girls considered together, calcium intake explained 33% of the variation in calcium retention. Serum alkaline phosphatase explained an additional 11% of the variation in calcium retention. Other variables measured, including the urine N-telopeptide of type I collagen/creatinine ratio, Tanner score, serum parathyroid hormone and 25-hydroxyvitamin D, weight, height, and body mass index, did not contribute to the variance in calcium retention. In adolescence, calcium retention in both Mexican-American boys and girls was higher than determined previously in adolescent nonHispanic white girls. This trial was registered at clinicaltrials.gov as NCT01277185. © 2014 American Society for Nutrition.

Prolonged exposure to 1,25(OH)2D3 and high ionized calcium induces FGF-23 production in intestinal epithelium-like Caco-2 monolayer: A local negative feedback for preventing excessive calcium transport.

PubMed

Rodrat, Mayuree; Wongdee, Kannikar; Panupinthu, Nattapon; Thongbunchoo, Jirawan; Teerapornpuntakit, Jarinthorn; Krishnamra, Nateetip; Charoenphandhu, Narattaphol

2018-02-15

Overdose of oral calcium supplement and excessive intestinal calcium absorption can contribute pathophysiological conditions, e.g., nephrolithiasis, vascular calcification, dementia, and cardiovascular accident. Since our previous investigation has indicated that fibroblast growth factor (FGF)-23 could abolish the 1,25-dihydroxyvitamin D 3 [1,25(OH) 2 D 3 ]-enhanced calcium absorption, we further hypothesized that FGF-23 produced locally in the enterocytes might be part of a local negative feedback loop to regulate calcium absorption. Herein, 1,25(OH) 2 D 3 was found to enhance the transcellular calcium transport across the epithelium-like Caco-2 monolayer, and this stimulatory effect was diminished by preceding prolonged exposure to high-dose 1,25(OH) 2 D 3 or high concentration of apical ionized calcium. Pretreatment with a neutralizing antibody for FGF-23 prevented this negative feedback regulation of calcium hyperabsorption induced by 1,25(OH) 2 D 3 . FGF-23 exposure completely abolished the 1,25(OH) 2 D 3 -enhanced calcium transport. Western blot analysis revealed that FGF-23 expression was upregulated in a dose-dependent manner by 1,25(OH) 2 D 3 or apical calcium exposure. Finally, calcium-sensing receptor (CaSR) inhibitors were found to prevent the apical calcium-induced suppression of calcium transport. In conclusion, prolonged exposure to high apical calcium and calcium hyperabsorption were sensed by CaSR, which, in turn, increased FGF-23 expression to suppress calcium transport. This local negative feedback loop can help prevent unnecessary calcium uptake and its detrimental consequences. Copyright © 2018 Elsevier Inc. All rights reserved.

The Association Between Calcium, Magnesium, and Ratio of Calcium/Magnesium in Seminal Plasma and Sperm Quality.

PubMed

Liang, Hong; Miao, Maohua; Chen, Jianping; Chen, Kanglian; Wu, Bin; Dai, Qi; Wang, Jian; Sun, Fei; Shi, Huijuan; Yuan, Wei

2016-11-01

The study aimed to examine the relationships between calcium, magnesium, and calcium/magnesium ratio in semen plasma and sperm quality. It was a cross-sectional study based on a program aiming at promoting the reproductive health in less-developed areas. A total of 515 men aged between 18 and 55 years provided semen specimens at family planning clinics in Sandu County, Guizhou Province, China. Total calcium and magnesium concentrations in semen plasma were measured with flame atomic absorption spectrometry. Sperm quality, including sperm motility and concentration, was evaluated by using a computer-assisted sperm analysis method. The medians of seminal plasma calcium, magnesium, and zinc concentrations were 9.61, 4.41, and 2.23 mmol/l, respectively. Calcium concentration and calcium/magnesium ratio were negatively associated with sperm concentrations (β = -0.47, P = 0.0123 for calcium; β = -0.25, P = 0.0393 for calcium/magnesium ratio) after adjusting for zinc and other covariates. In stratified analyses, the association between calcium and sperm concentrations only persisted among subjects with a calcium/magnesium ratio of ≤2.5 (β = -0.71, P = 0.0268). In the same stratum, magnesium was associated with increased sperm concentration (β = 0.73, P = 0.0386). Among subjects with a calcium/magnesium ratio of >2.5, neither calcium nor magnesium was associated with sperm concentration. In conclusion, total calcium and magnesium concentrations were associated with sperm concentration among subjects with a lower calcium/magnesium ratio. The calcium and magnesium ratio had a modifying effect on the associations of calcium and magnesium with sperm concentration.

Analysis of Spontaneous and Nerve-Evoked Calcium Transients in Intact Extraocular Muscles in Vitro

PubMed Central

Feng, Cheng-Yuan; Hennig, Grant W.; Corrigan, Robert D.; Smith, Terence K.; von Bartheld, Christopher S.

2012-01-01

Extraocular muscles (EOMs) have unique calcium handling properties, yet little is known about the dynamics of calcium events underlying ultrafast and tonic contractions in myofibers of intact EOMs. Superior oblique EOMs of juvenile chickens were dissected with their nerve attached, maintained in oxygenated Krebs buffer, and loaded with fluo-4. Spontaneous and nerve stimulation-evoked calcium transients were recorded and, following calcium imaging, some EOMs were double-labeled with rhodamine-conjugated alpha-bungarotoxin (rhBTX) to identify EOM myofiber types. EOMs showed two main types of spontaneous calcium transients, one slow type (calcium waves with 1/2max duration of 2–12 s, velocity of 25–50 μm/s) and two fast “flash-like” types (Type 1, 30–90 ms; Type 2, 90–150 ms 1/2max duration). Single pulse nerve stimulation evoked fast calcium transients identical to the fast (Type 1) calcium transients. Calcium waves were accompanied by a local myofiber contraction that followed the calcium transient wavefront. The magnitude of calcium-wave induced myofiber contraction far exceeded those of movement induced by nerve stimulation and associated fast calcium transients. Tetrodotoxin eliminated nerve-evoked transients, but not spontaneous transients. Alpha-bungarotoxin eliminated both spontaneous and nerve-evoked fast calcium transients, but not calcium waves, and caffeine increased wave activity. Calcium waves were observed in myofibers lacking spontaneous or evoked fast transients, suggestive of multiply-innervated myofibers, and this was confirmed by double-labeling with rhBTX. We propose that the abundant spontaneous calcium transients and calcium waves with localized contractions that do not depend on innervation may contribute to intrinsic generation of tonic functions of EOMs. PMID:22579493

Calcium movements and the cellular basis of gravitropism

NASA Astrophysics Data System (ADS)

Roux, S. J.; Biro, R. L.; Hale, C. C.

An early gravity-transduction event in oat coleoptiles which precedes any noticeable bending is the accumulation of calcium on their prospective slower-growing side. Sub-cellular calcium localization studies indicate that the gravity-stimulated redistribution of calcium results in an increased concentration of calcium in the walls of responding cells. Since calcium can inhibit the extension growth of plant cell walls, this selective accumulation of calcium in walls may play a role in inducing the asymmetry of growth which characterizes gravitropism. The active transport of calcium from cells into walls is performed by a calcium-dependent ATPase localized in the plasma membrane. Evidence is presented in support of the hypothesis that this calcium pump is regulated by a feed-back mechanism which includes the participation of calmodulin.

Effect of Potassium Citrate on Calcium Phosphate Stones in a Model of Hypercalciuria

PubMed Central

Asplin, John R.; Frick, Kevin K.; Granja, Ignacio; Culbertson, Christopher D.; Ng, Adeline; Grynpas, Marc D.; Bushinsky, David A.

2015-01-01

Potassium citrate is prescribed to decrease stone recurrence in patients with calcium nephrolithiasis. Citrate binds intestinal and urine calcium and increases urine pH. Citrate, metabolized to bicarbonate, should decrease calcium excretion by reducing bone resorption and increasing renal calcium reabsorption. However, citrate binding to intestinal calcium may increase absorption and renal excretion of both phosphate and oxalate. Thus, the effect of potassium citrate on urine calcium oxalate and calcium phosphate supersaturation and stone formation is complex and difficult to predict. To study the effects of potassium citrate on urine supersaturation and stone formation, we utilized 95th-generation inbred genetic hypercalciuric stone-forming rats. Rats were fed a fixed amount of a normal calcium (1.2%) diet supplemented with potassium citrate or potassium chloride (each 4 mmol/d) for 18 weeks. Urine was collected at 6, 12, and 18 weeks. At 18 weeks, stone formation was visualized by radiography. Urine citrate, phosphate, oxalate, and pH levels were higher and urine calcium level was lower in rats fed potassium citrate. Furthermore, calcium oxalate and calcium phosphate supersaturation were higher with potassium citrate; however, uric acid supersaturation was lower. Both groups had similar numbers of exclusively calcium phosphate stones. Thus, potassium citrate effectively raises urine citrate levels and lowers urine calcium levels; however, the increases in urine pH, oxalate, and phosphate levels lead to increased calcium oxalate and calcium phosphate supersaturation. Potassium citrate induces complex changes in urine chemistries and resultant supersaturation, which may not be beneficial in preventing calcium phosphate stone formation. PMID:25855777

21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

Code of Federal Regulations, 2010 CFR

2010-04-01

... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.330 Calcium pantothenate, calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

Code of Federal Regulations, 2012 CFR

2012-04-01

... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.330 Calcium pantothenate, calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

Code of Federal Regulations, 2013 CFR

2013-04-01

... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.330 Calcium pantothenate, calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING ON LEFT, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING ON LEFT, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT OF CENTER WITH TOP OF SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

Calcium-deficiency assessment and biomarker identification by an integrated urinary metabonomics analysis

PubMed Central

2013-01-01

Background Calcium deficiency is a global public-health problem. Although the initial stage of calcium deficiency can lead to metabolic alterations or potential pathological changes, calcium deficiency is difficult to diagnose accurately. Moreover, the details of the molecular mechanism of calcium deficiency remain somewhat elusive. To accurately assess and provide appropriate nutritional intervention, we carried out a global analysis of metabolic alterations in response to calcium deficiency. Methods The metabolic alterations associated with calcium deficiency were first investigated in a rat model, using urinary metabonomics based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and multivariate statistical analysis. Correlations between dietary calcium intake and the biomarkers identified from the rat model were further analyzed to confirm the potential application of these biomarkers in humans. Results Urinary metabolic-profiling analysis could preliminarily distinguish between calcium-deficient and non-deficient rats after a 2-week low-calcium diet. We established an integrated metabonomics strategy for identifying reliable biomarkers of calcium deficiency using a time-course analysis of discriminating metabolites in a low-calcium diet experiment, repeating the low-calcium diet experiment and performing a calcium-supplement experiment. In total, 27 biomarkers were identified, including glycine, oxoglutaric acid, pyrophosphoric acid, sebacic acid, pseudouridine, indoxyl sulfate, taurine, and phenylacetylglycine. The integrated urinary metabonomics analysis, which combined biomarkers with regular trends of change (types A, B, and C), could accurately assess calcium-deficient rats at different stages and clarify the dynamic pathophysiological changes and molecular mechanism of calcium deficiency in detail. Significant correlations between calcium intake and two biomarkers, pseudouridine (Pearson correlation, r = 0.53, P = 0.0001) and citrate (Pearson correlation, r = -0.43, P = 0.001), were further confirmed in 70 women. Conclusions To our knowledge, this is the first report of reliable biomarkers of calcium deficiency, which were identified using an integrated strategy. The identified biomarkers give new insights into the pathophysiological changes and molecular mechanisms of calcium deficiency. The correlations between calcium intake and two of the biomarkers provide a rationale or potential for further assessment and elucidation of the metabolic responses of calcium deficiency in humans. PMID:23537001

Roles of calcium and pH in activation of eggs of the medaka fish, Oryzias latipes

PubMed Central

1983-01-01

Unfertilized eggs of the medaka fish (Oryzias latipes) were injected with pH-buffered calcium buffers. Medaka egg activation is accompanied by a transient increase in cytoplasmic free calcium (Gilkey, J. C., L. F. Jaffe, E. B. Ridgway, and G. T. Reynolds, 1978, J. Cell Biol., 76:448-466). The calcium buffer injections demonstrated that (a) the threshold free calcium required to elicit the calcium transient and activate the egg is between 1.7 and 5.1 microM at pH 7.0, well below the 30 microM reached during the transient, and (b) buffers which hold free calcium below threshold prevent activation of the buffered region in subsequently fertilized eggs. Therefore an increase in free calcium is necessary and sufficient to elicit the calcium transient, and the calcium transient is necessary to activate the egg. Further, these results are additional proof that the calcium transient is initiated and propagated through the cytoplasm by a mechanism of calcium- stimulated calcium release. Finally, a normal calcium transient must propagate through the entire cytoplasm to ensure normal development. Unfertilized eggs were injected with pH buffers to produce short-term, localized changes in cytoplasmic pH. The eggs were then fertilized at various times after injection. In other experiments, unfertilized and fertilized eggs were exposed to media containing either NH4Cl or CO2 to produce longer term, global changes in cytoplasmic pH. These treatments neither activated the eggs nor interfered with the normal development of fertilized eggs, suggesting that even if a natural change in cytoplasmic pH is induced by activation, it has no role in medaka egg development. The injected pH buffers altered the rate of propagation of the calcium transient through the cytoplasm, suggesting that the threshold free calcium required to trigger calcium-stimulated calcium release might be pH dependent. The results of injection of pH-buffered calcium buffers support this conjecture: for a tenfold increase in hydrogen ion concentration, free calcium must also be raised tenfold to elicit the calcium transient. PMID:6411737

Evaluation of calcium ion, hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments: An in vitro study

PubMed Central

Fulzele, Punit; Baliga, Sudhindra; Thosar, Nilima; Pradhan, Debaprya

2011-01-01

Aims: Evaluation of calcium ion and hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments. Objective: The purpose of this study was to evaluate calcium and hydroxyl ion release and pH levels of calcium hydroxide based products, namely, RC Cal, Metapex, calcium hydroxide with distilled water, along with the new gutta-percha points with calcium hydroxide. Materials and Methods: The materials were inserted in polyethylene tubes and immersed in deionized water. The pH variation, Ca++ and OH- release were monitored periodically for 1 week. Statistical Analysis Used: Statistical analysis was carried out using one-way analysis of variance and Tukey's post hoc tests with PASW Statistics version 18 software to compare the statistical difference. Results: After 1 week, calcium hydroxide with distilled water and RC Cal raised the pH to 12.7 and 11.8, respectively, while a small change was observed for Metapex, calcium hydroxide gutta-percha points. The calcium released after 1 week was 15.36 mg/dL from RC Cal, followed by 13.04, 1.296, 3.064 mg/dL from calcium hydroxide with sterile water, Metapex and calcium hydroxide gutta-percha points, respectively. Conclusions: Calcium hydroxide with sterile water and RC Cal pastes liberate significantly more calcium and hydroxyl ions and raise the pH higher than Metapex and calcium hydroxidegutta-percha points. PMID:22346155

Significance of Ca-soap formation for calcium absorption in the rat.

PubMed Central

Gacs, G; Barltrop, D

1977-01-01

The significance of calcium soap formation in the inhibition of calcium absorption has been studied in rats. 47Ca labelled soaps of fatty acids were introduced into the duodenum and the absorption of calcium measured after four hours in a whole body counter. The absorption of calcium was inversely correlated with the chain length of the fatty acid varying from 1% for Ca-stearate to 60% for Ca-hexanoate. Increasing the degree of unsaturation of the fatty acid was accompanied by increased calcium absorption. The availability of calcium for absorption from the soaps was correlated with their solubility in 1% aqueous Na-tauroglycocholate. The percentages of calcium as soap in the small intestine and the faeces after intragastric administration of calcium and fats were similar, which suggests that the faecal content of calcium soaps is an index of intestinal soap formation. Soap formation was negligible when CaCl2 was given with tristearate, triolaeate, or tridecanoate and no depression of calcium absorption was observed. Calcium absorption was markedly impaired by the addition of phosphates at a Ca/P ratio of 1:1 irrespective of the presence of neutral fats. Stearic acid resulted in significant soap formation and reduced calcium absorption. The degree of Ca-soap formation and the inhibition of calcium absorption were well correlated. The results suggest that, although calcium soap formation may markedly depress calcium absorption in the rat, no significant soap formation takes place when fats are given in the form of triglycerides. PMID:838405

Calcium homeostasis in intraerythrocytic malaria parasites.

PubMed

Garcia, C R; Dluzewski, A R; Catalani, L H; Burting, R; Hoyland, J; Mason, W T

1996-12-01

The fluorescent indicator, fura-2, AM, was used to measure free calcium concentrations in the intraerythrocytic malaria parasites of Plasmodium chabaudi and Plasmodium falciparum. In both species the free cytosolic calcium concentration was maintained at low levels (between 40 and 100 nM throughout the maturation process. Digital image analysis of the indicator fluorescence was performed on parasites and evaluated with the aid of a calibration of the calcium response, based on permeabilized parasites, exposed to calcium buffers. This again revealed that free calcium concentrations in the intact parasite are maintained at a predetermined level, regardless of the free calcium in the surrounding milieu. Both species of parasites are thus capable of regulating their internal free calcium levels with high precision, presumably by means of calcium pump ATPases. A small but significant elevation of the cytosolic free calcium concentration by the tumor promoter, thapsigargin, may be taken to reflect the presence of calcium stores in the endoplasmic reticulum in P. falciparum.

Calcium ionization balance and argon/calcium abundance in solar flares

NASA Astrophysics Data System (ADS)

Antonucci, E.; Marocchi, D.; Gabriel, A. H.; Doschek, G. A.

1987-12-01

An earlier analysis of solar flare calcium spectra from XRP and P78-1 aimed at measuring the calcium ionization balance resulted in an ambiguity due to a line blend between the calcium q line and an Ar XVII line. In the present work the calcium line 'r' is included in the analysis in order to resolve this problem. It is shown that the correct calcium ionization balance is that indicated in the earlier paper as corresponding to an argon/calcium abundance ratio of 0.2. The argon/calcium abundance ratio in the group of solar flares studied is shown to be 0.2 + or - 0.2. It is further argued that while the abundance of heavy elements may be enhanced in energetic flare events, this enhancement is less for argon than for calcium, leading to an argon/calcium ratio smaller than that present in the quiet sun.

21 CFR 184.1212 - Calcium pantothenate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium pantothenate. 184.1212 Section 184.1212... Listing of Specific Substances Affirmed as GRAS § 184.1212 Calcium pantothenate. (a) Calcium pantothenate... and the DL-racemic mixture of calcium pantothenate are used in food. Commercial calcium pantothenate...

21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

Code of Federal Regulations, 2014 CFR

2014-04-01

... SERVICES (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.330 Calcium pantothenate, calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may be safely used in foods for special...

Absorption of Levothyroxine When Coadministered with Various Calcium Formulations

PubMed Central

Zamfirescu, Isabelle

2011-01-01

Background Calcium carbonate is a commonly used dietary supplement and has been shown to interfere with levothyroxine absorption. However, calcium citrate, which is also used for supplementation purposes, has not been studied previously and calcium acetate, which is used to treat hyperphosphatemia in renal failure, has been reported to show little or no interference with levothyroxine absorption in a retrospective pharmacoepidemiologic study. We aimed to compare the effect of these three calcium formulations on levothyroxine absorption. Materials and Methods The study was conducted in eight healthy, euthyroid adults. We performed single-dose pharmacokinetic studies in which we measured levothyroxine absorption when given alone or when coadministered with calcium carbonate, calcium citrate, or calcium acetate in doses containing 500 mg elemental calcium. Serum thyroxine was measured at intervals over a 6-hour period after ingestion of the study drugs. Results Coadministration of each of the three calcium preparations significantly reduced levothyroxine absorption by about 20%–25% compared with levothyroxine given alone. Conclusions Contrary to a prior report, our data suggest that calcium acetate interferes with levothyroxine absorption in a manner similar to that seen with calcium carbonate and calcium citrate. Although the effect of calcium is modest compared with some other medications previously studied, hypothyroid patients should be cautioned to take their levothyroxine well-separated from all of these calcium formulations. PMID:21595516

Use of Genetically-encoded Calcium Indicators for Live Cell Calcium Imaging and Localization in Virus-infected Cells

PubMed Central

Perry, Jacob L.; Ramachandran, Nina K.; Utama, Budi; Hyser, Joseph M.

2015-01-01

Calcium signaling is a ubiquitous and versatile process involved in nearly every cellular process, and exploitation of host calcium signals is a common strategy used by viruses to facilitate replication and cause disease. Small molecule fluorescent calcium dyes have been used by many to examine changes in host cell calcium signaling and calcium channel activation during virus infections, but disadvantages of these dyes, including poor loading and poor long-term retention, complicate analysis of calcium imaging in virus-infected cells due to changes in cell physiology and membrane integrity. The recent expansion of genetically-encoded calcium indicators (GECIs), including blue and red-shifted color variants and variants with calcium affinities appropriate for calcium storage organelles like the endoplasmic reticulum (ER), make the use of GECIs an attractive alternative for calcium imaging in the context of virus infections. Here we describe the development and testing of cell lines stably expressing both green cytoplasmic (GCaMP5G and GCaMP6s) and red ER-targeted (RCEPIAer) GECIs. Using three viruses (rotavirus, poliovirus and respiratory syncytial virus) previously shown to disrupt host calcium homeostasis, we show the GECI cell lines can be used to detect simultaneous cytoplasmic and ER calcium signals. Further, we demonstrate the GECI expression has sufficient stability to enable long-term confocal imaging of both cytoplasmic and ER calcium during the course of virus infections. PMID:26344758

Increased calcium absorption from synthetic stable amorphous calcium carbonate: Double-blind randomized crossover clinical trial in post-menopausal women

USDA-ARS?s Scientific Manuscript database

Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (C...

The Role of Calcium in Prevention and Treatment of Osteoporosis.

ERIC Educational Resources Information Center

Heaney, Robert P.

1987-01-01

Osteoporosis results from several factors. Calcium deficiency is only one, and high calcium intake will prevent only those cases in which calcium is the limiting factor. Calcium cannot reverse, but only arrest, bone loss. A high calcium intake for every member of the population is advocated. (Author/MT)

Calcium kinetics during bed rest with artificial gravity and exercise countermeasures

USDA-ARS?s Scientific Manuscript database

We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest. Subjects ingested less calcium during bed rest, and with artificial gravity, they also absorbed less calcium. With exercise, they excreted less calcium. To retain bone during bed rest, calcium intake ne...

Masters or slaves? Vesicle release machinery and the regulation of presynaptic calcium channels.

PubMed

Jarvis, Scott E; Zamponi, Gerald W

2005-05-01

Calcium entry through presynaptic voltage-gated calcium channels is essential for neurotransmitter release. The two major types of presynaptic calcium channels contain a synaptic protein interaction site that physically interacts with synaptic vesicle release proteins. This is thought to tighten the coupling between the sources of calcium entry and the neurotransmitter release machinery. Conversely, the binding of synaptic proteins to presynaptic calcium channels regulates calcium channel activity. Hence, presynaptic calcium channels act not only as the masters of the synaptic release process, but also as key targets for feedback inhibition.

The calcium-sensing receptor regulates mammary gland parathyroid hormone–related protein production and calcium transport

PubMed Central

VanHouten, Joshua; Dann, Pamela; McGeoch, Grace; Brown, Edward M.; Krapcho, Karen; Neville, Margaret; Wysolmerski, John J.

2004-01-01

The transfer of calcium from mother to milk during lactation is poorly understood. In this report, we demonstrate that parathyroid hormone–related protein (PTHrP) production and calcium transport in mammary epithelial cells are regulated by extracellular calcium acting through the calcium-sensing receptor (CaR). The CaR becomes expressed on mammary epithelial cells at the transition from pregnancy to lactation. Increasing concentrations of calcium, neomycin, and a calcimimetic compound suppress PTHrP secretion by mammary epithelial cells in vitro, whereas in vivo, systemic hypocalcemia increases PTHrP production, an effect that can be prevented by treatment with a calcimimetic. Hypocalcemia also reduces overall milk production and calcium content, while increasing milk osmolality and protein concentrations. The changes in milk calcium content, milk osmolality, and milk protein concentration were mitigated by calcimimetic infusions. Finally, in a three-dimensional culture system that recapitulates the lactating alveolus, activation of the basolateral CaR increases transcellular calcium transport independent of its effect on PTHrP. We conclude that the lactating mammary gland can sense calcium and adjusts its secretion of calcium, PTHrP, and perhaps water in response to changes in extracellular calcium concentration. We believe this defines a homeostatic system that helps to match milk production to the availability of calcium. PMID:14966569

Effects of Eggshell Calcium Supplementation on Bone Mass in Postmenopausal Vietnamese Women.

PubMed

Sakai, Seigo; Hien, Vu Thi Thu; Tuyen, Le Danh; Duc, Ha Anh; Masuda, Yasunobu; Yamamoto, Shigeru

2017-01-01

Bone mass decreases along with aging, especially for women after menopause because of lower estrogen secretion together with low calcium intake. This study was conducted to study the effect of eggshell calcium supplementation on bone mass in 54 postmenopausal Vietnamese women living in a farming area about 60 km from Hanoi, Vietnam. Sets of 3 subjects matched by age, bone mass, BMI and calcium intake were divided randomly into 3 groups with 18 subjects in each group. The eggshell calcium group was administered 300 mg/d calcium from eggshell, the calcium carbonate group 300 mg/d calcium from calcium carbonate and the placebo group received no calcium supplementation. Bone mass (Speed of Sound (SOS)) was measured at the beginning (the baseline), the middle (6th month) and the end of the study (12th month) by the single blind method. SOS of the eggshell group increased significantly at 12 mo (p<0.05) and was significantly higher than that of the placebo and calcium carbonate groups at 12 mo (p<0.05). The SOS of the calcium carbonate group tended to be higher than that of the placebo group but without a significant difference (p>0.05). In conclusion, eggshell calcium was more effective in increasing bone mass than calcium carbonate in postmenopausal Vietnamese women.

Calcium deprivation increases the palatability of calcium solutions in rats.

PubMed

McCaughey, Stuart A; Forestell, Catherine A; Tordoff, Michael G

2005-02-15

Calcium-deprived rats have elevated intakes of CaCl2, other calcium salts, and some non-calcium compounds. We used taste reactivity to examine the effects of calcium deprivation on the palatability of CaCl2 and other solutions. Nine male Sprague-Dawley rats were calcium-deprived by maintenance on a low-calcium diet, and eight replete rats were used as controls. All rats were videotaped during intraoral infusion of the following solutions: 30 and 300 mM CaCl2, 30 mM calcium lactate, 100 and 600 mM NaCl, 30 mM MgCl2, 1 mM quinine.HCl, 2.5 mM sodium saccharin, and deionized water. We counted individual orofacial and somatic movements elicited by the infusions and used them to calculate total ingestive and aversive scores. Relative to controls, calcium-deprived rats gave a significantly larger number of tongue protrusions and had higher total ingestive scores for CaCl2, calcium lactate, NaCl, and MgCl2. Our results suggest that CaCl2, calcium lactate, NaCl, and MgCl2 taste more palatable to rats when they are calcium-deprived than replete, and this may be responsible for the increased intake of these solutions following calcium deprivation.

Vitamin D Status and Calcium Metabolism in Adolescent Black and White Girls on a Range of Controlled Calcium Intakes

PubMed Central

Weaver, Connie M.; McCabe, Linda D.; McCabe, George P.; Braun, Michelle; Martin, Berdine R.; DiMeglio, Linda A.; Peacock, Munro

2008-01-01

Background: There are limited data in adolescents on racial differences in relationships between dietary calcium intake, absorption, and retention and serum levels of calcium-regulating hormones. Objectives: The aim of this study was to investigate these relationships cross-sectionally in American White and Black adolescent girls. Methods: Calcium balance studies were conducted in 105 girls, aged 11–15 yr, on daily calcium intakes ranging from 760–2195 mg for 3-wk controlled feeding periods; 158 observations from 52 Black and 53 White girls were analyzed. Results: Black girls had lower serum 25-hydroxyvitamin D [25(OH)D], higher serum 1,25-dihydroxyvitamin D, and higher calcium absorption and retention than White girls. Calcium intake and race, but not serum 25(OH)D, predicted net calcium absorption and retention with Black girls absorbing calcium more efficiently at low calcium intakes than White girls. The relationship between serum 25(OH)D and serum PTH was negative only in White girls. Calcium intake, race, and postmenarcheal age explained 21% of the variation in calcium retention, and serum 25(OH)D did not contribute further to the variance. Conclusions: These results suggest that serum 25(OH)D does not contribute to the racial differences in calcium absorption and retention during puberty. PMID:18682505

[Effects of fertilizing regime and planting age on soil calcium decline in Luochuan apple orchards].

PubMed

Li, Peng; Li, Chun Yue; Wang, Yi Quan; Jiao, Cai Qiang

2017-05-18

This study was conducted to assess the effects of fertilizing regime and orchard planting age on soil calcium contents and stocks in the apple orchards on the Loess Plateau. The apple orchards in Luochuan County, one of the best regions for apple plantation in the world, were selec-ted in this study. The contents of calcium carbonate,water-soluble calcium and exchangeable cal-cium at 0-100 cm soil layer under different fertilizing regimes and various planting ages were mea-sured, their stocks were calculated and their variation features were analyzed. The results showed that soil in the apple orchards in the study region was characterized by the decline in calcium contents. The decline was more serious in apple orchards with long-term application of chemical fertili-zer than in those with combined application of chemical fertilizer and farmyard manure. The average contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in apple orchards with long-term application of chemical fertilizer decreased by 38.8%, 25.4% and 5.6% respectively than those in the apple orchards with long-term application of both chemical fertilizer and farmyard manure. The stocks of calcium carbonate, water-soluble calcium and exchangeable calcium decreased by 36.4%, 26.0% and 4.3%, respectively. The decline of soil cal-cium was aggravated with the increase of orchard planting age. The contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in orchards of more than 25 years of planting age decreased by 48.8%, 69.4% and 39.5% respectively, compared with orchards of less than 10 years of planting age, and the stocks decreased by 40.8%, 64.1% and 33.0%, respectively. These results indicated that either long-term application of chemical fertilizer or long-term plantation of apple trees obviously depleted soil calcium carbonate, water-soluble calcium and exchangeable calcium. Therefore, it was recommended that application of chemical fertilizer and farmyard manure should be combined to mitigate soil calcium decline, and calcium management should be strengthened in apple orchards of more than 25 years of planting age. The fertilizing regime was a driving factor of soil calcium decline which had a significant temporal (orchard planting age) and spatial (soil depth) effect.

Dietary calcium deficiency in laying ducks impairs eggshell quality by suppressing shell biomineralization.

PubMed

Chen, Wei; Zhao, Fei; Tian, Zhi Mei; Zhang, Han Xing; Ruan, Dong; Li, Yan; Wang, Shuang; Zheng, Chun Tian; Lin, Ying Cai

2015-10-01

The objective of this study was to determine the effects of dietary calcium deficiency on the process of shell formation. Four hundred and fifty female ducks (Anas platyrhynchos) at 22 weeks were randomly assigned to three groups. Ducks were fed one of two calcium-deficient diets (containing 1.8% or 0.38% calcium, respectively) or a calcium-adequate control diet (containing 3.6% calcium) for 67 days (depletion period) and then all ducks were fed a calcium-adequate diet for an additional 67 days (repletion period). Compared with the calcium-adequate control, the average shell thickness, egg shell weight, breaking strength, mammillae density and mammillary knob thickness of shell from ducks that consumed the diet with 0.38% calcium were significantly decreased (P<0.05) during the depletion period, accompanied by reduced tibia quality. The mRNA expression of both secreted phosphoprotein 1 (SPP1) and carbonic anhydrase 2 (CA2) in the uterus was decreased after feeding calcium-deficient diets (1.8% or 0.38% calcium). mRNA transcripts of calbindin 1 (CALB1), an important protein responsible for calcium transport, and the matrix protein genes ovocalyxin-32 (OCX-32) and ovocleidin-116 (OC-116) were reduced in ducks fed 0.38% calcium but not 1.8% calcium. Plasma estradiol concentration was decreased by both of the calcium-deficient diets (P<0.05). The impaired shell quality and suppressed functional proteins involved in shell formation could be reversed by repletion of dietary calcium. The results of the present study suggest that dietary calcium deficiency negatively affects eggshell quality and microarchitecture, probably by suppressing shell biomineralization. © 2015. Published by The Company of Biologists Ltd.

Calcium bioavailability and kinetics of calcium ascorbate and calcium acetate in rats.

PubMed

Cai, Jianwei; Zhang, Qinmin; Wastney, Meryl E; Weaver, Connie M

2004-01-01

The objective was to investigate the bioavailability and mechanism of calcium absorption of calcium ascorbate (ASC) and calcium acetate (AC). A series of studies was performed in adult Sprague-Dawley male rats. In the first study, each group of rats (n = 10/group) was assigned to one of the five test meals labeled with (45)Ca: (i) 25 mg calcium as heated ASC or (ii) unheated ASC, (iii) 25 mg calcium as unheated AC, (iv) 3.6 mg Ca as unheated ASC, or (v) unheated AC. Femur uptake indicated better calcium bioavailability from ASC than AC at both calcium loads. A 5-min heat treatment partly reduced bioavailability of ASC. Kinetic studies were performed to further investigate the mechanism of superior calcium bioavailability from ASC. Two groups of rats (n = 10/group) received oral doses of 25 mg Ca as ASC or AC. Each dose contained 20 micro Ci (45)Ca. Two additional groups of rats (n = 10/group) received an intravenous injection (iv) of 10 micro Ci (45)Ca after receiving an unlabeled oral dose of 25 mg calcium as ASC or AC. Sequential blood samples were collected over 48 hrs. Urine and fecal samples were collected every 12 hrs for 48 hrs and were analyzed for total calcium and (45)Ca content. Total calcium and (45)Ca from serum, urine, and feces were fitted by a compartment kinetics model with saturable and nonsaturable absorption pathways by WinSAAM (Windows-based Simulation Analysis and Modeling). The difference in calcium bioavailability between the two salts was due to differences in saturable rather than passive intestinal absorption and not to endogenous secretion or calcium deposition rate. The higher bioavailability of calcium ascorbate was due to a longer transit time in the small intestine compared with ASC.

Calcium Intake in Elderly Australian Women Is Inadequate

PubMed Central

Meng, Xingqiong; Kerr, Deborah A.; Zhu, Kun; Devine, Amanda; Solah, Vicky; Binns, Colin W.; Prince, Richard L.

2010-01-01

The role of calcium in the prevention of bone loss in later life has been well established but little data exist on the adequacy of calcium intakes in elderly Australian women. The aim of this study was to compare the dietary intake including calcium of elderly Australian women with the Australian dietary recommendation, and to investigate the prevalence of calcium supplement use in this population. Community-dwelling women aged 70–80 years were randomly recruited using the Electoral Roll for a 2-year protein intervention study in Western Australia. Dietary intake was assessed at baseline by a 3-day weighed food record and analysed for energy, calcium and other nutrients. A total of 218 women were included in the analysis. Mean energy intake was 7,140 ± 1,518 kJ/day and protein provided 19 ± 4% of energy. Mean dietary calcium intake was 852 ± 298 mg/day, which is below Australian recommendations. Less than one quarter of women reported taking calcium supplements and only 3% reported taking vitamin D supplements. Calcium supplements by average provided calcium 122 ± 427 mg/day and when this was taken into account, total calcium intake increased to 955 ± 504 mg/day, which remained 13% lower than the Estimated Average Requirement (EAR, 1,100 mg/day) for women of this age group. The women taking calcium supplements had a higher calcium intake (1501 ± 573 mg) compared with the women on diet alone (813 ± 347 mg). The results of this study indicate that the majority of elderly women were not meeting their calcium requirements from diet alone. In order to achieve the recommended dietary calcium intake, better strategies for promoting increased calcium, from both diet and calcium supplements appears to be needed. PMID:22254072

Effects of nicergoline on calcium and magnesium deposition in the central nervous system tissues of rats maintained on low-calcium diets.

PubMed

Yasui, M; Kihira, T; Tsujimoto, M; Ota, K

1992-11-01

Reduction of calcium intake leads to the mobilization of calcium and magnesium from the bone pool and to calcium deposition in the soft tissues, especially in the central nervous system (CNS). The effects of 10 alpha-methoxy-1,6-dimethylergoline-8 beta-methanol 5-bromonicotinate (nicergoline), an ameliorator of cerebral circulation and metabolism, on the deposition of calcium and magnesium in the CNS, heart, liver, kidney, muscle, abdominal aorta and bones were studied in rats maintained on standard and low-calcium diets. Rats were fed the following diets for 90 days: standard calcium (12.5 g/kg); standard calcium with 60 mg/kg nicergoline; low-calcium (30 mg/kg); and low-calcium with 60 mg/kg nicergoline. The presence of nicergoline did not affect blood chemistry but magnesium concentrations in the liver were significantly (P < 0.05) higher in rats fed standard diet with nicergoline. Magnesium concentrations in the occipital cortex, pons, cerebellum, liver, kidney, muscle and femur of nicergoline-treated rats fed low-calcium diet were significantly (P < 0.01-0.05) higher compared with those in the corresponding controls, whereas the calcium concentrations in the femur of nicergoline-treated rats fed both standard and low-calcium diets were significantly (P < 0.05) higher than those in the corresponding controls. In general, nicergoline tended to preserve the calcium content in the bone of rats fed a standard diet. Nicergoline may be implicated in calcium metabolism in rats fed low-calcium diets and may activate cerebral metabolism through the maintenance of magnesium concentrations in the CNS and soft tissues.

TMEM203 Is a Novel Regulator of Intracellular Calcium Homeostasis and Is Required for Spermatogenesis

PubMed Central

Shambharkar, Prashant B.; Bittinger, Mark; Latario, Brian; Xiong, ZhaoHui; Bandyopadhyay, Somnath; Davis, Vanessa; Lin, Victor; Yang, Yi; Valdez, Reginald; Labow, Mark A.

2015-01-01

Intracellular calcium signaling is critical for initiating and sustaining diverse cellular functions including transcription, synaptic signaling, muscle contraction, apoptosis and fertilization. Trans-membrane 203 (TMEM203) was identified here in cDNA overexpression screens for proteins capable of modulating intracellular calcium levels using activation of a calcium/calcineurin regulated transcription factor as an indicator. Overexpression of TMEM203 resulted in a reduction of Endoplasmic Reticulum (ER) calcium stores and elevation in basal cytoplasmic calcium levels. TMEM203 protein was localized to the ER and found associated with a number of ER proteins which regulate ER calcium entry and efflux. Mouse Embryonic Fibroblasts (MEFs) derived from Tmem203 deficient mice had reduced ER calcium stores and altered calcium homeostasis. Tmem203 deficient mice were viable though male knockout mice were infertile and exhibited a severe block in spermiogenesis and spermiation. Expression profiling studies showed significant alternations in expression of calcium channels and pumps in testes and concurrently Tmem203 deficient spermatocytes demonstrated significantly altered calcium handling. Thus Tmem203 is an evolutionarily conserved regulator of cellular calcium homeostasis, is required for spermatogenesis and provides a causal link between intracellular calcium regulation and spermiogenesis. PMID:25996873

Analytical solution of reaction-diffusion equations for calcium wave propagation in a starburst amacrine cell.

PubMed

Poznanski, R R

2010-09-01

A reaction-diffusion model is presented to encapsulate calcium-induced calcium release (CICR) as a potential mechanism for somatofugal bias of dendritic calcium movement in starburst amacrine cells. Calcium dynamics involves a simple calcium extrusion (pump) and a buffering mechanism of calcium binding proteins homogeneously distributed over the plasma membrane of the endoplasmic reticulum within starburst amacrine cells. The system of reaction-diffusion equations in the excess buffer (or low calcium concentration) approximation are reformulated as a nonlinear Volterra integral equation which is solved analytically via a regular perturbation series expansion in response to calcium feedback from a continuously and uniformly distributed calcium sources. Calculation of luminal calcium diffusion in the absence of buffering enables a wave to travel at distances of 120 μm from the soma to distal tips of a starburst amacrine cell dendrite in 100 msec, yet in the presence of discretely distributed calcium-binding proteins it is unknown whether the propagating calcium wave-front in the somatofugal direction is further impeded by endogenous buffers. If so, this would indicate CICR to be an unlikely mechanism of retinal direction selectivity in starburst amacrine cells.

Calcium intake in the United States from dietary and supplemental sources across adult age groups: new estimates from the National Health and Nutrition Examination Survey 2003-2006.

PubMed

Mangano, Kelsey M; Walsh, Stephen J; Insogna, Karl L; Kenny, Anne M; Kerstetter, Jane E

2011-05-01

Adequate lifelong calcium intake is essential in optimizing bone health. Recent National Health and Nutrition Examination Survey data were used to quantify variation in calcium intake across adult age groups and to relate age-associated changes in calcium intake with energy intake. Additional goals were to assess differences in dietary calcium intake between supplemental calcium users and nonusers and to evaluate associations between age and calcium density in the diet. This cross-sectional analysis determined calcium and energy intake for National Health and Nutrition Examination Survey respondents during 2003-2006. Diet was assessed with 24-hour recall and supplement use via questionnaire. Trends in median intakes for dietary calcium, total calcium, and energy across age categories were assessed using survey analysis methods. Nutrient density was represented using calcium to energy intake ratios. The analyses included data from 9,475 adults. When compared to the 19- to 30-year age group, median dietary calcium intake was lower in the ≥81-year age group by 23% in men (P<0.001) and by 14% in women (P=0.003). These reductions coincided with 35% and 28% decreases, respectively, in median energy intake (P<0.001 for each sex). In contrast, the frequency of calcium supplement use increased (P<0.001) with age in both men and women. Yet, among female supplement users, the decline in median dietary calcium intake was greater than in nonusers (P=0.02). Calcium density in the diet significantly increased relative to age in men and women (P<0.001 for each sex); however, dietary and total calcium to energy ratios were insufficient to meet target ratios inferred by adequate intake standards after age 50 years. Although supplemental calcium use and calcium density were highest in older age groups, they were not sufficient in meeting recommended levels. New approaches to increasing the frequency and level of calcium supplement use to enhance calcium density in diets may be necessary to reduce osteoporosis risk among older Americans. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

A possible molecular mechanism of the action of digitalis: ouabain action on calcium binding to sites associated with a purified sodium-potassium-activated adenosine triphosphatase from kidney.

PubMed

Gervais, A; Lane, L K; Anner, B M; Lindenmayer, G E; Schwartz, A

1977-01-01

Calcium binding at 0 degrees C to a purified sheep kidney Na+,K+-ATPase was described by linear Scatchard plots. Binding at saturating free calcium was 65-80 nmol/mg of protein, or 30-40 mol of calcium/mol of enzyme. Aqueous emulsions of lipids extracted from Na+,K+-ATPase yielded dissociation constants and maximum calcium-binding values that were similar to those for native Na+,K+-ATPase. Phospholipase A treatment markedly reduced calcium binding. Pretreatment of native Na+,K+-ATPase with ouabain increased the dissociation constant for calcium binding from 131 +/- 7 to 192 +/- 7 muM without altering maximum calcium binding. Ouabain pretreatment did not affect calcium binding to extracted phospholipids, ouabain-insensitive ATPases, or heat denatured Na+,K+-ATPase, Na+ and K+ (5-20 mM) increased the dissociation constants for calcium, which suggests competition between the monovalent cations and calcium for the binding sites. At higher concentrations of monovalent cations, ouabain increased the apparent affinity of binding sites for calcium. Extrapolation to physiological cation concentrations revealed that the ouabain-induced increase in apparent affinity for calcium may be as much as 2- to 3-fold. These results suggest: (1) calcium binds to phospholipids associated with Na+,K+-ATPase; (2) ouabain interaction with Na+,K+-ATPase induces a perturbation that is transmitted to adjacent phospholipids, altering their affinity for calcium; and (3) at physiological concentrations of Na+ or K+, or both, ouabain interaction with Na+,K+-ATPase may lead to an increased pool of membrane-bound calcium.

Comparison of the Absorption of Calcium Carbonate and Calcium Citrate after Roux-en-Y Gastric Bypass

PubMed Central

Tondapu, P.; Provost, D.; Adams-Huet, B.; Sims, T.; Chang, C.; Sakhaee, K.

2015-01-01

Introduction Roux-en-Y gastric bypass (RYGB) restricts food intake. Consequently, patients consume less calcium. In addition, food no longer passes through the duodenum, the main site of calcium absorption. Therefore, calcium absorption is significantly impaired. The goal of this study is to compare two common calcium supplements in gastric bypass patients. Method Nineteen patients were enrolled in a randomized, double-blinded, crossover study comparing the absorption of calcium from calcium carbonate and calcium citrate salts. Serum and urine calcium levels were assessed for peak values (Cmax) and cumulative calcium increment (area under the curve [AUC]). Serum PTH was assessed for minimum values (PTHmin) and cumulative PTH decrement (AUC). Statistical analysis was performed using a repeated analysis of variance model. Results Eighteen subjects completed the study. Calcium citrate resulted in a significantly higher serum Cmax (9.4+0.4 mg/dl vs. 9.2+0.3 mg/dl, p=0.02) and serum AUC (55+2 mg/dl vs. 54+2 mg/dl, p=0.02). Calcium citrate resulted in a significantly lower PTHmin (24+11 pg/ml vs. 30+13 pg/ml, p=0.01) and a higher AUC (−32+51 pg/ml vs. −3+56 pg/ml, p=0.04). There was a non-significant trend for higher urinary AUC in the calcium citrate group (76.13+36.39 mg/6 h vs. 66.04+40.82, p=0.17). Conclusion Calcium citrate has superior bioavailability than calcium carbonate in RYGB patients. PMID:19437082

Calcium absorption is not increased by caseinophosphopeptides.

PubMed

Teucher, Birgit; Majsak-Newman, Gosia; Dainty, Jack R; McDonagh, David; FitzGerald, Richard J; Fairweather-Tait, Susan J

2006-07-01

One of the suggested health benefits of caseinophosphopeptides (CPPs) is their ability to enhance calcium absorption. This possibility is based on the assumption that they resist proteolysis in the upper gastrointestinal tract and maintain calcium in a soluble form at alkaline pH in the distal ileum. The effects of CPP-enriched preparations (containing candidate functional food ingredients) on calcium absorption from a calcium lactate drink were tested. A randomized crossover trial was undertaken in 15 adults in whom we measured the absorption of calcium from a calcium lactate drink (drink A: 400 mg Ca as lactate) and 2 preparations enriched with forms of CPP (1.7 g each; drinks B and C). Both drinks B and C contained 400 mg Ca as calcium lactate plus approximately 100 mg CPP-derived calcium). Each volunteer received the 3 drinks in random order. Absorption was measured by the dual-label calcium stable-isotope technique. The quantity of calcium absorbed was significantly lower from drink A (103 mg) than from drink B (117 mg; P = 0.012) or drink C (121 mg; P = 0.002), which indicated a positive effect of the CPPs. However, because the CPP preparations contributed additional calcium besides that found in the calcium lactate (drink A), fractional absorption of calcium from drink B (23%) was slightly but significantly (P = 0.015) lower than that from drink A (26%). The differences in calcium absorption are unlikely to have any biological significance. CPPs are unsuitable as candidate ingredients for functional foods that are designed to deliver improved calcium nutrition.

Calcium alloy as active material in secondary electrochemical cell

DOEpatents

Roche, Michael F.; Preto, Sandra K.; Martin, Allan E.

1976-01-01

Calcium alloys such as calcium-aluminum and calcium-silicon, are employed as active material within a rechargeable negative electrode of an electrochemical cell. Such cells can use a molten salt electrolyte including calcium ions and a positive electrode having sulfur, sulfides, or oxides as active material. The calcium alloy is selected to prevent formation of molten calcium alloys resulting from reaction with the selected molten electrolytic salt at the cell operating temperatures.

21 CFR 184.1187 - Calcium alginate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Calcium alginate is prepared by...

21 CFR 184.1191 - Calcium carbonate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium carbonate. 184.1191 Section 184.1191 Food... GRAS § 184.1191 Calcium carbonate. (a) Calcium carbonate (CaCO3, CAS Reg. No. 471-34-1) is prepared by... of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation of...

Monitoring the progression of calcium and protein solubilisation as affected by calcium chelators during small-scale manufacture of casein-based food matrices.

PubMed

McIntyre, Irene; O'Sullivan, Michael; O'Riordan, Dolores

2017-12-15

Calcium and protein solubilisation during small-scale manufacture of semi-solid casein-based food matrices was investigated and found to be very different in the presence or absence of calcium chelating salts. Calcium concentrations in the dispersed phase increased and calcium-ion activity (A Ca ++ ) decreased during manufacture of the matrices containing calcium chelating salts; with ∼23% of total calcium solubilised by the end of manufacture. In the absence of calcium chelating salts, these concentrations were significantly lower at equivalent processing times and remained unchanged as did A Ca ++ , throughout manufacture. The protein content of the dispersed phase was low (≤3% of total protein), but was significantly higher for matrices containing calcium chelating salts. This study elucidates the critical role of calcium chelating salts in modulating casein hydration and dispersion and gives an indication of the levels of soluble calcium and protein required to allow matrix formation during manufacture of casein-based food structures e.g. processed and analogue cheese. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Hepatitis B Virus X Protein Elevates Cytosolic Calcium Signals by Modulating Mitochondrial Calcium Uptake

PubMed Central

Yang, Bei

2012-01-01

Chronic hepatitis B virus (HBV) infections are associated with the development of hepatocellular carcinoma (HCC). The HBV X protein (HBx) is thought to play an important role in the development of HBV-associated HCC. One fundamental HBx function is elevation of cytosolic calcium signals; this HBx activity has been linked to HBx stimulation of cell proliferation and transcription pathways, as well as HBV replication. Exactly how HBx elevates cytosolic calcium signals is not clear. The studies described here show that HBx stimulates calcium entry into cells, resulting in an increased plateau level of inositol 1,4,5-triphosphate (IP3)-linked calcium signals. This increased calcium plateau can be inhibited by blocking mitochondrial calcium uptake and store-operated calcium entry (SOCE). Blocking SOCE also reduced HBV replication. Finally, these studies also demonstrate that there is increased mitochondrial calcium uptake in HBx-expressing cells. Cumulatively, these studies suggest that HBx can increase mitochondrial calcium uptake and promote increased SOCE to sustain higher cytosolic calcium and stimulate HBV replication. PMID:22031934

Visualisation of an nsPEF induced calcium wave using the genetically encoded calcium indicator GCaMP in U87 human glioblastoma cells.

PubMed

Carr, Lynn; Bardet, Sylvia M; Arnaud-Cormos, Delia; Leveque, Philippe; O'Connor, Rodney P

2018-02-01

Cytosolic, synthetic chemical calcium indicators are typically used to visualise the rapid increase in intracellular calcium ion concentration that follows nanosecond pulsed electric field (nsPEF) application. This study looks at the application of genetically encoded calcium indicators (GECIs) to investigate the spatiotemporal nature of nsPEF-induced calcium signals using fluorescent live cell imaging. Calcium responses to 44kV/cm, 10ns pulses were observed in U87-MG cells expressing either a plasma membrane targeted GECI (GCaMP5-G), or one cytosolically expressed (GCaMP6-S), and compared to the response of cells loaded with cytosolic or plasma membrane targeted chemical calcium indicators. Application of 100 pulses, to cells containing plasma membrane targeted indicators, revealed a wave of calcium across the cell initiating at the cathode side. A similar spatial wave was not observed with cytosolic indicators with mobile calcium buffering properties. The speed of the wave was related to pulse application frequency and it was not propagated by calcium induced calcium release. Copyright © 2017 Elsevier B.V. All rights reserved.

Reversible loss of gravitropic sensitivity in maize roots after tip application of calcium chelators

NASA Technical Reports Server (NTRS)

Lee, J. S.; Mulkey, T. J.; Evans, M. L.

1983-01-01

The application of calcium chelating agents (EDTA or EGTA) to the tips of maize roots caused a loss of gravitropic sensitivity. When the chelator was replaced with calcium chloride, gravitropic sensitivity was restored. Asymmetric application of calcium chloride near the tip of a vertical root caused curvature toward the calcium source. When the calcium was applied to the upper surface of the tip of a root oriented horizontally, the root curved upward even though control roots exhibited strong downward curvature. Application of calcium chloride to the tips of decapped roots, which are known to be gravitropically insensitive, did not restore gravitropic sensitivity. However, asymmetric application of calcium chloride near the tips of decapped roots caused curvature toward the calcium source. Calcium may play a key role in linking gravity detection to gravitropic curvature in roots.

Calcium isotope fractionation between soft and mineralized tissues as a monitor of calcium use in vertebrates.

PubMed

Skulan, J; DePaolo, D J

1999-11-23

Calcium from bone and shell is isotopically lighter than calcium of soft tissue from the same organism and isotopically lighter than source (dietary) calcium. When measured as the (44)Ca/(40)Ca isotopic ratio, the total range of variation observed is 5.5 per thousand, and as much as 4 per thousand variation is found in a single organism. The observed intraorganismal calcium isotopic variations and the isotopic differences between tissues and diet indicate that isotopic fractionation occurs mainly as a result of mineralization. Soft tissue calcium becomes heavier or lighter than source calcium during periods when there is net gain or loss of mineral mass, respectively. These results suggest that variations of natural calcium isotope ratios in tissues may be useful for assessing the calcium and mineral balance of organisms without introducing isotopic tracers.

Calcium isotope fractionation between soft and mineralized tissues as a monitor of calcium use in vertebrates

PubMed Central

Skulan, Joseph; DePaolo, Donald J.

1999-01-01

Calcium from bone and shell is isotopically lighter than calcium of soft tissue from the same organism and isotopically lighter than source (dietary) calcium. When measured as the 44Ca/40Ca isotopic ratio, the total range of variation observed is 5.5‰, and as much as 4‰ variation is found in a single organism. The observed intraorganismal calcium isotopic variations and the isotopic differences between tissues and diet indicate that isotopic fractionation occurs mainly as a result of mineralization. Soft tissue calcium becomes heavier or lighter than source calcium during periods when there is net gain or loss of mineral mass, respectively. These results suggest that variations of natural calcium isotope ratios in tissues may be useful for assessing the calcium and mineral balance of organisms without introducing isotopic tracers. PMID:10570137

Two-pore channels: Regulation by NAADP and customized roles in triggering calcium signals

PubMed Central

Patel, Sandip; Marchant, Jonathan; Brailoiu, Eugen

2010-01-01

NAADP is a potent regulator of cytosolic calcium levels. Much evidence suggests that NAADP activates a novel channel located on an acidic (lysosomal-like) calcium store, the mobilisation of which results in further calcium release from the endoplasmic reticulum. Here, we discuss the recent identification of a family of poorly characterized ion channels (the two-pore channels) as endo-lysosomal NAADP receptors. The generation of calcium signals by these channels is likened to those evoked by depolarisation during excitation-contraction coupling in muscle. We discuss the idea that two pore-channels can mediate a trigger release of calcium which is then amplified by calcium-induced calcium release from the endoplasmic reticulum. This is similar to the activation of voltage-sensitive calcium channels and subsequent mobilisation of sarcoplasmic reticulum calcium stores in cardiac tissue. We suggest that two-pore channels may physically interact with ryanodine receptors to account for more direct release of calcium from the endoplasmic reticulum in analogy with the conformational coupling of voltage-sensitive calcium channels and ryanodine receptors in skeletal muscle. Interaction of two-pore channels with other calcium release channels likely occurs between stores “trans-chatter” and possibly within the same store “cis-chatter”. We also speculate that trafficking of two-pore channels through the endolysosomal system facilitates interactions with calcium entry channels. Strategic placing of two-pore channels thus provides a versatile means of generating spatiotemporally complex cellular calcium signals. PMID:20621760

Barriers to supplemental calcium use among women in suburban family practice: a report from the Cleveland Clinic Ambulatory Research Network (CleAR-eN).

PubMed

Tyler, Carl V; Werner, James J; Panaite, Vanessa; Snyder, Sandra M; Ford, Donald B; Conway, Jessica L; Young, Christopher W; Powell, Brenda L; Smolak, Michael J; Zyzanski, Stephen J

2008-01-01

The majority of adult women in the United States fail to meet daily calcium intake recommendations. This study was undertaken to (1) identify predictors of calcium supplement use versus non-use, (2) understand barriers to calcium supplementation, and (3) determine the potential impact of physician recommendation on calcium supplement use. Surveys were self-administered by 185 women, ages 20 to 64, presenting consecutively for care at 6 suburban community-based family medicine practices within the Cleveland Clinic Ambulatory Research Network (CleAR-eN). We compared demographic characteristics, health beliefs, and health behaviors of those women who reported never using calcium supplements with those who presently took calcium supplements. Women who never took calcium were also queried about reasons for non-use and whether physician recommendation would influence their adoption of calcium supplementation. Multivitamin use, self-perceived risk of osteoporosis, and age were independent predictors of calcium supplement use. Leading barriers for never-users were lack of knowledge about the need/importance of increasing calcium intake, lack of motivation to start supplements, and the belief that their dietary calcium intake alone was sufficient. Ninety-six percent of never-users reported that they would consider taking a calcium supplement if recommended by their physician. Many patient-identified barriers to calcium supplementation seem amenable to focused and brief office-based interventions that could increase the number of women meeting calcium intake guidelines.

Calcium content of different compositions of gallstones and pathogenesis of calcium carbonate gallstones.

PubMed

Yu, Ji-Kuen; Pan, Huichin; Huang, Shing-Moo; Huang, Nan-Lan; Yao, Chung-Chin; Hsiao, Kuang-Ming; Wu, Chew-Wun

2013-01-01

Our aim was to investigate the calcium content of different gallstone compositions and the pathogenic mechanisms of calcium carbonate gallstones. Between August 2001 and July 2007, gallstones from 481 patients, including 68 calcium carbonate gallstones, were analyzed for total calcium content. Gallbladder bile samples from 33 cases and six controls were analyzed for pH, carbonate anion level, free-ionized calcium concentration and saturation index for calcium carbonate. Total calcium content averaged 75.6 %, 11.8 %, and 4.2 % for calcium carbonate, calcium bilirubinate and cholesterol gallstones. In 29.4 % of patients, chronic and/or intermittent cystic duct obstructions were caused by polypoid lesions in the neck region and 70.6 % were caused by stones. A total of 82 % of patients had chronic low-grade inflammation of the gallbladder wall and 18.0 % had acute inflammatory exacerbations. In the bile, we found the mean pH, mean carbonate anion, free-ionized calcium concentrations, and mean saturation index for calcium carbonate to be elevated in comparison to controls. From our study, we found chronic and/or intermittent cystic duct obstructions and low-grade GB wall inflammation lead to GB epithelium hydrogen secretion dysfunction. Increased calcium ion efflux into the GB lumen combined with increased carbonate anion presence increases SI_CaCO(3) from 1 to 22.4. Thus, in an alkaline milieu with pH 7.8, calcium carbonate begins to aggregate and precipitate. Copyright © 2012. Published by Elsevier B.V.

[The dynamics of calcium distribution in stigma and style of lettuce (Lactuca sativa L.) before and after pollination].

PubMed

Qiu, Yi Lan; Liu, Ru Shi; Xie, Chao Tian; Yang, Yan Hong; Gu, Li; Tian, Hui Qiao

2005-08-01

Potassium antimonite was used to deposit calcium in the stigma and style of lettuce (Lactuca sativa L.) before and after pollination. The stigma of lettuce is two splits. Abundant calcium granules are displayed in the wall of papillae on the receptive surface of stigma before and after pollination, which may facilitate pollen germination. However, a few calcium granules in the wall of epidermis cell on no-receptive surface. Calcium distribution in style presents a gradient in transmitting tissue and parenchyma cells from the top to the base of the style before pollination. After pollination, calcium in transmitting tissue distinctly increased and its gradient distribution became more evident. Pollen tubes grow in the intercellular gaps of transmitting tissue. When pollen tubes grew into transmitting tissue, calcium granules in parenchyma around transmitting tissue decreased, suggesting a calcium movement was controlled by pollen tubes. The calcium gradient distribution also appeared in the trachea of vascular bundle of style. In general, calcium in style displays a feature of time-special distribution: transmitting tissue doesn't need much more calcium that is only stored in the parenchyma before pollination. However, calcium in parenchyma cells may be transported to transmitting tissue and make the latter contain more calcium to form an evident calcium gradient and meet the requirement of pollen tubes directionally growing after pollination. This is the second sample of calcium gradient existing in style, which was found by using potassium antimonite method.

Role of calcium in growth inhibition induced by a novel cell surface sialoglycopeptide

NASA Technical Reports Server (NTRS)

Betz, N. A.; Westhoff, B. A.; Johnson, T. C.; Spooner, B. S. (Principal Investigator)

1995-01-01

Our laboratory has purified an 18 kDa cell surface sialoglycopeptide growth inhibitor (CeReS-18) from intact bovine cerebral cortex cells. Evidence presented here demonstrates that sensitivity to CeReS-18-induced growth inhibition in BALB-c 3T3 cells is influenced by calcium, such that a decrease in the calcium concentration in the growth medium results in an increase in sensitivity to CeReS-18. Calcium did not alter CeReS-18 binding to its cell surface receptor and CeReS-18 does not bind calcium directly. Addition of calcium, but not magnesium, to CeReS-18-inhibited 3T3 cells results in reentry into the cell cycle. A greater than 3-hour exposure to increased calcium is required for escape from CeReS-18-induced growth inhibition. The calcium ionophore ionomycin could partially mimic the effect of increasing extracellular calcium, but thapsigargin was ineffective in inducing escape from growth inhibition. Increasing extracellular calcium 10-fold resulted in an approximately 7-fold increase in total cell-associated 45Ca+2, while free intracellular calcium only increased approximately 30%. However, addition of CeReS-18 did not affect total cell-associated calcium or the increase in total cell-associated calcium observed with an increase in extracellular calcium. Serum addition induced mobilization of intracellular calcium and influx across the plasma membrane in 3T3 cells, and pretreatment of 3T3 cells with CeReS-18 appeared to inhibit these calcium mobilization events. These results suggest that a calcium-sensitive step exists in the recovery from CeReS-18-induced growth inhibition. CeReS-18 may inhibit cell proliferation through a novel mechanism involving altering the intracellular calcium mobilization/regulation necessary for cell cycle progression.

Biotic Nitrogen Enrichment Regulates Calcium Sources to Forests

NASA Astrophysics Data System (ADS)

Pett-Ridge, J. C.; Perakis, S. S.; Hynicka, J. D.

2015-12-01

Calcium is an essential nutrient in forest ecosystems that is susceptible to leaching loss and depletion. Calcium depletion can affect plant and animal productivity, soil acid buffering capacity, and fluxes of carbon and water. Excess nitrogen supply and associated soil acidification are often implicated in short-term calcium loss from soils, but the long-term role of nitrogen enrichment on calcium sources and resupply is unknown. Here we use strontium isotopes (87Sr/86Sr) as a proxy for calcium to investigate how soil nitrogen enrichment from biological nitrogen fixation interacts with bedrock calcium to regulate both short-term available supplies and the long-term sources of calcium in montane conifer forests. Our study examines 22 sites in western Oregon, spanning a 20-fold range of bedrock calcium on sedimentary and basaltic lithologies. In contrast to previous studies emphasizing abiotic control of weathering as a determinant of long-term ecosystem calcium dynamics and sources (via bedrock fertility, climate, or topographic/tectonic controls) we find instead that that biotic nitrogen enrichment of soil can strongly regulate calcium sources and supplies in forest ecosystems. For forests on calcium-rich basaltic bedrock, increasing nitrogen enrichment causes calcium sources to shift from rock-weathering to atmospheric dominance, with minimal influence from other major soil forming factors, despite regionally high rates of tectonic uplift and erosion that can rejuvenate weathering supply of soil minerals. For forests on calcium-poor sedimentary bedrock, we find that atmospheric inputs dominate regardless of degree of nitrogen enrichment. Short-term measures of soil and ecosystem calcium fertility are decoupled from calcium source sustainability, with fundamental implications for understanding nitrogen impacts, both in natural ecosystems and in the context of global change. Our finding that long-term nitrogen enrichment increases forest reliance on atmospheric calcium helps explain reports of greater ecological calcium limitation in an increasingly nitrogen-rich world.

Evidence for a Regulatory Role of Calcium in Gravitropism

NASA Technical Reports Server (NTRS)

Roux, S. J.

1983-01-01

Experiments conducted to determine the cellular basis of gravitropism, the phenomenon of calcium migration following gravitropic stimulation, and the preferential accumulation of calcium in cells are described. Results of autoradiographic studies of cross sections of oat, and the pryoantimony precipitation of calcium in situ are discussed. It was found that the movement of calcium during gravimetric stimulation is a redistribution of calcium from the vacuolar regions into the cells walls. This movement requires precipitation of a calcium ATPase. The control of calcium ATPase by calmodulin and whether chlorpromazine is binding to calmodulin in plants are considered.

Dietary Calcium Intake, Serum Calcium Level, and their Association with Preeclampsia in Rural North India

PubMed Central

Gupta, Anant; Kant, Shashi; Pandav, Chandrakant S.; Gupta, Sanjeev K.; Rai, Sanjay K.; Misra, Puneet

2016-01-01

Background: Preeclampsia in pregnancy has been shown to be associated with low serum calcium level. Though the evidence is abundant, it is equivocal. Objectives: The study aimed to estimate the dietary calcium intake and serum calcium status among pregnant women, and to document the association of the dietary calcium intake and serum calcium status with incidence of preeclampsia in the 3rd trimester of pregnancy. Materials and Methods: A community-based cross-sectional study was conducted in the Health and Demographic Surveillance System (HDSS) site, Ballabgarh, Haryana, India. All pregnant women between 28 weeks and 36 weeks of gestation were interviewed. A semi-structured interview schedule and a 24-h dietary recall questionnaire were administered to assess the dietary calcium intake. AutoAnalyser (Biolis 24i) was used for measuring serum calcium. Results: We enrolled 217 pregnant women. The mean [standard deviation (SD)] dietary calcium intake was 858 (377) mg/day. The mean (SD) serum calcium level was 9.6 mg/dL (0.56). Incidence of preeclampsia was 13.4%. Preeclampsia was not associated with hypocalcemia [odds ratio (OR) = 1.2 95% confidence interval (CI); 0.27-3.98]. Conclusion: The majority of pregnant women had inadequate dietary calcium intake. The prevalence of hypocalcemia was low. Low serum calcium level was not associated with preeclampsia. Calcium supplementation may not reduce preeclampsia in this population. PMID:27385877

Teaching Calcium-Induced Calcium Release in Cardiomyocytes Using a Classic Paper by Fabiato

ERIC Educational Resources Information Center

Liang, Willmann

2008-01-01

This teaching paper utilizes the materials presented by Dr. Fabiato in his review article entitled "Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum." In the review, supporting evidence of calcium-induced calcium release (CICR) is presented. Data concerning potential objections to the CICR theory are discussed as well. In…

Factors to consider in the selection of a calcium supplement.

PubMed Central

Shangraw, R F

1989-01-01

Calcium supplements are widely used, yet many questions remain as to the absorption of various calcium salts. Because the solubility of many calcium salts is dependent upon pH, the type of salt used, the condition of the patient, and the time of administration should be considered. Studies show that many calcium supplements on the market today do not meet standards of quality established in the "U.S. Pharmacopeia" (USP). Consumers must be discerning about the products they purchase. Calcium supplements should be taken with meals to ensure solubility. Calcium carbonate, and particularly tribasic calcium phosphate tablets, are not recommended for patients with achlorhydria. Calcium tablets, like almost all drugs, should be taken with 8 ounces of water or other liquid. PMID:2517700

Dependency of Calcium Alternans on Ryanodine Receptor Refractoriness

PubMed Central

Alvarez-Lacalle, Enric; Cantalapiedra, Inma R.; Peñaranda, Angelina; Cinca, Juan; Hove-Madsen, Leif; Echebarria, Blas

2013-01-01

Background Rapid pacing rates induce alternations in the cytosolic calcium concentration caused by fluctuations in calcium released from the sarcoplasmic reticulum (SR). However, the relationship between calcium alternans and refractoriness of the SR calcium release channel (RyR2) remains elusive. Methodology/Principal Findings To investigate how ryanodine receptor (RyR2) refractoriness modulates calcium handling on a beat-to-beat basis using a numerical rabbit cardiomyocyte model. We used a mathematical rabbit cardiomyocyte model to study the beat-to-beat calcium response as a function of RyR2 activation and inactivation. Bi-dimensional maps were constructed depicting the beat-to-beat response. When alternans was observed, a novel numerical clamping protocol was used to determine whether alternans was caused by oscillations in SR calcium loading or by RyR2 refractoriness. Using this protocol, we identified regions of RyR2 gating parameters where SR calcium loading or RyR2 refractoriness underlie the induction of calcium alternans, and we found that at the onset of alternans both mechanisms contribute. At low inactivation rates of the RyR2, calcium alternans was caused by alternation in SR calcium loading, while at low activation rates it was caused by alternation in the level of available RyR2s. Conclusions/Significance We have mapped cardiomyocyte beat-to-beat responses as a function of RyR2 activation and inactivation, identifying domains where SR calcium load or RyR2 refractoriness underlie the induction of calcium alternans. A corollary of this work is that RyR2 refractoriness due to slow recovery from inactivation can be the cause of calcium alternans even when alternation in SR calcium load is present. PMID:23390511

Serum calcium and incident diabetes: an observational study and meta-analysis.

PubMed

Sing, C W; Cheng, V K F; Ho, D K C; Kung, A W C; Cheung, B M Y; Wong, I C K; Tan, K C B; Salas-Salvadó, J; Becerra-Tomas, N; Cheung, C L

2016-05-01

The study aimed to prospectively evaluate if serum calcium is related to diabetes incidence in Hong Kong Chinese. The results showed that serum calcium has a significant association with increased risk of diabetes. The result of meta-analysis reinforced our findings. This study aimed to evaluate the association of serum calcium, including serum total calcium and albumin-corrected calcium, with incident diabetes in Hong Kong Chinese. We conducted a retrospective cohort study in 6096 participants aged 20 or above and free of diabetes at baseline. Serum calcium was measured at baseline. Incident diabetes was determined from several electronic databases. We also searched relevant databases for studies on serum calcium and incident diabetes and conducted a meta-analysis using fixed-effect modeling. During 59,130.9 person-years of follow-up, 631 participants developed diabetes. Serum total calcium and albumin-corrected calcium were associated with incident diabetes in the unadjusted model. After adjusting for demographic and clinical variables, the association remained significant only for serum total calcium (hazard ratio (HR), 1.32 (95 % confidence interval (CI), 1.02-1.70), highest vs. lowest quartile). In a meta-analysis of four studies including the current study, both serum total calcium (pooled risk ratio (RR), 1.38 (95 % CI, 1.15-1.65); I (2) = 5 %, comparing extreme quantiles) and albumin-corrected calcium (pooled RR, 1.29 (95 % CI, 1.03-1.61); I (2) = 0 %, comparing extreme quantiles) were associated with incident diabetes. Penalized regression splines showed that the association of incident diabetes with serum total calcium and albumin-correlated calcium was non-linear and linear, respectively. Elevated serum calcium concentration is associated with incident diabetes. The mechanism underlying this association warrants further investigation.

A comparative study of calcium absorption following a single serving administration of calcium carbonate powder versus calcium citrate tablets in healthy premenopausal women

PubMed Central

Wang, Haiyuan; Bua, Peter; Capodice, Jillian

2014-01-01

Background Calcium is an essential mineral often taken as a daily, long-term nutritional supplement. Data suggests that once-daily dosing is important with regard to long-term compliance of both drugs and nutritional supplements. Objective This study was undertaken to compare the bioavailability of a single serving of two calcium supplements in healthy, premenopausal women. Design A two-period, crossover bioavailability study of a single serving of calcium citrate tablets (two tablets=500 mg calcium) versus a single serving of calcium carbonate powder (one packet of powder=1,000 mg calcium) was performed in healthy women aged between 25 and 45. All subjects were on a calcium-restricted diet 7 days prior to testing and fasted for 12 h before being evaluated at 0, 1, 2, and 4 h after oral administration of the test agents. Blood measurements for total and ionized calcium and parathyroid hormone were performed and adverse events were monitored. Results Twenty-three women were evaluable with a mean age of 33.2±8.71. Results showed that administration of a single serving of a calcium carbonate powder resulted in greater absorption in total and ionized calcium versus a single serving of calcium citrate tablets at 4 h (4.25±0.21 vs. 4.16±0.16, p=0.001). There were minimal side effects and no reported serious adverse events. Conclusions This study shows that a single serving of a calcium carbonate powder is more bioavailable than a single serving of calcium citrate tablets. This may be beneficial for long-term compliance. PMID:24772062

Fast calcium transients translate the distribution and conduction of neural activity in different regions of a single sensory neuron.

PubMed

Purali, Nuhan

2017-09-01

In the present study, cytosolic calcium concentration changes were recorded in response to various forms of excitations, using the fluorescent calcium indicator dye OG-BAPTA1 together with the current or voltage clamp methods in stretch receptor neurons of crayfish. A single action potential evoked a rise in the resting calcium level in the axon and axonal hillock, whereas an impulse train or a large saturating current injection would be required to evoke an equivalent response in the dendrite region. Under voltage clamp conditions, amplitude differences between axon and dendrite responses vanished completely. The fast activation time and the modulation of the response by extracellular calcium concentration changes indicated that the evoked calcium transients might be mediated by calcium entry into the cytosol through a voltage-gated calcium channel. The decay of the responses was slow and sensitive to extracellular sodium and calcium concentrations as well as exposure to 1-10 mM NiCl 2 and 10-500 µM lanthanum. Thus, a sodium calcium exchanger and a calcium ATPase might be responsible for calcium extrusion from the cytosol. Present results indicate that the calcium indicator OG-BAPTA1 might be an efficient but indirect way of monitoring regional membrane potential differences in a single neuron.

The effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate bone cement

NASA Astrophysics Data System (ADS)

Razali, N. N.; Sukardi, M. A.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.

2018-01-01

The objective of this study is to determine the effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate cement (CPC) for bone filling applications. Hydroxyapatite powder was synthesized via hydrothermal method using calcium oxide, CaO and ammonium dihydrogen phosphate, NH4H2PO4 as the calcium and phosphorus precursors respectively. The effects of calcium excess were evaluated by varying the CaO content at 0, 5 and 15 mole %. The precursors were then refluxed in distilled water at 90-100°C and dried overnight until the calcium phosphate powder was formed. CPC was then produced by mixing the synthesized powder with distilled water at the powder-to-liquid (P/L) ratio of 1.5. The result from the morphological properties of CPC shows the increase in agglomeration and particles size with 5 mole % of calcium excess but decreased with 15 mole % of calcium excess in CPC. This result was in agreement with the compressive strength result where the CPC increased its strength with 5 mole % of calcium excess but reduced with 15 mole % of calcium excess. The excess in calcium precursor also significantly improved the setting time but reduced the injectability of CPC.

Antenatal calcium intake in Malaysia.

PubMed

Mahdy, Zaleha Abdullah; Basri, Hashimah; Md Isa, Zaleha; Ahmad, Shuhaila; Shamsuddin, Khadijah; Mohd Amin, Rahmah

2014-04-01

To determine the adequacy of antenatal calcium intake in Malaysia, and the influencing factors. A cross-sectional study was conducted among postnatal women who delivered in two tertiary hospitals. Data were collected from antenatal cards, hospital documents and diet recall on daily milk and calcium intake during pregnancy. SPSS version 19.0 was used for statistical analyses. A total of 150 women were studied. The total daily calcium intake was 834 ± 43 mg (mean ± standard error of the mean), but the calcium intake distribution curve was skewed to the right with a median intake of 725 mg daily. When calcium intake from milk and calcium supplements was excluded, the daily dietary calcium intake was only 478 ± 25 mg. Even with inclusion of milk and calcium supplements, more than a third (n=55 or 36.7%) of the women consumed less than 600 mg calcium in their daily diet. The adequacy of daily calcium intake was not influenced by maternal age, ethnicity, income or maternal job or educational status as well as parity. The daily dietary calcium intake of the Malaysian antenatal population is far from adequate without the addition of calcium supplements and milk. © 2013 The Authors. Journal of Obstetrics and Gynaecology Research © 2013 Japan Society of Obstetrics and Gynecology.

Calcium Bioavailability from Mineral Waters with Different Mineralization in Comparison to Milk and a Supplement.

PubMed

Greupner, Theresa; Schneider, Inga; Hahn, Andreas

2017-07-01

The aim of the present study was to compare the bioavailability of calcium from 3 mineral waters with different concentrations of minerals with that of milk and a calcium supplement. A single-center, randomized controlled trial with a crossover design with 21 healthy men and women was conducted at the Institute of Food Science and Human Nutrition, Leibniz University Hannover. The participants consumed the 5 test products providing 300 mg of calcium each on 5 examination days with 1-week wash-out phases in between. Primary outcome variables were the area under the curve of serum calcium levels for 10-hour (AUC 0-10h ) and 24-hour urinary calcium excretion. In all groups, no significant differences in the AUC 0-10h of serum calcium levels as well as in the 24-hour urinary calcium excretion were observed. Likewise, mean changes in serum phosphate and urinary phosphate, as well as serum parathormone, showed no differences between the groups. Given an equivalent bioavailability of calcium in all test products, neither a high concentration of SO 4 2- or of HCO 3 influenced the bioavailability of calcium. Accordingly, the use of mineral water with high concentrations of calcium constitutes a calorie-free calcium source that can improve calcium supply.

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

Protection of Dentate Hilar Cells from Prolonged Stimulation by Intracellular Calcium Chelation

NASA Astrophysics Data System (ADS)

Scharfman, Helen E.; Schwartzkroin, Philip A.

1989-10-01

Prolonged afferent stimulation of the rat dentate gyrus in vivo leads to degeneration only of those cells that lack immunoreactivity for the calcium binding proteins parvalbumin and calbindin. In order to test the hypothesis that calcium binding proteins protect against the effects of prolonged stimulation, intracellular recordings were made in hippocampal slices from cells that lack immunoreactivity for calcium binding proteins. Calcium binding protein--negative cells showed electrophysiological signs of deterioration during prolonged stimulation; cells containing calcium binding protein did not. When neurons without calcium binding proteins were impaled with microelectrodes containing the calcium chelator BAPTA, and BAPTA was allowed to diffuse into the cells, these cells showed no deterioration. These results indicate that, in a complex tissue of the central nervous system, an activity-induced increase in intracellular calcium can trigger processes leading to cell deterioration, and that increasing the calcium binding capacity of a cell decreases its vulnerability to damage.

Lack of voltage-dependent calcium channel opening during the calcium influx induced by progesterone in human sperm. Effect of calcium channel deactivation and inactivation.

PubMed

Guzmán-Grenfell, Alberto Martín; González-Martínez, Marco T

2004-01-01

Progesterone induces calcium influx and acrosomal exocytosis in human sperm. Pharmacologic evidence suggests that voltage-dependent calcium channels (VDCCs) are involved. In this study, membrane potential (Vm) and intracellular calcium concentration ([Ca(2+)](i)) were monitored simultaneously to assess the effect of VDCC gating on the calcium influx triggered by progesterone. Holding the Vm to values that maintained VDCCs in a deactivated (-71 mV) closed state inhibited the calcium influx induced by progesterone by approximately 40%. At this Vm, the acrosomal reaction induced by progesterone, but not by A23187, was inhibited. However, when the Vm was held at -15 mV (which maintains VDCCs in an inactivated closed state), the progesterone-induced calcium influx was stimulated. Furthermore, the progesterone and voltage-dependent calcium influxes were additive. These findings indicate that progesterone does not produce VDCC gating in human sperm.

[Calcium and magnesium concentrations in "Healthy" and lithiasic human kidney (author's transl)].

PubMed

Terhorst, B; Stoeppler, M

1976-07-01

Calcium and magnesium levels in the cortex, medulla, and papilla of human kidney from 32 so-called healthy patients and from eleven patients with calcium-oxalate lithiasis were determined by atom-absorption spectralphotometry. A positive calcium gradient with the highest calcium concentration in the papilla was found in all kidneys. Compared to the control group, that calcium concentration in the lithiasic kidneys was reduced by 50% in the papilla, but in the cortex and medulla, the levels were the same. A relative depletion of calcium in the papilla in hypercalciuria goes against the theory that the papilla is the main center of development of calcium-containing stones. The magnesium concentration was practically the same in cortex, medulla, and papilla, and no significant difference was found between lithiasic and healthy kidneys. These findings underline the central role of calcium in the genesis of calcium-containing stones.

Calcium bodies of Titanethes albus (Crustacea: Isopoda): molt-related structural dynamics and calcified matrix-associated bacteria.

PubMed

Vittori, Miloš; Kostanjšek, Rok; Znidaršič, Nada; Zagar, Kristina; Ceh, Miran; Strus, Jasna

2012-10-01

Crustaceans form a variety of calcium deposits in which they store calcium necessary for the mineralization of their exoskeletons. Calcium bodies, organs containing large amounts of calcium, have been reported in some terrestrial isopod crustaceans, but have not yet been extensively studied. We analyzed the architecture of these organs during the molt cycle in the isopod Titanethes albus. Two pairs of calcium bodies are positioned ventrolaterally in posterior pereonites of T. albus. Individual organs are epithelial sacs that contain material arranged in concentric layers delimited by thin laminae. As demonstrated by electron microscopy and fluorescence in situ hybridization, abundant bacteria are present within the calcium bodies. Regardless of the molt cycle stage, crystalline concretions are present in the central areas of the calcium bodies. Energy dispersive X-ray spectrometry of the concretions demonstrated that they are composed predominantly of calcium and phosphorus and selected area electron diffraction indicated the presence of hydroxyapatite. In molting animals, a glassy layer of mineralized matrix is formed between the envelope and the outermost lamina of the calcium body. This layer consists of an amorphous calcium mineral which contains less phosphorus than the central concretions and is resorbed after molt. Since changes in the mineralized matrix are synchronized with the molt cycle, the calcium bodies likely function as a storage compartment that complements sternal deposits as a source of calcium for the mineralization of the exoskeleton. Bacteria associated with the mineralized matrix of calcium bodies are evidently involved in calcium dynamics. Copyright © 2012 Elsevier Inc. All rights reserved.

Exopolysaccharides regulate calcium flow in cariogenic biofilms

PubMed Central

Varenganayil, Muth M.; Decho, Alan W.

2017-01-01

Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS) provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya’s agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC) by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR) spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC). Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries. PMID:29023506

Ionotropic and Metabotropic Mechanisms of Allosteric Modulation of α7 Nicotinic Receptor Intracellular Calcium.

PubMed

King, Justin R; Ullah, Aman; Bak, Ellen; Jafri, M Saleet; Kabbani, Nadine

2018-06-01

The pharmacological targeting of the α 7 nicotinic acetylcholine receptor ( α 7) is a promising strategy in the development of new drugs for neurologic diseases. Because α 7 receptors regulate cellular calcium, we investigated how the prototypical type II-positive allosteric modulator PNU120596 affects α 7-mediated calcium signaling. Live imaging experiments show that PNU120596 augments ryanodine receptor-driven calcium-induced calcium release (CICR), inositol-induced calcium release (IICR), and phospholipase C activation by the α 7 receptor. Both influx of calcium through the α 7 nicotinic acetylcholine receptor (nAChR) channel as well as the binding of intracellular G proteins were involved in the effect of PNU120596 on intracellular calcium. This is evidenced by the findings that chelation of extracellular calcium, expression of α 7 D44A or α 7 345-348A mutant subunits, or blockade of calcium store release compromised the ability of PNU120596 to increase intracellular calcium transients generated by α 7 ligand activation. Spatiotemporal stochastic modeling of calcium transient responses corroborates these results and indicates that α 7 receptor activation enables calcium microdomains locally and to lesser extent in the distant cytosol. From the model, allosteric modulation of the receptor activates CICR locally via ryanodine receptors and augments IICR through enhanced calcium influx due to prolonged α 7 nAChR opening. These findings provide a new mechanistic framework for understanding the effect of α 7 receptor allosteric modulation on both local and global calcium dynamics. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

Demographic, dietary, and urinary factors and 24-h urinary calcium excretion.

PubMed

Taylor, Eric N; Curhan, Gary C

2009-12-01

Higher urinary calcium is a risk factor for nephrolithiasis. This study delineated associations between demographic, dietary, and urinary factors and 24-h urinary calcium. Cross-sectional studies were conducted of 2201 stone formers (SF) and 1167 nonstone formers (NSF) in the Health Professionals Follow-up Study (men) and Nurses' Health Studies I and II (older and younger women). Median urinary calcium was 182 mg/d in men, 182 mg/d in older women, and 192 mg/d in younger women. Compared with NSF, urinary calcium as a fraction of calcium intake was 33 to 38% higher in SF (P values < or =0.01). In regression analyses, participants were combined because associations with urinary calcium were similar in each cohort and in SF and NSF. After multivariate adjustment, participants in the highest quartile of calcium intake excreted 18 mg/d more urinary calcium than those in the lowest (P trend =0.01). Caffeine and family history of nephrolithiasis were positively associated, whereas urinary potassium, thiazides, gout, and age were inversely associated, with urinary calcium. After multivariate adjustment, participants in the highest quartiles of urinary magnesium, sodium, sulfate, citrate, phosphorus, and volume excreted 71 mg/d, 37 mg/d, 44 mg/d, 61 mg/d, 37 mg/d, and 24 mg/d more urinary calcium, respectively, than participants in the lowest (P values trend < or =0.01). Intestinal calcium absorption and/or negative calcium balance is greater in SF than NSF. Higher calcium intakes at levels typically observed in free-living individuals are associated with only small increases in urinary calcium.

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

Multitrophic effects of calcium availability on invasive alien plants, birds, and bird prey items

Treesearch

Vince D' Amico; Greg Shriver; Jake Bowman; Meg Ballard; Whitney Wiest; Liz Tymkiw; Melissa Miller

2011-01-01

Acid rain alters forest soil calcium concentrations in two ways: (1) hydrogen ions displace exchangeable calcium adsorbed to soil surfaces, and (2) aluminum is released to soil water by acid rain and displaces adsorbed calcium. This increases the absorption of aluminum by plant roots, and decreases the absorption of calcium, causing calcium to be more readily leached...

Study on the Equilibrium Between Liquid Iron and Calcium Vapor

NASA Astrophysics Data System (ADS)

Berg, Martin; Lee, Jaewoo; Sichen, Du

2017-06-01

The solubility of calcium in liquid iron at 1823 K and 1873 K (1550 °C and 1600 °C) as a function of calcium potential was studied experimentally. The measurements were performed using a closed molybdenum holder in which liquid calcium and liquid iron were held at different temperatures. The results indicate a linear relationship between the activity of calcium, relative to pure liquid calcium, and the mole fraction of dissolved calcium in liquid iron, with a negligible temperature dependency in the ranges studied. The activity coefficient of calcium in liquid iron at infinite dilution, γ_{Ca(l0°, was calculated as 1551.

Effect of limestone reactivity and percent on production by dairy cows in early lactation.

PubMed

Nocek, J E; Braund, D G; English, J E

1983-12-01

Seventy-two Holstein cows (16 first lactation) were assigned to four treatments: A) normal-grind limestone (800 to 1000 mu) added to provide .77% calcium (total ration dry basis); B) fine-grind limestone (less than 150 mu) at .77% calcium; C) normal-grind at 1.15% calcium; and D) fine-grind limestone at 1.15% calcium. Cows fed diets containing .77% calcium had higher percent milk fat and fat yield than those fed 1.15% calcium diets, and cows fed fine-grind limestone had greater percent fat and fat yield than those fed normal-grind limestone. Four percent fat-corrected milk was higher for cows fed .77% calcium diets. Trends were similar for heifers in first lactation. Dry matter intake was higher for cows fed .77% calcium diets, and nutrient efficiency for milk synthesis favored cows fed fine-grind 1.15% calcium. Fecal pH was higher during wk 4 on treatment for cows fed high calcium diets; however, 8 wk were not different. Fecal starch and calcium and phosphorus in plasma were not different between treatments: however, heifers fed fine-grind 1.15% calcium showed a decrease of fecal starch with time.

Regulation of calcium signals in the nucleus by a nucleoplasmic reticulum

PubMed Central

Echevarría, Wihelma; Leite, M. Fatima; Guerra, Mateus T.; Zipfel, Warren R.; Nathanson, Michael H.

2013-01-01

Calcium is a second messenger in virtually all cells and tissues1. Calcium signals in the nucleus have effects on gene transcription and cell growth that are distinct from those of cytosolic calcium signals; however, it is unknown how nuclear calcium signals are regulated. Here we identify a reticular network of nuclear calcium stores that is continuous with the endoplasmic reticulum and the nuclear envelope. This network expresses inositol 1,4,5-trisphosphate (InsP3) receptors, and the nuclear component of InsP3-mediated calcium signals begins in its locality. Stimulation of these receptors with a little InsP3 results in small calcium signals that are initiated in this region of the nucleus. Localized release of calcium in the nucleus causes nuclear protein kinase C (PKC) to translocate to the region of the nuclear envelope, whereas release of calcium in the cytosol induces translocation of cytosolic PKC to the plasma membrane. Our findings show that the nucleus contains a nucleoplasmic reticulum with the capacity to regulate calcium signals in localized subnuclear regions. The presence of such machinery provides a potential mechanism by which calcium can simultaneously regulate many independent processes in the nucleus. PMID:12717445

Idiopathic hypercalciuria and formation of calcium renal stones

PubMed Central

Coe, Fredric L.; Worcester, Elaine M.; Evan, Andrew P.

2018-01-01

The most common presentation of nephrolithiasis is idiopathic calcium stones in patients without systemic disease. Most stones are primarily composed of calcium oxalate and form on a base of interstitial apatite deposits, known as Randall’s plaque. By contrast some stones are composed largely of calcium phosphate, as either hydroxyapatite or brushite (calcium monohydrogen phosphate), and are usually accompanied by deposits of calcium phosphate in the Bellini ducts. These deposits result in local tissue damage and might serve as a site of mineral overgrowth. Stone formation is driven by supersaturation of urine with calcium oxalate and brushite. The level of supersaturation is related to fluid intake as well as to the levels of urinary citrate and calcium. Risk of stone formation is increased when urine citrate excretion is <400 mg per day, and treatment with potassium citrate has been used to prevent stones. Urine calcium levels >200 mg per day also increase stone risk and often result in negative calcium balance. Reduced renal calcium reabsorption has a role in idiopathic hypercalciuria. Low sodium diets and thiazide-type diuretics lower urine calcium levels and potentially reduce the risk of stone recurrence and bone diseas PMID:27452364

The Yin and Yang of Calcium Effects on Synaptic Vesicle Endocytosis

PubMed Central

Wu, Xin-Sheng

2014-01-01

A large number of studies suggest that calcium triggers and accelerates vesicle endocytosis at many synapses and non-neuronal secretory cells. However, many studies show that prolonging the duration of the stimulation train, which induces more calcium influx, slows down endocytosis; and several studies suggest that instead of triggering endocytosis, calcium actually inhibits endocytosis. Here we addressed this apparent conflict at a large nerve terminal, the calyx of Held in rat brainstem, in which recent studies suggest that transient calcium increase up to tens of micromolar concentration at the micro/nano domain triggers endocytosis. By dialyzing 0–1 μm calcium into the calyx via a whole-cell pipette, we found that slow endocytosis was inhibited by calcium dialysis in a concentration-dependent manner. Thus, prolonged, small, and global calcium increase inhibits endocytosis, whereas transient and large calcium increase at the micro/nano domain triggers endocytosis and facilitates endocytosis. This yin and yang effect of calcium may reconcile apparent conflicts regarding whether calcium accelerates or inhibits endocytosis. Whether endocytosis is fast or slow depends on the net outcome between the yin and yang effect of calcium. PMID:24523554

Activity-dependent ATP-waves in the mouse neocortex are independent from astrocytic calcium waves.

PubMed

Haas, Brigitte; Schipke, Carola G; Peters, Oliver; Söhl, Goran; Willecke, Klaus; Kettenmann, Helmut

2006-02-01

In the corpus callosum, astrocytic calcium waves propagate via a mechanism involving ATP-release but not gap junctional coupling. In the present study, we report for the neocortex that calcium wave propagation depends on functional astrocytic gap junctions but is still accompanied by ATP-release. In acute slices obtained from the neocortex of mice deficient for astrocytic expression of connexin43, the calcium wave did not propagate. In contrast, in the corpus callosum and hippocampus of these mice, the wave propagated as in control animals. In addition to calcium wave propagation in astrocytes, ATP-release was recorded as a calcium signal from 'sniffer cells', a cell line expressing high-affinity purinergic receptors placed on the surface of the slice. The astrocyte calcium wave in the neocortex was accompanied by calcium signals in the 'sniffer cell' population. In the connexin43-deficient mice we recorded calcium signals from sniffer cells also in the absence of an astrocytic calcium wave. Our findings indicate that astrocytes propagate calcium signals by two separate mechanisms depending on the brain region and that ATP release can propagate within the neocortex independent from calcium waves.

Parallel temperature dependence of contracture-associated enzyme release due to anoxia, 2,4-dinitrophenol (DNP), or caffeine and the calcium paradox.

PubMed Central

Ganote, C. E.; Sims, M. A.

1984-01-01

Hypothermia during calcium-free perfusion of hearts protects them from injury caused by subsequent calcium repletion at 37 C (calcium paradox). Injury to calcium-free hearts is also associated with contracture caused by anoxia, 2,4-dinitrophenol (DNP), or caffeine. This study was done for the purpose of determining whether hypothermia during calcium-free perfusions protects hearts from contracture-associated injury. Langendorff-perfused rat hearts were studied in four experimental groups: I) Anoxia: Thirty minutes of anoxic perfusion at 37 C was followed by thirty minutes of anoxic calcium-free perfusion at 37-18 C. II) Calcium paradox: Five minutes of calcium-free perfusion at 37-18 C was followed by calcium repletion at 37 C. III, IVa) Caffeine or DNP: Five minutes of calcium-free perfusion at 37-18 C was followed by addition of 10 mM caffeine or 1 mM DNP in calcium-free medium at 37 C or, IVb) 1 mM DNP in calcium-free medium at 22 C. Injury was assessed by measurement of serial releases of creatine kinase (CK) in effluents and by cellular morphology. The results show that progressive hypothermia to 22 C during calcium-free perfusion periods produced a progressive reduction of CK release and morphologic evidence of injury due to anoxia, caffeine, or DNP, which closely paralleled protection of hearts from the calcium paradox. Protection from injury in all experimental groups was associated with preservation of sarcolemmal membrane integrity and prevention of cell separations at intercalated disk junctions. It is proposed that weakening of intercalated disks occurs during calcium-free perfusions and may be a cause of mechanical fragility of the sarcolemma. Hypothermia may protect hearts from contracture-associated injury by preserving the integrity of intercalated disk junctions during periods of extracellular calcium depletion. Images Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 PMID:6742111

Ionic calcium determination in skim milk with molecular probes and front-face fluorescence spectroscopy: simple linear regression.

PubMed

Gangidi, R R; Metzger, L E

2006-11-01

The purpose of this study was to determine if the ionic calcium content of skim milk could be determined using molecular probes and front-face fluorescence spectroscopy. Current methods for determining ionic calcium are not sensitive, overestimate ionic calcium, or require complex procedures. Molecular probes designed specifically for measuring ionic calcium could potentially be used to determine the ionic calcium content of skim milk. The goal of the current study was to develop foundation methods for future studies to determine ionic calcium directly in skim milk and other dairy products with molecular probes and fluorescence spectroscopy. In this study, the effect of pH on calcium-sensitive fluorescent probe (Rhod-5N and Fluo-5N) performance using various concentrations of skim milk was determined. The pH of diluted skim milk (1.9 to 8.9% skim milk), was adjusted to either 6.2 or 7.0, after which the samples were analyzed with fluorescent probes (1 microM) and front-face fluorescence spectroscopy. The ionic calcium content of each sample was also determined using a calcium ion-selective electrode. The results demonstrated that the ionic calcium content of each sample was highly correlated (R2 > 0.989) with the fluorescence intensities of the probe-calcium adduct using simple linear regression. Higher than suggested ionic calcium contents of 1,207 and 1,973 microM were determined with the probes (Fluo-5N and Rhod-5N) in diluted skim milk with pH 7.0 and 6.2, respectively. The fluorescence intensity of the probe-calcium adduct decreased with a decrease in pH for the same ionic calcium concentration. This study demonstrates that Fluo-5N and Rhod-5N can be used to determine the ionic-calcium content of diluted milk with front-face fluorescence spectroscopy. Furthermore, these probes may also have the potential to determine the ionic calcium content of undiluted skim milk.

Altered sarco(endo)plasmic reticulum calcium adenosine triphosphatase 2a content: Targets for heart failure therapy.

PubMed

Liu, Gang; Li, Si Qi; Hu, Ping Ping; Tong, Xiao Yong

2018-05-01

Sarco(endo)plasmic reticulum calcium adenosine triphosphatase is responsible for transporting cytosolic calcium into the sarcoplasmic reticulum and endoplasmic reticulum to maintain calcium homeostasis. Sarco(endo)plasmic reticulum calcium adenosine triphosphatase is the dominant isoform expressed in cardiac tissue, which is regulated by endogenous protein inhibitors, post-translational modifications, hormones as well as microRNAs. Dysfunction of sarco(endo)plasmic reticulum calcium adenosine triphosphatase is associated with heart failure, which makes sarco(endo)plasmic reticulum calcium adenosine triphosphatase a promising target for heart failure therapy. This review summarizes current approaches to ameliorate sarco(endo)plasmic reticulum calcium adenosine triphosphatase function and focuses on phospholamban, an endogenous inhibitor of sarco(endo)plasmic reticulum calcium adenosine triphosphatase, pharmacological tools and gene therapies.

Characterization of sea cucumber (stichopus japonicus) ovum hydrolysates: calcium chelation, solubility and absorption into intestinal epithelial cells.

PubMed

Sun, Na; Cui, Pengbo; Lin, Songyi; Yu, Cuiping; Tang, Yue; Wei, Ye; Xiong, Youling; Wu, Haitao

2017-10-01

Sea cucumber (Stichopus japonicus) ovum hydrolysates (SCOHs) chelated with calcium were produced to investigate the characteristics of calcium binding and solubility, as well as to study any effects on calcium absorption by human intestinal epithelial cells. The results of the present study show that the calcium-binding capacity of SCOHs depended greatly on the type of proteases. The maximum level of Ca binding (0.38 mmol L -1 ) occurred when trypsin was used, with a peptide yield of 85.7%. Investigation of the possible chelating modes between SCOHs and calcium ions indicated that calcium ions bound to SCOHs primarily via interactions with carboxyl oxygen and amino nitrogen atoms of Glu and Asp and also that the phosphoserine residues might be also responsible for SCOH-calcium chelation. Moreover, SCOH-calcium complexes maintained the solubility of calcium under simulated gastrointestinal digestion, regardless of the presence of dietary components such as oxalate. Furthermore, SCOH-Ca led to higher peak intracellular [Ca 2+ ] i in both Caco-2 cells (338.3 nmol L -1 versus 269.6 nmol L -1 ) and HT-29 cells (373.9 nmol L -1 versus 271.7 nmol L -1 ) than casein phosphopeptide-Ca. Carboxyl oxygen and amino nitrogen atoms in the SCOHs could bind calcium ions, forming SCOH-calcium complexes. These complexes improved calcium solubility under simulated gastrointestinal digestion and also promoted calcium absorption in Caco-2 and HT-29 cells. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Studying dyadic structure-function relationships: a review of current modeling approaches and new insights into Ca2+ (mis)handling.

PubMed

Maleckar, Mary M; Edwards, Andrew G; Louch, William E; Lines, Glenn T

2017-01-01

Excitation-contraction coupling in cardiac myocytes requires calcium influx through L-type calcium channels in the sarcolemma, which gates calcium release through sarcoplasmic reticulum ryanodine receptors in a process known as calcium-induced calcium release, producing a myoplasmic calcium transient and enabling cardiomyocyte contraction. The spatio-temporal dynamics of calcium release, buffering, and reuptake into the sarcoplasmic reticulum play a central role in excitation-contraction coupling in both normal and diseased cardiac myocytes. However, further quantitative understanding of these cells' calcium machinery and the study of mechanisms that underlie both normal cardiac function and calcium-dependent etiologies in heart disease requires accurate knowledge of cardiac ultrastructure, protein distribution and subcellular function. As current imaging techniques are limited in spatial resolution, limiting insight into changes in calcium handling, computational models of excitation-contraction coupling have been increasingly employed to probe these structure-function relationships. This review will focus on the development of structural models of cardiac calcium dynamics at the subcellular level, orienting the reader broadly towards the development of models of subcellular calcium handling in cardiomyocytes. Specific focus will be given to progress in recent years in terms of multi-scale modeling employing resolved spatial models of subcellular calcium machinery. A review of the state-of-the-art will be followed by a review of emergent insights into calcium-dependent etiologies in heart disease and, finally, we will offer a perspective on future directions for related computational modeling and simulation efforts.

Effects of soaking and acidification on physicochemical properties of calcium-fortified rice.

PubMed

Sirisoontaralak, Porntip; Limboon, Pailin; Jatuwong, Sujitra; Chavanalikit, Arusa

2016-06-01

Calcium-fortified rice was prepared by soaking milled rice in calcium lactate solution, steaming and drying, and physicochemical properties were determined to evaluate effects of calcium concentration (0, 30, 50 g L(-1) ), soaking temperature (ambient temperature, 40 °C, 60 °C) and acidification. Calcium-fortified rice had less lightness. More total solid loss was observed, especially at high soaking temperature. Harder texture was detected with increased calcium concentration. Calcium fortification lowered pasting viscosity of milled rice. Panelists accepted all fortified rice; however, only rice soaked at 50 g L(-1) concentration could be claimed as a good source of calcium. Increasing of soaking temperature induced more penetration of calcium to rice kernels but calcium was lost more easily after washing. With addition of acetic acid to the soaking solution, enriched calcium content was comparable to that of high soaking temperature but with better retention after washing and calcium solubility was improved. Acid induced reduction of lightness and cooked rice hardness but increased total solid loss and pasting viscosity. Although the taste of acetic acid remained, panelists still accepted the fortified rice. Calcium-fortified rice (190.47-194.3 mg 100 g(-1) ) could be successfully produced by soaking milled rice in 50 g L(-1) calcium lactate solution at 40 °C or at ambient temperature with acidification. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Isolation and identification of calcium-chelating peptides from Pacific cod skin gelatin and their binding properties with calcium.

PubMed

Wu, Wenfei; Li, Bafang; Hou, Hu; Zhang, Hongwei; Zhao, Xue

2017-12-13

A calcium-chelating peptide is considered to have the ability to improve calcium absorption. In this study, Pacific cod skin gelatin hydrolysates treated with trypsin for 120 min exhibited higher calcium-chelating activity. Sequential chromatography, involving hydroxyapatite affinity chromatography and reversed phase high performance liquid chromatography, was used for the purification of calcium-chelating peptides. Two novel peptides with the typical characteristics of collagen were sequenced as GDKGESGEAGER and GEKGEGGHR based on LC-HRMS/MS, which showed a high affinity to calcium. Calcium-peptide complexation was further characterized by ESI-MS (MS and MS/MS) and FTIR spectroscopy. The results showed that the complexation of the two peptides with calcium was conducted mainly at the ratio of 1 : 1. The amino terminal group and the peptide bond of the peptide backbone as well as the amino group of the lysine side chain and the carboxylate of the glutamate side chain were the possible calcium binding sites for the two peptides. Meanwhile, several amino acid side chain groups, including the hydroxyl (Ser) and carboxylate (Asp) of GDKGESGEAGER and the imine (His) of GEKGEGGHR, were crucial in the complexation. The arginine residue in GEKGEGGHR also participated in the calcium coordination. Additionally, several active fragments with calcium-chelating activity were obtained using MS/MS spectra, including GDKGESGEAGE, GEAGER, GEK, EKG and KGE. This study suggests that gelatin-derived peptides have the potential to be used as a calcium-chelating ingredient to combat calcium deficiency.

Voltage-gated calcium flux mediates Escherichia coli mechanosensation.

PubMed

Bruni, Giancarlo N; Weekley, R Andrew; Dodd, Benjamin J T; Kralj, Joel M

2017-08-29

Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli , including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings.

Voltage-gated calcium flux mediates Escherichia coli mechanosensation

PubMed Central

Weekley, R. Andrew; Dodd, Benjamin J. T.

2017-01-01

Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli, including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings. PMID:28808010

Aluminum hydroxide, calcium carbonate and calcium acetate in chronic intermittent hemodialysis patients.

PubMed

Janssen, M J; van der Kuy, A; ter Wee, P M; van Boven, W P

1996-02-01

Prevention of secondary hyperparathyroidism in uremia necessitates correction of hyperphosphatemia and hypocalcemia. In order to avoid aluminum toxicity, calcium containing phosphate binders are used increasingly, instead of aluminium hydroxide. Recent studies have shown that calcium acetate has many characteristics of an ideal phosphate binder. It is, for instance, a more readily soluble salt compared with calcium carbonate. This advantage might, however, disappear if calcium carbonate is taken on an empty stomach, a few minutes before meals. We examined the efficacy of three different phosphate binding agents in a randomized prospective study of 53 patients on regular hemodialysis. Bicarbonate dialyses were performed with a dialysate calcium concentration of 1.75 mmol/l. After a three-week wash-out period, patients received either aluminum hydroxide (control group), calcium acetate, or calcium carbonate as their phosphate binder. Patients were instructed to take the calcium salts a few minutes before meals on an empty stomach, and aluminum hydroxide during meals. Serum calcium, phosphate, intact parathormone, and alkaline phosphatase levels were determined every month. Patient compliance was estimated every month by asking the patients which phosphate binder and what daily dose they had used. Aluminum hydroxide tended to be the most effective phosphate binder. The mean +/- SEM required daily dose of calcium acetate at 12 months was 5.04 +/- 0.60 g, corresponding to 10.1 +/- 1.20 tablets of 500 mg. Co-medication with aluminum hydroxide, however, was needed (1.29 +/- 0.54 g per day, corresponding to 2.6 +/- 1.08 tablets of 500 mg). The required daily calcium carbonate dose appeared to be 2.71 +/- 0.48 g, corresponding to 5.4 +/- 0.95 capsules of 500 mg, with an adjuvant daily aluminum hydroxide dose of 0.69 +/- 0.27 g, corresponding to 1.4 +/- 0.55 tablets of 500 mg (p = 0.0055). Thus, the mean daily doses of elemental calcium were comparable between the calcium acetate and calcium carbonate-treated patients (1.28 +/- 0.15 g versus 1.09 +/- 0.19 g; n.s.). The incidence of hypercalcemic episodes (albumin-corrected serum calcium levels above 2.80 mmol/l) in the calcium acetate-treated group was 18% versus 31% in the calcium carbonate-treated group (p < 0.005). None of the aluminum hydroxide-treated patients experienced hypercalcemic episodes. Mean serum concentrations of alkaline phosphatase, intact parathormone, and aluminum did not differ between the groups. In chronic intermittent hemodialysis patients, per gram administered elemental calcium phosphate binding with either calcium acetate or calcium carbonate is equivalent, provided that calcium carbonate is taken on an empty stomach a few minutes before meals. The number of capsules calcium carbonate, but also the total amount in grams, necessary to keep serum phosphate and intact parathormone levels into an acceptable range then is significantly less. This might improve patient compliance.

Ultracytochemical visualization of calcium distribution in heart cells and erythrocytes of zebrafish Danio rerio.

PubMed

Niksirat, Hamid; Steinbach, Christoph

2018-05-24

Detection of patterns of subcellular calcium distribution in the cardiovascular system can contribute to understanding its role in cardiac and blood function. The present study localized calcium in heart atrium, ventricle, and bulbus arteriosus as well as in erythrocytes of zebrafish Danio rerio using an oxalate-pyroantimonate technique combined with transmission electron microscopy. Intracellular calcium stores were detected in caveolae, mitochondria, and the nuclei of several zebrafish cardiac cell types. Melanin pigmentation containing calcium stores was detected in the pericardial cavity. Melanin might be an extracellular source of calcium for heart beating and/or a lubricant to prevent friction during beating process. Calcium deposits were also detected in the plasma membrane, cytoplasm and nucleus of erythrocytes as well as in blood plasma. Possible exchange of calcium between erythrocytes and blood plasma was observed. Interactions of such calcium stores and possible contribution of extracellular calcium stores such as melanin pigmentation to supply calcium for vital functions of heart cells should be addressed in future studies. Copyright © 2018 Elsevier Ltd. All rights reserved.

Calcium Signaling in Taste Cells

PubMed Central

Medler, Kathryn F.

2014-01-01

The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. PMID:25450977

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium citrate. 184.1195 Section 184.1195 Food... GRAS § 184.1195 Calcium citrate. (a) Calcium citrate (Ca3(C6H5O7)2·4H2O, CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with calcium hydroxide or...

Calcium fertilization increases the concentration of calcium in sapwood and calcium oxalate in foliage of red spruce

Treesearch

Kevin T. Smith; Walter C. Shortle; Jon H. Connolly; Rakesh Minocha; Jody Jellison

2009-01-01

Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of...

Live Imaging of Calcium Dynamics during Axon Degeneration Reveals Two Functionally Distinct Phases of Calcium Influx

PubMed Central

Yamagishi, Yuya; Tessier-Lavigne, Marc

2015-01-01

Calcium is a key regulator of axon degeneration caused by trauma and disease, but its specific spatial and temporal dynamics in injured axons remain unclear. To clarify the function of calcium in axon degeneration, we observed calcium dynamics in single injured neurons in live zebrafish larvae and tested the temporal requirement for calcium in zebrafish neurons and cultured mouse DRG neurons. Using laser axotomy to induce Wallerian degeneration (WD) in zebrafish peripheral sensory axons, we monitored calcium dynamics from injury to fragmentation, revealing two stereotyped phases of axonal calcium influx. First, axotomy triggered a transient local calcium wave originating at the injury site. This initial calcium wave only disrupted mitochondria near the injury site and was not altered by expression of the protective WD slow (WldS) protein. Inducing multiple waves with additional axotomies did not change the kinetics of degeneration. In contrast, a second phase of calcium influx occurring minutes before fragmentation spread as a wave throughout the axon, entered mitochondria, and was abolished by WldS expression. In live zebrafish, chelating calcium after the first wave, but before the second wave, delayed the progress of fragmentation. In cultured DRG neurons, chelating calcium early in the process of WD did not alter degeneration, but chelating calcium late in WD delayed fragmentation. We propose that a terminal calcium wave is a key instructive component of the axon degeneration program. SIGNIFICANCE STATEMENT Axon degeneration resulting from trauma or neurodegenerative disease can cause devastating deficits in neural function. Understanding the molecular and cellular events that execute axon degeneration is essential for developing treatments to address these conditions. Calcium is known to contribute to axon degeneration, but its temporal requirements in this process have been unclear. Live calcium imaging in severed zebrafish neurons and temporally controlled pharmacological treatments in both zebrafish and cultured mouse sensory neurons revealed that axonal calcium influx late in the degeneration process regulates axon fragmentation. These findings suggest that temporal considerations will be crucial for developing treatments for diseases associated with axon degeneration. PMID:26558774

The probability of quantal secretion near a single calcium channel of an active zone.

PubMed Central

Bennett, M R; Farnell, L; Gibson, W G

2000-01-01

A Monte Carlo analysis has been made of calcium dynamics and quantal secretion at microdomains in which the calcium reaches very high concentrations over distances of <50 nm from a channel and for which calcium dynamics are dominated by diffusion. The kinetics of calcium ions in microdomains due to either the spontaneous or evoked opening of a calcium channel, both of which are stochastic events, are described in the presence of endogenous fixed and mobile buffers. Fluctuations in the number of calcium ions within 50 nm of a channel are considerable, with the standard deviation about half the mean. Within 10 nm of a channel these numbers of ions can give rise to calcium concentrations of the order of 100 microM. The temporal changes in free calcium and calcium bound to different affinity indicators in the volume of an entire varicosity or bouton following the opening of a single channel are also determined. A Monte Carlo analysis is also presented of how the dynamics of calcium ions at active zones, after the arrival of an action potential and the stochastic opening of a calcium channel, determine the probability of exocytosis from docked vesicles near the channel. The synaptic vesicles in active zones are found docked in a complex with their calcium-sensor associated proteins and a voltage-sensitive calcium channel, forming a secretory unit. The probability of quantal secretion from an isolated secretory unit has been determined for different distances of an open calcium channel from the calcium sensor within an individual unit: a threefold decrease in the probability of secretion of a quantum occurs with a doubling of the distance from 25 to 50 nm. The Monte Carlo analysis also shows that the probability of secretion of a quantum is most sensitive to the size of the single-channel current compared with its sensitivity to either the binding rates of the sites on the calcium-sensor protein or to the number of these sites that must bind a calcium ion to trigger exocytosis of a vesicle. PMID:10777721

Radiological study of the effect of low calcium diet on the mineral metabolism of bone tissue. With reference to mineralization in callus (in Japanese)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, K.

1972-01-01

Deficiency of available food material due either to poor diet or to malabsorption may adversely affect the skeleton. To study the affection, DDN mice were fed low calcium diet to induce low calcium state corresponding to malabsorption of calcium from the intestine. The femur was fractured manually. Then, calcium deposition in the callus was observed by microradiography and tracer technics with /sup 47/Ca. Increase of the body weight in mice fed low calcium diet was much slower than in the control. The affection of the low calcium diet on bone tissue appeared as a decrease of precipitation of calcium salt.more » This tendency was also observed in callus, Tracer study with /sup 47/Ca was performed in mice fed the low calcium diet for 24 days. Incorporation activity of calcium was generally high in each organ except the kidney. Callus in the site of the fracture in mice fed a low calcium diet was formed to the same degree as the control, although the amount of precipitated calcium in it was significantly poorer. In summary, insufficient mineralization in relation to osteogenesis occurred when the supply of the requisite electrolytes was insufficient or inappropriate. On the other hand, the uptake rate of calcinm in the callus was elevated even in the calcium deficient state. (auth)« less

Depletion of intracellular calcium stores facilitates the influx of extracellular calcium in platelet derived growth factor stimulated A172 glioblastoma cells.

PubMed

Vereb, G; Szöllösi, J; Mátyus, L; Balázs, M; Hyun, W C; Feuerstein, B G

1996-05-01

Calcium signaling in non-excitable cells is the consequence of calcium release from intracellular stores, at times followed by entry of extracellular calcium through the plasma membrane. To study whether entry of calcium depends upon the level of saturation of intracellular stores, we measured calcium channel opening in the plasma membrane of single confluent A172 glioblastoma cells stimulated with platelet derived growth factor (PDGF) and/or bradykinin (BK). We monitored the entry of extracellular calcium by measuring manganese quenching of Indo-1 fluorescence. PDGF raised intracellular calcium concentration ([Ca2+]i) after a dose-dependent delay (tdel) and then opened calcium channels after a dose-independent delay (tch). At higher doses (> 3 nM), BK increased [Ca2+]i after a tdel approximately 0 s, and tch decreased inversely with both dose and peak [Ca2+]i. Experiments with thapsigargin (TG), BK, and PDGF indicated that BK and PDGF share intracellular Ca2+ pools that are sensitive to TG. When these stores were depleted by treatment with BK and intracellular BAPTA, tdel did not change, but tch fell to almost 0 s in PDGF stimulated cells, indicating that depletion of calcium stores affects calcium channel opening in the plasma membrane. Our data support the capacitative model for calcium channel opening and the steady-state model describing quantal Ca2+ release from intracellular stores.

Molten salt applications in materials processing

NASA Astrophysics Data System (ADS)

Mishra, Brajendra; Olson, David L.

2005-02-01

The science of molten salt electrochemistry for electrowinning of reactive metals, such as calcium, and its in situ application in pyro-reduction has been described. Calcium electrowinning has been performed in a 5 10 wt% calcium oxide calcium chloride molten salt by the electrolytic dissociation of calcium oxide. This electrolysis requires the use of a porous ceramic sheath around the anode to keep the cathodically deposited calcium and the anodic gases separate. Stainless steel cathode and graphite anode have been used in the temperature range of 850 950 °C. This salt mixture is produced as a result of the direct oxide reduction (DOR) of reactive metal oxides by calcium in a calcium chloride bath. The primary purpose of this process is to recover the expensive calcium reductant and to recycle calcium chloride. Experimental data have been included to justify the suitability as well as limitations of the electrowinning process. Transport of oxygen ions through the sheath is found to be the rate controlling step. Under the constraints of the reactor design, a calcium recovery rate of approx. 150 g/h was achieved. Feasibility of a process to produce metals by pyrometallurgical reduction, using the calcium reductant produced electrolytically within the same reactor, has been shown in a hybrid process. Several processes are currently under investigation to use this electrowon calcium for in situ reduction of metal oxides.

Calcium Biofortification: Three Pronged Molecular Approaches for Dissecting Complex Trait of Calcium Nutrition in Finger Millet (Eleusine coracana) for Devising Strategies of Enrichment of Food Crops

PubMed Central

Sharma, Divya; Jamra, Gautam; Singh, Uma M.; Sood, Salej; Kumar, Anil

2017-01-01

Calcium is an essential macronutrient for plants and animals and plays an indispensable role in structure and signaling. Low dietary intake of calcium in humans has been epidemiologically linked to various diseases which can have serious health consequences over time. Major staple food-grains are poor source of calcium, however, finger millet [Eleusine coracana (L.) Gaertn.], an orphan crop has an immense potential as a nutritional security crop due to its exceptionally high calcium content. Understanding the existing genetic variation as well as molecular mechanisms underlying the uptake, transport, accumulation of calcium ions (Ca2+) in grains is of utmost importance for development of calcium bio-fortified crops. In this review, we have discussed molecular mechanisms involved in calcium accumulation and transport thoroughly, emphasized the role of molecular breeding, functional genomics and transgenic approaches to understand the intricate mechanism of calcium nutrition in finger millet. The objective is to provide a comprehensive up to date account of molecular mechanisms regulating calcium nutrition and highlight the significance of bio-fortification through identification of potential candidate genes and regulatory elements from finger millet to alleviate calcium malnutrition. Hence, finger millet could be used as a model system for explaining the mechanism of elevated calcium (Ca2+) accumulation in its grains and could pave way for development of nutraceuticals or designer crops. PMID:28144246

Calcium Biofortification: Three Pronged Molecular Approaches for Dissecting Complex Trait of Calcium Nutrition in Finger Millet (Eleusine coracana) for Devising Strategies of Enrichment of Food Crops.

PubMed

Sharma, Divya; Jamra, Gautam; Singh, Uma M; Sood, Salej; Kumar, Anil

2016-01-01

Calcium is an essential macronutrient for plants and animals and plays an indispensable role in structure and signaling. Low dietary intake of calcium in humans has been epidemiologically linked to various diseases which can have serious health consequences over time. Major staple food-grains are poor source of calcium, however, finger millet [ Eleusine coracana (L.) Gaertn.], an orphan crop has an immense potential as a nutritional security crop due to its exceptionally high calcium content. Understanding the existing genetic variation as well as molecular mechanisms underlying the uptake, transport, accumulation of calcium ions (Ca 2+ ) in grains is of utmost importance for development of calcium bio-fortified crops. In this review, we have discussed molecular mechanisms involved in calcium accumulation and transport thoroughly, emphasized the role of molecular breeding, functional genomics and transgenic approaches to understand the intricate mechanism of calcium nutrition in finger millet. The objective is to provide a comprehensive up to date account of molecular mechanisms regulating calcium nutrition and highlight the significance of bio-fortification through identification of potential candidate genes and regulatory elements from finger millet to alleviate calcium malnutrition. Hence, finger millet could be used as a model system for explaining the mechanism of elevated calcium (Ca 2+ ) accumulation in its grains and could pave way for development of nutraceuticals or designer crops.

21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate...

21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

Space Flight Calcium: Implications for Astronaut Health, Spacecraft Operations, and Earth

PubMed Central

Smith, Scott M.; McCoy, Torin; Gazda, Daniel; Morgan, Jennifer L. L.; Heer, Martina; Zwart, Sara R.

2012-01-01

The space flight environment is known to induce bone loss and, subsequently, calcium loss. The longer the mission, generally the more bone and calcium are lost. This review provides a history of bone and calcium studies related to space flight and highlights issues related to calcium excretion that the space program must consider so that urine can be recycled. It also discusses a novel technique using natural stable isotopes of calcium that will be helpful in the future to determine calcium and bone balance during space flight. PMID:23250146

Circadian oscillations of cytosolic and chloroplastic free calcium in plants

NASA Technical Reports Server (NTRS)

Johnson, C. H.; Knight, M. R.; Kondo, T.; Masson, P.; Sedbrook, J.; Haley, A.; Trewavas, A.

1995-01-01

Tobacco and Arabidopsis plants, expressing a transgene for the calcium-sensitive luminescent protein apoaequorin, revealed circadian oscillations in free cytosolic calcium that can be phase-shifted by light-dark signals. When apoaequorin was targeted to the chloroplast, circadian chloroplast calcium rhythms were likewise observed after transfer of the seedlings to constant darkness. Circadian oscillations in free calcium concentrations can be expected to control many calcium-dependent enzymes and processes accounting for circadian outputs. Regulation of calcium flux is therefore fundamental to the organization of circadian systems.

Space flight calcium: implications for astronaut health, spacecraft operations, and Earth.

PubMed

Smith, Scott M; McCoy, Torin; Gazda, Daniel; Morgan, Jennifer L L; Heer, Martina; Zwart, Sara R

2012-12-18

The space flight environment is known to induce bone loss and, subsequently, calcium loss. The longer the mission, generally the more bone and calcium are lost. This review provides a history of bone and calcium studies related to space flight and highlights issues related to calcium excretion that the space program must consider so that urine can be recycled. It also discusses a novel technique using natural stable isotopes of calcium that will be helpful in the future to determine calcium and bone balance during space flight.

Acoustic and Hydrodynamic Cavitations for Nano CaCO3 Synthesis

NASA Astrophysics Data System (ADS)

Sonawane, Shirish H.; Kulkarni, Ravindra D.

Calcium carbonate is a common inorganic compound known as limestone. Calcium carbonate has many applications in industries such as medicine, agriculture, paint plastic and surface coatings etc. The vast majority of calcium carbonate used in industry is extracted by mining process. Pure calcium carbonate (e.g. for food or pharmaceutical use), is synthesized by passing carbon dioxide into a solution of calcium hydroxide slurry. In this process calcium carbonate precipitates out, and this grade of product is referred to as precipitate calcium carbonate (abbreviated as PCC).

Egg Shell and Oyster Shell Powder as Alternatives for Synthetic Phosphate: Effects on the Quality of Cooked Ground Pork Products

PubMed Central

2017-01-01

This study aimed to determine the optimal ratio of natural calcium powders (oyster shell and egg shell calcium) as synthetic phosphate replacers in pork products. Ground pork samples were subjected to six treatments, as follows: control (−) (no phosphate added), control (+) (0.3% phosphate blend added), treatment 1 (0.5% oyster shell calcium powder added), treatment 2 (0.3% oyster shell calcium powder and 0.2% egg shell calcium powder added), treatment 3 (0.2% oyster shell calcium powder and 0.3% egg shell calcium powder added), and treatment 4 (0.5% egg shell calcium powder added). The addition of natural calcium powders resulted in an increase in the pH values of meat products, regardless of whether they were used individually or mixed. The highest cooking loss was observed (p<0.05) in the negative control samples, whereas the cooking loss in samples with natural calcium powder added was similar (p>0.05) to that in the positive control samples. CIE L* values decreased as the amount of added egg shell calcium powder increased. CIE a* values were higher (p<0.05) in samples containing natural calcium powder (treatments 1, 2, 3, and 4) than in the positive control. The combination of oyster shell calcium powder and egg shell powder (treatment 2 or 3) was effective for the improvement of textural properties of the pork products. The findings show that the combined use of 0.2% oyster shell calcium and 0.3% egg shell calcium should enable the replacement of synthetic phosphate in the production of cooked pork products with desirable qualities. PMID:28943770

Trends in calcium supplementation, National Health and Nutrition Examination Survey (NHANES) 1999-2014.

PubMed

Rooney, Mary R; Michos, Erin D; Hootman, Katie C; Harnack, Lisa; Lutsey, Pamela L

2018-06-01

Long-term outcomes of supplemental calcium are inadequately understood. Recent research suggests that calcium from supplements may not be entirely free from unintended health consequences. Consequently, it is important to understand patterns and trends in use of calcium supplements. To report trends in supplemental calcium intake between 1999 and 2014, using NHANES data, overall and stratified by sex, race/ethnicity and age. A total of 42,038 adult NHANES participants were included in this analysis. For each survey period, we calculated the prevalence of calcium supplement use exceeding the Estimated Average Requirement (EAR) and Tolerable Upper Intake Levels (UL), and mean daily supplemental calcium dose among calcium-containing supplement users. Sample weights were applied. Linear regression was used to examine trends. Overall, the prevalence of calcium supplement use at a dose ≥EAR increased between 1999 and 2000 and 2013-2014, from 2.5% (95% CI: 1.9-3.3%) to 4.6% (3.8-5.5%). Use ≥EAR peaked in 2003-2004 at 6.7% (5.3-8.5%) (p-quadratic trend<0.001). Mean supplemental calcium intake peaked in 2007-2008, thereafter decreasing (p-quadratic trend<0.001). The overall prevalence of intake ≥UL from supplemental calcium in 2013-2014 was 0.4% (0.2-0.8%). Use of supplemental calcium ≥UL peaked during 2007-2008 at 1.2% (0.7-2.0%). In all time periods, supplemental calcium intake tended to be greater among women, non-Hispanic whites and adults >60years. We described the prevalence of U.S. adults consuming supplemental calcium ≥UL and ≥ EAR. While few were consuming supplemental calcium ≥UL, consumption ≥EAR was not uncommon, especially among women, non-Hispanic whites and older adults. Copyright © 2018 Elsevier Inc. All rights reserved.

Calcium signaling properties of a thyrotroph cell line, mouse TαT1 cells.

PubMed

Tomić, Melanija; Bargi-Souza, Paula; Leiva-Salcedo, Elias; Nunes, Maria Tereza; Stojilkovic, Stanko S

2015-12-01

TαT1 cells are mouse thyrotroph cell line frequently used for studies on thyroid-stimulating hormone beta subunit gene expression and other cellular functions. Here we have characterized calcium-signaling pathways in TαT1 cells, an issue not previously addressed in these cells and incompletely described in native thyrotrophs. TαT1 cells are excitable and fire action potentials spontaneously and in response to application of thyrotropin-releasing hormone (TRH), the native hypothalamic agonist for thyrotrophs. Spontaneous electrical activity is coupled to small amplitude fluctuations in intracellular calcium, whereas TRH stimulates both calcium mobilization from intracellular pools and calcium influx. Non-receptor-mediated depletion of intracellular pool also leads to a prominent facilitation of calcium influx. Both receptor and non-receptor stimulated calcium influx is substantially attenuated but not completely abolished by inhibition of voltage-gated calcium channels, suggesting that depletion of intracellular calcium pool in these cells provides a signal for both voltage-independent and -dependent calcium influx, the latter by facilitating the pacemaking activity. These cells also express purinergic P2Y1 receptors and their activation by extracellular ATP mimics TRH action on calcium mobilization and influx. The thyroid hormone triiodothyronine prolongs duration of TRH-induced calcium spikes during 30-min exposure. These data indicate that TαT1 cells are capable of responding to natively feed-forward TRH signaling and intrapituitary ATP signaling with acute calcium mobilization and sustained calcium influx. Amplification of TRH-induced calcium signaling by triiodothyronine further suggests the existence of a pathway for positive feedback effects of thyroid hormones probably in a non-genomic manner. Published by Elsevier Ltd.

Protein kinases as mediators of fluid shear stress stimulated signal transduction in endothelial cells: a hypothesis for calcium-dependent and calcium-independent events activated by flow.

PubMed

Berk, B C; Corson, M A; Peterson, T E; Tseng, H

1995-12-01

Fluid shear stress regulates endothelial cell function, but the signal transduction mechanisms involved in mechanotransduction remain unclear. Recent findings demonstrate that several intracellular kinases are activated by mechanical forces. In particular, members of the mitogen-activated protein (MAP) kinase family are stimulated by hyperosmolarity, stretch, and stress such as heat shock. We propose a model for mechanotransduction in endothelial cells involving calcium-dependent and calcium-independent protein kinase pathways. The calcium-dependent pathway involves activation of phospholipase C, hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), increases in intracellular calcium and stimulation of kinases such as calcium-calmodulin and C kinases (PKC). The calcium-independent pathway involves activation of a small GTP-binding protein and stimulation of calcium-independent PKC and MAP kinases. The calcium-dependent pathway mediates the rapid, transient response to fluid shear stress including activation of nitric oxide synthase (NOS) and ion transport. In contrast, the calcium-independent pathway mediates a slower response including the sustained activation of NOS and changes in cell morphology and gene expression. We propose that focal adhesion complexes link the calcium-dependent and calcium-independent pathways by regulating activity of phosphatidylinositol 4-phosphate (PIP) 5-kinase (which regulates PIP2 levels) and p125 focal adhesion kinase (FAK, which phosphorylates paxillin and interacts with cytoskeletal proteins). This model predicts that dynamic interactions between integrin molecules present in focal adhesion complexes and membrane events involved in mechanotransduction will be integrated by calcium-dependent and calcium-independent kinases to generate intracellular signals involved in the endothelial cell response to flow.

Intestinal absorption and renal reabsorption of calcium throughout postnatal development

PubMed Central

Beggs, Megan R

2017-01-01

Calcium is vital for many physiological functions including bone mineralization. Postnatal deposition of calcium into bone is greatest in infancy and continues through childhood and adolescence until peek mineral density is reached in early adulthood. Thereafter, bone mineral density remains static until it eventually declines in later life. A positive calcium balance, i.e. more calcium absorbed than excreted, is crucial to bone deposition during growth and thus to peek bone mineral density. Dietary calcium is absorbed from the intestine into the blood. It is then filtered by the renal glomerulus and either reabsorbed by the tubule or excreted in the urine. Calcium can be (re)absorbed across intestinal and renal epithelia via both transcellular and paracellular pathways. Current evidence suggests that significant intestinal and renal calcium transport changes occur throughout development. However, the molecular details of these alterations are incompletely delineated. Here we first briefly review the current model of calcium transport in the intestine and renal tubule in the adult. Then, we describe what is known with regard to calcium handling through postnatal development, and how alterations may aid in mediating a positive calcium balance. The role of transcellular and paracellular calcium transport pathways and the contribution of specific intestinal and tubular segments vary with age. However, the current literature highlights knowledge gaps in how specifically intestinal and renal calcium (re)absorption occurs early in postnatal development. Future research should clarify the specific changes in calcium transport throughout early postnatal development including mediators of these alterations enabling appropriate bone mineralization. Impact statement This mini review outlines the current state of knowledge pertaining to the molecules and mechanisms maintaining a positive calcium balance throughout postnatal development. This process is essential to achieving optimal bone mineral density in early adulthood, thereby lowering the lifetime risk of osteoporosis. PMID:28346014

Egg Shell and Oyster Shell Powder as Alternatives for Synthetic Phosphate: Effects on the Quality of Cooked Ground Pork Products.

PubMed

Cho, Min Guk; Bae, Su Min; Jeong, Jong Youn

2017-01-01

This study aimed to determine the optimal ratio of natural calcium powders (oyster shell and egg shell calcium) as synthetic phosphate replacers in pork products. Ground pork samples were subjected to six treatments, as follows: control (-) (no phosphate added), control (+) (0.3% phosphate blend added), treatment 1 (0.5% oyster shell calcium powder added), treatment 2 (0.3% oyster shell calcium powder and 0.2% egg shell calcium powder added), treatment 3 (0.2% oyster shell calcium powder and 0.3% egg shell calcium powder added), and treatment 4 (0.5% egg shell calcium powder added). The addition of natural calcium powders resulted in an increase in the pH values of meat products, regardless of whether they were used individually or mixed. The highest cooking loss was observed ( p <0.05) in the negative control samples, whereas the cooking loss in samples with natural calcium powder added was similar ( p >0.05) to that in the positive control samples. CIE L* values decreased as the amount of added egg shell calcium powder increased. CIE a* values were higher ( p <0.05) in samples containing natural calcium powder (treatments 1, 2, 3, and 4) than in the positive control. The combination of oyster shell calcium powder and egg shell powder (treatment 2 or 3) was effective for the improvement of textural properties of the pork products. The findings show that the combined use of 0.2% oyster shell calcium and 0.3% egg shell calcium should enable the replacement of synthetic phosphate in the production of cooked pork products with desirable qualities.

Demographic, Dietary, and Urinary Factors and 24-h Urinary Calcium Excretion

PubMed Central

Curhan, Gary C.

2009-01-01

Background and objectives: Higher urinary calcium is a risk factor for nephrolithiasis. This study delineated associations between demographic, dietary, and urinary factors and 24-h urinary calcium. Design, setting, participants, & measurements: Cross-sectional studies were conducted of 2201 stone formers (SF) and 1167 nonstone formers (NSF) in the Health Professionals Follow-up Study (men) and Nurses' Health Studies I and II (older and younger women). Results: Median urinary calcium was 182 mg/d in men, 182 mg/d in older women, and 192 mg/d in younger women. Compared with NSF, urinary calcium as a fraction of calcium intake was 33 to 38% higher in SF (P values ≤0.01). In regression analyses, participants were combined because associations with urinary calcium were similar in each cohort and in SF and NSF. After multivariate adjustment, participants in the highest quartile of calcium intake excreted 18 mg/d more urinary calcium than those in the lowest (P trend =0.01). Caffeine and family history of nephrolithiasis were positively associated, whereas urinary potassium, thiazides, gout, and age were inversely associated, with urinary calcium. After multivariate adjustment, participants in the highest quartiles of urinary magnesium, sodium, sulfate, citrate, phosphorus, and volume excreted 71 mg/d, 37 mg/d, 44 mg/d, 61 mg/d, 37 mg/d, and 24 mg/d more urinary calcium, respectively, than participants in the lowest (P values trend ≤0.01). Conclusions: Intestinal calcium absorption and/or negative calcium balance is greater in SF than NSF. Higher calcium intakes at levels typically observed in free-living individuals are associated with only small increases in urinary calcium. PMID:19820135

The Function of the Mitochondrial Calcium Uniporter in Neurodegenerative Disorders

PubMed Central

Liao, Yajin; Dong, Yuan; Cheng, Jinbo

2017-01-01

The mitochondrial calcium uniporter (MCU)—a calcium uniporter on the inner membrane of mitochondria—controls the mitochondrial calcium uptake in normal and abnormal situations. Mitochondrial calcium is essential for the production of adenosine triphosphate (ATP); however, excessive calcium will induce mitochondrial dysfunction. Calcium homeostasis disruption and mitochondrial dysfunction is observed in many neurodegenerative disorders. However, the role and regulatory mechanism of the MCU in the development of these diseases are obscure. In this review, we summarize the role of the MCU in controlling oxidative stress-elevated mitochondrial calcium and its function in neurodegenerative disorders. Inhibition of the MCU signaling pathway might be a new target for the treatment of neurodegenerative disorders. PMID:28208618

21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as safe...

Effect of calcium chloride treatments on calcium content, anthracnose severity and antioxidant activity in papaya fruit during ambient storage.

PubMed

Madani, Babak; Mirshekari, Amin; Yahia, Elhadi

2016-07-01

There have been no reports on the effects of preharvest calcium application on anthracnose disease severity, antioxidant activity and cellular changes during ambient storage of papaya, and therefore the objective of this study was to investigate these effects. Higher calcium concentrations (1.5 and 2% w/v) increased calcium concentration in the peel and pulp tissues, maintained firmness, and reduced anthracnose incidence and severity. While leakage of calcium-treated fruit was lower for 1.5 and 2% calcium treatments compared to the control, microscopic results confirmed that pulp cell wall thickness was higher after 6 days in storage, for the 2% calcium treatment compared to the control. Calcium-treated fruit also had higher total antioxidant activity and total phenolic compounds during storage. Calcium chloride, especially at higher concentrations, is effective in maintaining papaya fruit quality during ambient storage. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

A Double-Blind Randomized Placebo Controlled Trial of Magnesium Oxide for Alleviation of Chronic Low Back Pain

DTIC Science & Technology

1999-01-01

minireview of the interactions between calcium channel blockers and analgesics. In a metaanalysis of several studies, they concluded that calcium ...Philadelphia: W. B. Saunders Company. Miranda, H., & Paeile, C. (1990). Interactions between analgesics and calcium channel blockers. General... calcium access into the cell and the actions of calcium inside the cell. The influx of calcium inside the depolarized presynaptic cell allows for

Direct Inhibitory Effect of Hypercalcemia on Renal Actions of Parathyroid Hormone

PubMed Central

Beck, Nama; Singh, Harbans; Reed, Sarah W.; Davis, Bernard B.

1974-01-01

The effects of calcium on the renal actions of parathyroid hormone (PTH) were studied in vivo and in vitro. In parathyroidectomized rats, variable levels of blood calcium concentration were induced by intravenous infusion of calcium. The renal responses to the injected PTH, i.e. phosphate and cyclic AMP excretion, were compared in these animals. After PTH injection, the increases of both phosphate and cyclic AMP excretion were less in the calcium-infused animals than in the control group without calcium infusion. There was an inverse correlation between the renal responses to PTH and plasma calcium concentration of 4.2-13.5 mg/100 ml. But calcium had no effect on phosphate excretion induced by infusion of dibutyryl cyclic AMP. In the in vitro experiments, the increase of cyclic AMP concentration in response to PTH was less in renal cortical slices taken from the calcium-infused animals than in ones from the control group without calcium infusion. Calcium also inhibited the activation of renal cortical adenylate cyclase in response to PTH, but calcium had no effect on phosphodiesterase. The data indicate that calcium directly inhibits renal actions of PTH both in vivo and in vitro. Such inhibitory mechanism is probably at or before the step of PTH-dependent cyclic AMP generation in the kidney. PMID:4359938

Selective dopamine receptor 4 activation mediates the hippocampal neuronal calcium response via IP3 and ryanodine receptors.

PubMed

Wang, Ya-Li; Wang, Jian-Gang; Guo, Fang-Li; Gao, Xia-Huan; Zhao, Dan-Dan; Zhang, Lin; Wang, Jian-Zhi; Lu, Cheng-Biao

2017-09-01

Intracellular calcium is a key factor in most cellular processes, including cell growth, differentiation, proliferation and neurotransmitter release. Dopamine (DA) mediates synaptic transmission by regulating the intracellular calcium content. It is not clear, however, which specific subunit of the DA receptor contributes to DA modulation of intracellular calcium content changes. Through the traditional technique of Fura-2 calcium imaging, this study demonstrated that the DA can induce transient calcium in cultured hippocampal neurons and that this response can be mimicked by a selective dopamine receptor 4 (DR4) agonist PD168077 (PD). PD-induced calcium transience can be blocked by a calcium chelator, such as BAPTA-AM, or by pre-treatment of neurons with thapsigargin, a IP 3 receptor antagonist, or a micromolar concentration of ryanodine, a ryanodine receptor (RyR) antagonist. However PD-induced calcium transience cannot be blocked by pre-treatment of neurons with a free-calcium medium or a cocktail of NMDA receptor, L-type calcium channel and alpha7 nicotinic acetylcholine receptor blockers. These results indicate that the calcium response induced by DR4 activation is mainly through activation of IP 3 receptor in internal stores, which is likely to contribute to the DA modulation of synaptic transmission and cognitive function. Copyright © 2017. Published by Elsevier B.V.

Calcium Input Frequency, Duration and Amplitude Differentially Modulate the Relative Activation of Calcineurin and CaMKII

PubMed Central

Li, Lu; Stefan, Melanie I.; Le Novère, Nicolas

2012-01-01

NMDA receptor dependent long-term potentiation (LTP) and long-term depression (LTD) are two prominent forms of synaptic plasticity, both of which are triggered by post-synaptic calcium elevation. To understand how calcium selectively stimulates two opposing processes, we developed a detailed computational model and performed simulations with different calcium input frequencies, amplitudes, and durations. We show that with a total amount of calcium ions kept constant, high frequencies of calcium pulses stimulate calmodulin more efficiently. Calcium input activates both calcineurin and Ca2+/calmodulin-dependent protein kinase II (CaMKII) at all frequencies, but increased frequencies shift the relative activation from calcineurin to CaMKII. Irrespective of amplitude and duration of the inputs, the total amount of calcium ions injected adjusts the sensitivity of the system to calcium input frequencies. At a given frequency, the quantity of CaMKII activated is proportional to the total amount of calcium. Thus, an input of a small amount of calcium at high frequencies can induce the same activation of CaMKII as a larger amount, at lower frequencies. Finally, the extent of activation of CaMKII signals with high calcium frequency is further controlled by other factors, including the availability of calmodulin, and by the potency of phosphatase inhibitors. PMID:22962589

Calcium Intake, Major Dietary Sources and Bone Health Indicators in Iranian Primary School Children.

PubMed

Omidvar, Nasrin; Neyestani, Tirang-Reza; Hajifaraji, Majid; Eshraghian, Mohammad-Reza; Rezazadeh, Arezoo; Armin, Saloumeh; Haidari, Homa; Zowghi, Telma

2015-02-01

Adequate calcium intake may have a crucial role with regards to prevention of many chronic diseases, including hypertension, hypercholesterolemia, different types of cancer, obesity and osteoporosis. In children, sufficient calcium intake is especially important to support the accelerated growth spurt during the preteen and teenage years and to increase bone mineral mass to lay the foundation for older age. This study aimed to assess daily calcium intake in school-age children to ensure whether they fulfill the FGP dairy serving recommendations, the recommended levels of daily calcium intake and to assess the relationship between dietary calcium intake and major bone health indicators. A total of 501 Iranian school-age children were randomly selected. Calcium intake was assessed using a semi-quantitative food frequency questionnaire. Bone health indicators were also assessed. Dairy products contributed to 69.3% of the total calcium intake of the children. Daily adequate intake of calcium was achieved by 17.8% of children. Only 29.8% met the Food guide pyramid recommendations for dairy intake. Dietary calcium intake was not significantly correlated with serum calcium and other selected biochemical indicators of bone health. The need for planning appropriate nutrition strategies for overcoming inadequate calcium intake in school age children in the city of Tehran is inevitable.

Loperamide: A positive modulator for store-operated calcium channels?

PubMed Central

Harper, Jacquie L.; Shin, Yangmee; Daly, John W.

1997-01-01

The depletion of inositol trisphosphate-sensitive intracellular pools of calcium causes activation of store-operated calcium (SOC) channels. Loperamide at 10–30 μM has no effect on intracellular calcium levels alone, but augments calcium levels in cultured cells when SOC channels have been activated. In HL-60 leukemic cells, the apparent positive modulatory effect of loperamide on SOC channels occurs when these channels have been activated after ATP, thapsigargin, or ionomycin-elicited depletion of calcium from intracellular storage sites. Loperamide has no effect when levels of intracellular calcium are elevated through a mechanism not involving SOC channels by using sphingosine. Loperamide caused augmentation of intracellular calcium levels after activation of SOC channels in NIH 3T3 fibroblasts, astrocytoma 1321N cells, smooth muscle DDT-MF2 cells, RBL-2H3 mast cells, and pituitary GH4C1 cells. Only in astrocytoma cells did loperamide cause an elevation in intracellular calcium in the absence of activation of SOC channels. The augmentation of intracellular calcium elicited by loperamide in cultured cells was dependent on extracellular calcium and was somewhat resistant to agents (SKF 96365, miconazole, clotrimazole, nitrendipine, and trifluoperazine) that in the absence of loperamide effectively blocked SOC channels. It appears that loperamide augments influx of calcium through activated SOC channels. PMID:9405713

Vasopressin regulates renal calcium excretion in humans

PubMed Central

Hanouna, Guillaume; Haymann, Jean-Philippe; Baud, Laurent; Letavernier, Emmanuel

2015-01-01

Antidiuretic hormone or arginine vasopressin (AVP) increases water reabsorption in the collecting ducts of the kidney. Three decades ago, experimental models have shown that AVP may increase calcium reabsorption in rat kidney. The objective of this study was to assess whether AVP modulates renal calcium excretion in humans. We analyzed calcium, potassium, and sodium fractional excretion in eight patients affected by insipidus diabetes (nephrogenic or central) under acute vasopressin receptor agonist action and in 10 patients undergoing oral water load test affected or not by inappropriate antidiuretic hormone secretion (SIADH). Synthetic V2 receptor agonist (dDAVP) reduced significantly calcium fractional excretion from 1.71% to 0.58% (P < 0.05) in patients with central diabetes insipidus. In patients with nephrogenic diabetes insipidus (resistant to AVP), calcium fractional excretion did not change significantly after injection (0.48–0.68%, P = NS). In normal subjects undergoing oral water load test, calcium fractional excretion increased significantly from 1.02% to 2.54% (P < 0.05). Patients affected by SIADH had a high calcium fractional excretion at baseline that remained stable during test from 3.30% to 3.33% (P = NS), possibly resulting from a reduced calcium absorption in renal proximal tubule. In both groups, there was a significant correlation between urine output and calcium renal excretion. In humans, dDAVP decreases calcium fractional excretion in the short term. Conversely, water intake, which lowers AVP concentration, increases calcium fractional excretion. The correlation between urine output and calcium excretion suggests that AVP-related antidiuresis increases calcium reabsorption in collecting ducts. PMID:26620256

Calcium Carbonate

MedlinePlus

... Maalox® (as a combination product containing Calcium Carbonate, Simethicone) ... Relief (as a combination product containing Calcium Carbonate, Simethicone) ... Plus (as a combination product containing Calcium Carbonate, Simethicone)

Determining attitudinal and behavioral factors concerning milk and dairy intake and their association with calcium intake in college students.

PubMed

Rose, Angela M; Williams, Rachel A; Rengers, Brooke; Kennel, Julie A; Gunther, Carolyn

2018-04-01

Average intake of calcium among college students is below the recommended intake, and knowledge surrounding the attitudinal and behavioral factors that influence milk and dairy intake, a primary food source of calcium, is limited. The purpose of this study was to evaluate college students' attitudes and behaviors concerning milk and dairy consumption and their association with calcium intake. Participants were 1,730 undergraduate students who completed an online survey (SurveyMonkey) as part of baseline data collection for a social marketing dairy campaign. The online survey assessed attitudes and behaviors concerning milk and dairy intake, and calcium intake. Questions about milk- and dairy-related attitudes and behaviors were grouped into 14 factors using factor analysis. Predictors of calcium intake were then evaluated. Median calcium intake across all participants was 928.6 mg/day, with males consuming higher calcium intakes than females ( P < 0.001). Adjusted for gender, calcium intakes were most strongly (and positively) correlated with associating milk with specific eating occasions and availability (i.e., storing calcium-rich foods in one's dorm or apartment) (both P < 0.001). Other correlates of calcium intake included: positive-viewing milk as healthy ( P = 0.039), having family members who drink milk) ( P = 0.039), and taking calcium supplements ( P = 0.056); and negative-parent rules concerning milk ( P = 0.031) and viewing milk in dining halls negatively ( P = 0.05). Calcium intakes among college students enrolled in the current study was below the recommended dietary allowance of 1,000 mg/day, reinforcing the need for dietary interventions in this target population, especially females. Practitioners and researchers should consider the factors found here to impact calcium intake, particularly associating milk with specific eating occasions (e.g., milk with breakfast) and having calcium-rich foods available in the dorm room or apartment, as intervention strategies in future efforts aimed at promoting milk and dairy foods and beverages for improved calcium intake in college students.

Regional citrate anticoagulation in hemodialysis: an observational study of safety, efficacy, and effect on calcium balance during routine care.

PubMed

Singer, Richard F; Williams, Oliver; Mercado, Chari; Chen, Bonny; Talaulikar, Girish; Walters, Giles; Roberts, Darren M

2016-01-01

Regional citrate hemodialysis anticoagulation is used when heparin is contraindicated, but most protocols require large infusions of calcium and frequent intradialytic plasma ionized calcium measurements. The objective of this study was to determine the safety, efficacy, and effect on calcium balance of regional citrate anticoagulation using sparse plasma ionized calcium sampling. The design of this study was observational. The setting of this study was the hospital hemodialysis center. The subjects of this study were the hospital hemodialysis patients. Dialysate calcium concentration by atomic absorption spectroscopy and total dialysate weight were used as measurements. Regional citrate anticoagulation was introduced using zero calcium dialysate, pre-dialyzer citrate infusion, and post-dialyzer calcium infusion. Infusions were adjusted based on pre- and post-dialyzer calcium measurements obtained at least twice during a 4-h dialysis. The protocol was simplified after the first 357 sessions to dispense with post-dialyzer calcium measurements. Heparin-anticoagulated sessions were performed using acetate-acidified 1.25 mmol/L calcium or citrate-acidified 1.5 mmol/L calcium dialysate. Calcium balance assessment was by complete dialysate recovery. Safety and efficacy were assessed prospectively using a point-of-care database to record ionized calcium and clinical events. Groups were compared using t test, ANOVA, Wilcoxon rank sum, or Kruskal-Wallis as appropriate. Seventy-five patients received regional citrate-anticoagulated dialysis over 1051 dialysis sessions. Of these, 357 dialysis sessions were performed using the original citrate anticoagulation protocol and 694 using the simplified protocol. Dialysis was effective and safe. Only 3 dialyzers clotted; 1 patient suffered symptomatic hypercalcemia and none suffered symptomatic hypocalcemia. Calcium balance was assessed in 15 regional citrate-anticoagulated dialysis sessions and 30 heparin-anticoagulated sessions. The median calcium loss was 0.8 mmol/h dialyzed in both groups (p = 0.43), and end of treatment ionized calcium was the same in both groups (1.07 ± 0.04 mmol/L). Our findings for calcium balance, efficacy, and safety are valid only for the protocol studied, which excluded patient with severe liver dysfunction. Regional citrate dialysis can be performed safely and effectively using a sparse plasma calcium sampling protocol. The calcium balance induced by this protocol is not different to that seen in standard heparin-anticoagulated dialysis, but in the absence of prospective studies, it is unknown whether this is optimal for patient care.

Similar calcium status is present in infants fed formula with and without prebiotics

USDA-ARS?s Scientific Manuscript database

Prebiotic oligosaccharides can increase calcium absorption in adolescents and adults. Whether they affect calcium absorption in infants has not been assessed. Few data are available to compare the calcium status of infants fed modern infant formulas to that of breast fed infants. To evaluate calcium...

Calcium and vitamin D for bone health in adults

USDA-ARS?s Scientific Manuscript database

The calcium intake requirement is challenging to determine, and the IOM recommendations are based largely on calcium balance studies. The IOM recommends a calcium intake of 1000-1200 mg per day for older adults to support the preservation of bone mass. Food sources of calcium are preferred because h...

Bioavailability of enteric-coated microencapsulated calcium during pregnancy: A randomized crossover trial in Bangladesh

USDA-ARS?s Scientific Manuscript database

Prenatal calcium and iron supplements are recommended in settings of low dietary calcium intake and high prevalence of anemia. However, calcium administration may inhibit iron absorption. To overcome calcium-iron interactions, we developed a multi-micronutrient powder containing iron (60 mg), folic ...

21 CFR 172.720 - Calcium lactobionate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium lactobionate. 172.720 Section 172.720 Food... Other Specific Usage Additives § 172.720 Calcium lactobionate. The food additive calcium lactobionate... additive is the calcium salt of lactobionic acid (4-(β,D-galactosido)-D-gluconic acid) produced by the...

21 CFR 172.720 - Calcium lactobionate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium lactobionate. 172.720 Section 172.720 Food... Other Specific Usage Additives § 172.720 Calcium lactobionate. The food additive calcium lactobionate... additive is the calcium salt of lactobionic acid (4-(β,D-galactosido)-D-gluconic acid) produced by the...

21 CFR 172.410 - Calcium silicate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely...

21 CFR 172.410 - Calcium silicate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely...

21 CFR 172.410 - Calcium silicate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely...

21 CFR 172.410 - Calcium silicate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely...

21 CFR 172.410 - Calcium silicate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium silicate. 172.410 Section 172.410 Food and... PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Anticaking Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used in food in accordance with the...

On the structure of amorphous calcium carbonate--a detailed study by solid-state NMR spectroscopy.

PubMed

Nebel, Holger; Neumann, Markus; Mayer, Christian; Epple, Matthias

2008-09-01

The calcium carbonate phases calcite, aragonite, vaterite, monohydrocalcite (calcium carbonate monohydrate), and ikaite (calcium carbonate hexahydrate) were studied by solid-state NMR spectroscopy ( (1)H and (13)C). Further model compounds were sodium hydrogencarbonate, potassium hydrogencarbonate, and calcium hydroxide. With the help of these data, the structure of synthetically prepared additive-free amorphous calcium carbonate (ACC) was analyzed. ACC contains molecular water (as H 2O), a small amount of mobile hydroxide, and no hydrogencarbonate. This supports the concept of ACC as a transient precursor in the formation of calcium carbonate biominerals.

The calcium paradox - What should we have to fear?

PubMed Central

de Oliveira, Marcos Aurélio Barboza; Brandi, Antônio Carlos; dos Santos, Carlos Alberto; Botelho, Paulo Henrique Husseni; Cortez, José Luís Lasso; Goissis, Gilberto; Braile, Domingo Marcolino

2014-01-01

The calcium paradox was first mentioned in 1966 by Zimmerman et al. Thereafter gained great interest from the scientific community due to the fact of the absence of calcium ions in heart muscle cells produce damage similar to ischemia-reperfusion. Although not all known mechanisms involved in cellular injury in the calcium paradox intercellular connection maintained only by nexus seems to have a key role in cellular fragmentation. The addition of small concentrations of calcium, calcium channel blockers, and hyponatraemia hypothermia are important to prevent any cellular damage during reperfusion solutions with physiological concentration of calcium. PMID:25140476

Lattice model for calcium dynamics

NASA Astrophysics Data System (ADS)

Guisoni, Nara; de Oliveira, Mario José

2005-06-01

We present a simplified lattice model to study calcium dynamics in the endoplasmic reticulum membrane. Calcium channels and calcium ions are placed in two interpenetrating square lattices which are connected in two ways: (i) via calcium release and (ii) because transitions between channel states are calcium dependent. The opening or closing of a channel is a stochastic process controlled by two functions which depend on the calcium density on the channel neighborhood. The model is studied through mean field calculations and simulations. We show that the critical behavior of the model changes drastically depending on the opening/closing functions. For certain choices of these functions, all channels are closed at very low and high calcium densities and the model presents one absorbing state.

Signaling complexes of voltage-gated calcium channels

PubMed Central

Turner, Ray W; Anderson, Dustin

2011-01-01

Voltage-gated calcium channels are key mediators of depolarization induced calcium entry into electrically excitable cells. There is increasing evidence that voltage-gated calcium channels, like many other types of ionic channels, do not operate in isolation, but instead form complexes with signaling molecules, G protein coupled receptors, and other types of ion channels. Furthermore, there appears to be bidirectional signaling within these protein complexes, thus allowing not only for efficient translation of calcium signals into cellular responses, but also for tight control of calcium entry per se. In this review, we will focus predominantly on signaling complexes between G protein-coupled receptors and high voltage activated calcium channels, and on complexes of voltage-gated calcium channels and members of the potassium channel superfamily. PMID:21832880

Interactions of Mitochondria/Metabolism and Calcium Regulation in Alzheimer’s Disease - A Calcinist Point of View

PubMed Central

Gibson, Gary E.; Thakkar, Ankita

2017-01-01

Decades of research suggest that alterations in calcium are central to the pathophysiology of Alzheimer’s Disease (AD). Highly reproducible changes in calcium dynamics occur in cells from patients with both genetic and non-genetic forms of AD relative to controls. The most robust change is an exaggerated release of calcium from internal stores. Detailed analysis of these changes in animal and cell models of the AD-causing presenilin mutations reveal robust changes in ryanodine receptors, inositol tris-phosphate receptors, calcium leak channels and store activated calcium entry. Similar anomalies in calcium result when AD-like changes in mitochondrial enzymes or oxidative stress are induced experimentally. The calcium abnormalities can be directly linked to the altered tau phosphorylation, amyloid precursor protein processing and synaptic dysfunction that are defining features of AD. A better understanding of these changes is required before using calcium abnormalities as therapeutic targets. PMID:28181072

Interactions of Mitochondria/Metabolism and Calcium Regulation in Alzheimer's Disease: A Calcinist Point of View.

PubMed

Gibson, Gary E; Thakkar, Ankita

2017-06-01

Decades of research suggest that alterations in calcium are central to the pathophysiology of Alzheimer's Disease (AD). Highly reproducible changes in calcium dynamics occur in cells from patients with both genetic and non-genetic forms of AD relative to controls. The most robust change is an exaggerated release of calcium from internal stores. Detailed analysis of these changes in animal and cell models of the AD-causing presenilin mutations reveal robust changes in ryanodine receptors, inositol tris-phosphate receptors, calcium leak channels and store activated calcium entry. Similar anomalies in calcium result when AD-like changes in mitochondrial enzymes or oxidative stress are induced experimentally. The calcium abnormalities can be directly linked to the altered tau phosphorylation, amyloid precursor protein processing and synaptic dysfunction that are defining features of AD. A better understanding of these changes is required before using calcium abnormalities as therapeutic targets.

Calcium mobilization in HeLa cells induced by nitric oxide.

PubMed

Huang, Yimei; Zheng, Liqin; Yang, Hongqin; Chen, Jiangxu; Wang, Yuhua; Li, Hui; Xie, Shusen

2014-01-01

Nitric oxide (NO) has been proposed to be involved in tumor growth and metastasis. However, the mechanism by which nitric oxide modulates cancer cell growth and metastasis on cellular and molecular level is still not fully understood. This work utilized confocal microscopy and fluorescence microplate reader to investigate the effects of exogenous NO on the mobilization of calcium, which is one of the regulators of cell migration, in HeLa cells. The results show that NO elevates calcium in concentration-dependent manner in HeLa cells. And the elevation of calcium induced by NO is due to calcium influx and calcium release from intracellular calcium stores. Moreover, calcium release from intracellular stores is dominant. Furthermore, calcium release from mitochondria is one of the modulation pathways of NO. These findings would contribute to recognizing the significance of NO in cancer cell proliferation and metastasis. © Wiley Periodicals, Inc.

Monitoring Endoplasmic Reticulum Calcium Homeostasis Using a Gaussia Luciferase SERCaMP.

PubMed

Henderson, Mark J; Wires, Emily S; Trychta, Kathleen A; Yan, Xiaokang; Harvey, Brandon K

2015-09-06

The endoplasmic reticulum (ER) contains the highest level of intracellular calcium, with concentrations approximately 5,000-fold greater than cytoplasmic levels. Tight control over ER calcium is imperative for protein folding, modification and trafficking. Perturbations to ER calcium can result in the activation of the unfolded protein response, a three-prong ER stress response mechanism, and contribute to pathogenesis in a variety of diseases. The ability to monitor ER calcium alterations during disease onset and progression is important in principle, yet challenging in practice. Currently available methods for monitoring ER calcium, such as calcium-dependent fluorescent dyes and proteins, have provided insight into ER calcium dynamics in cells, however these tools are not well suited for in vivo studies. Our lab has demonstrated that a modification to the carboxy-terminus of Gaussia luciferase confers secretion of the reporter in response to ER calcium depletion. The methods for using a luciferase based, secreted ER calcium monitoring protein (SERCaMP) for in vitro and in vivo applications are described herein. This video highlights hepatic injections, pharmacological manipulation of GLuc-SERCaMP, blood collection and processing, and assay parameters for longitudinal monitoring of ER calcium.

Effect of calcium on the hemolytic activity of Stichodactyla helianthus toxin sticholysin II on human erythrocytes.

PubMed

Celedón, Gloria; González, Gustavo; Lissi, Eduardo; Cerda, Tania; Martinez, Diana; Soto, Carmen; Pupo, Mario; Pazos, Fabiola; Lanio, Maria E; Alvarez, Carlos

2009-11-01

Sticholysin II (St II) is a toxin from the sea anemona Stichodactyla helianthus that produces erythrocytes lysis at low concentration and its activity depends on the presence of calcium. Calcium may act modifying toxin interaction with erythrocyte membranes or activating cellular processes which may result in a modified St II lytic action. In this study we are reporting that, in the presence of external K(+), extracellular calcium decreased St II activity on erythrocytes. On the other hand an increase of intracellular calcium promotes Sty II lytic activity. The effect of intracellular calcium was specifically studied in relation to membrane lipid translocation elicited by scramblases and how this action influence St II lytic activity on erythrocytes. We used 0.5 mmol/L calcium and 10 mmol/L A23187, as calcium ionophore, for scramblases activation and found increased St II activity associated to increase of intracellular calcium. N-ethyl maleimide (activator) and 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (inhibitor) were used as scramblases modulators in the assays which produced an increase and a decrease of the calcium effect, respectively. Results reported suggest an improved St II membrane pore-forming capacity promoted by intracellular calcium associated to membrane phospholipids translocation.

Association between calcium ingested from drinking water and femoral bone density in elderly women: evidence from the EPIDOS cohort.

PubMed

Aptel, I; Cance-Rouzaud, A; Grandjean, H

1999-05-01

Although the main source of dietary calcium is dairy products, the calcium contained in mineral water, which is as available as that of milk, could provide a valuable source of calcium. We analyzed the data from the EPIDOS multicenter study to evaluate the relationship between both dietary calcium and that supplied by drinking water and bone density measured at the femoral neck by dual-energy X-ray absorptiometry. The study included 4434 women over 75 years of age who had not received any treatment likely to interfere with calcium metabolism. A significant correlation was found between total calcium intake and bone density at the femoral neck (r = 0.10, p < 0. 001). After adjustment for the main variables influencing bone density, an increase of 100 mg/day in calcium from drinking water was associated to a 0.5% increase in femoral bone density, while a similar increase in dietary calcium from other sources only led to a 0.2% increase; however, this difference was not significant. The consumption of calcium-rich mineral water may be of interest, especially in older women who consume little calcium from dairy products.

The role of calcium intake in preventing bone fragility, hypertension, and certain cancers.

PubMed

Barger-Lux, M J; Heaney, R P

1994-08-01

This paper examines the evidence that connects calcium intake and vitamin D status to bone fragility, hypertension, colon cancer, and breast cancer. Human calcium physiology, with an intestinal absorptive barrier and inefficient conservation, reflects the abundance of calcium in the primordial human food supply. The calcium intake of stone-age adults is estimated at 50 to 75 mmol/d, three to five times the median calcium intake of present-day U.S. adults. Long-term calcium restriction and/or insufficient vitamin D may promote the development of bone fragility, high blood pressure, colon cancer, and breast cancer in susceptible individuals. Conversely, improvement in calcium intake and/or in vitamin D status may help to prevent these serious health problems. At least 12 intervention studies have established the skeletal benefit of increased calcium intake among women in the late postmenopause. Other reports suggest that adequate calcium may protect against salt-sensitive and pregnancy-associated hypertension. High intakes of both dietary calcium and vitamin D are associated with reduced development of precancerous changes in colonic mucosa. Preliminary findings also suggest that vitamin D has a protective effect against breast cancer.

Calcium ion binding to a soil fulvic acid using a donnan potential model

USGS Publications Warehouse

Marinsky, J.A.; Mathuthu, A.; Ephraim, J.H.; Reddy, M.M.

1999-01-01

Calcium ion binding to a soil fulvic acid (Armadale Bh Horizon) was evaluated over a range of calcium ion concentrations, from pH 3.8 to 7.3, using potentiometric titrations and calcium ion electrode measurements. Fulvic acid concentration was constant (100 milligrams per liter) and calcium ion concentration varied up to 8 X 10-4 moles per liter. Experiments discussed here included: (1) titrations of fulvic acid-calcium ion containing solutions with sodium hydroxide; and (2) titrations of fully neutralized fulvic acid with calcium chloride solutions. Apparent binding constants (expressed as the logarithm of the value, log ??app) vary with solution pH, calcium ion concentration, degree of acid dissociation, and ionic strength (from log ??app = 2.5 to 3.9) and are similar to those reported by others. Fulvic acid charge, and the associated Donnan Potential, influences calcium ion-fulvic acid ion pair formation. A Donnan Potential corrrection term allowed calculation of intrinsic calcium ion-fulvic acid binding constants. Intrinsic binding constants vary from 1.2 to 2.5 (the average value is about log??= 1.6) and are similar to, but somewhat higher than, stability constants for calcium ion-carboxylic acid monodentate complexes. ?? by Oldenbourg Wissenschaftsverlag, Mu??nchen.

Calcium supplementation and cardiovascular risk: A rising concern.

PubMed

Tankeu, Aurel T; Ndip Agbor, Valirie; Noubiap, Jean Jacques

2017-06-01

Over the past decade, the number of individuals taking calcium supplementation worldwide has been on the rise, especially with the emergence of new pharmaceutical companies specialized in the marketing of dietary supplements; with calcium supplementation being their main business axis. This is mostly because of the established role of calcium in the prevention and treatment of osteoporosis and, to a lesser extent, its role in the prevention of fractures. Recently, a rising body of evidence on the adverse effect of calcium supplementation on nonskeletal, especially cardiovascular, health has been a cause for concern. In fact, a significant number of studies have reported an association between calcium supplementation and adverse cardiovascular events, even though high dietary calcium intake was shown to have a protective effect. The mechanism by which calcium supplementation could cause a cardiovascular event was still unclear until a recent study published in the Journal of the American Heart Association. Combining this recent finding with available data associating calcium supplementation with cardiovascular mortality and all-cause mortality, we call on the need for an evidence-based approach to calcium supplementation, while stressing on the safety of dietary calcium intake over the former on cardiovascular health. ©2017 Wiley Periodicals, Inc.

Conversion of alkali metal sulfate to the carbonate

DOEpatents

Sheth, Atul C.

1982-01-01

A process for converting potassium sulfate to potassium carbonate in which a mixture of potassium sulfate and calcium oxide are reacted at a temperature in the range of between about 700.degree. C. and about 800.degree. C. with a gaseous mixture having a minor amount of hydrogen and/or carbon monoxide in a diluent with the calcium oxide being present in an amount not greater than about 20 percent by weight of the potassium sulfate to produce an aqueous mixture of potassium sulfide, potassium bisulfide, potassium hydroxide and calcium sulfide and a gaseous mixture of steam and hydrogen sulfide. The potassium and calcium salts are quenched to produce an aqueous slurry of soluble potassium salts and insoluble calcium salts and a gaseous mixture of steam and hydrogen sulfide. The insoluble calcium salts are then separated from the aqueous solution of soluble potassium salts. The calcium salts are dried to produce calcium sulfide, calcium bisulfide and steam, and then, the calcium sulfide and calcium bisulfide are converted to the oxide and recycled. The soluble potassium salts are carbonated to produce potassium carbonate which is concentrated and the precipitated crystals separated. The sulfur-containing compounds are further treated.

Calcium-pH crosstalks in rat mast cells: cytosolic alkalinization, but not intracellular calcium release, is a sufficient signal for degranulation

PubMed Central

Alfonso, A; Cabado, A G; Vieytes, M R; Botana, L M

2000-01-01

The aim of this work was to study the relationship between intracellular alkalinization, calcium fluxes and histamine release in rat mast cells. Intracellular alkalinization was induced by nigericin, a monovalent cation ionophore, and by NH4Cl (ammonium chloride). Calcium cytosolic and intracellular pH were measured by fluorescence digital imaging using Fura-2-AM and BCECF-AM.In rat mast cells, nigericin and NH4Cl induce a dose-dependent intracellular alkalinization, a dose-dependent increase in intracellular calcium levels by releasing calcium from intracellular pools, and an activation of capacitative calcium influx.The increase in both intracellular calcium and pH activates exocytosis (histamine release) in the absence of external calcium. Under the same conditions, thapsigargin does not activate exocytosis, the main difference being that thapsigargin does not alkalinize the cytosol.After alkalinization, histamine release is intracellular-calcium dependent. With 2.5 mM EGTA and thapsigargin the cell response decreases by 62%.The cytosolic alkalinization, in addition to the calcium increase it is enough signal to elicit the exocytotic process in rat mast cells. PMID:10952669

Subcellular localization of calcium deposits in the noble crayfish Astacus astacus spermatophore: Implications for post-mating spermatophore hardening and spermatozoon maturation.

PubMed

Niksirat, Hamid; Kouba, Antonín

2016-04-01

The freshly ejaculated spermatophore of crayfish undergoes a hardening process during post-mating storage on the body surface of female. The ultrastructural distribution of calcium deposits were studied and compared in freshly ejaculated and post-mating noble crayfish spermatophores, using the oxalate-pyroantimonate technique, to determine possible roles of calcium in post-mating spermatophore hardening and spermatozoon maturation. Small particles of sparsely distributed calcium deposits were visible in the wall of freshly ejaculated spermatophore. Also, large amount of calcium deposits were visible in the membranes of the freshly ejaculated spermatozoon. Five minutes post-ejaculation, granules in the spermatophore wall appeared as porous formations with numerous electron lucent spaces. Calcium deposits were visible within the spaces and scattered in the spermatophore wall matrix, where smaller calcium deposits combined to form globular calcium deposits. Large numbers of the globular calcium deposits were visible in the wall of the post-mating spermatophore. Smaller calcium deposits were detected in the central area of post-mating spermatophore, which contains the sperm mass, and in the extracellular matrix and capsule. While the density of calcium deposits decreased in the post-mating spermatozoon membranes, numerous small calcium deposits appeared in the subacrosomal zone and nucleus. Substantial changes in calcium deposit distribution in the crayfish spermatophore during post-mating storage on the body of female may be involved in the processes of the spermatophore hardening and spermatozoon maturation. © 2016 Wiley Periodicals, Inc.

Normocalcemia is maintained in mice under conditions of calcium malabsorption by vitamin D–induced inhibition of bone mineralization

PubMed Central

Lieben, Liesbet; Masuyama, Ritsuko; Torrekens, Sophie; Van Looveren, Riet; Schrooten, Jan; Baatsen, Pieter; Lafage-Proust, Marie-Hélène; Dresselaers, Tom; Feng, Jian Q.; Bonewald, Lynda F.; Meyer, Mark B.; Pike, J. Wesley; Bouillon, Roger; Carmeliet, Geert

2012-01-01

Serum calcium levels are tightly controlled by an integrated hormone-controlled system that involves active vitamin D [1,25(OH)2D], which can elicit calcium mobilization from bone when intestinal calcium absorption is decreased. The skeletal adaptations, however, are still poorly characterized. To gain insight into these issues, we analyzed the consequences of specific vitamin D receptor (Vdr) inactivation in the intestine and in mature osteoblasts on calcium and bone homeostasis. We report here that decreased intestinal calcium absorption in intestine-specific Vdr knockout mice resulted in severely reduced skeletal calcium levels so as to ensure normal levels of calcium in the serum. Furthermore, increased 1,25(OH)2D levels not only stimulated bone turnover, leading to osteopenia, but also suppressed bone matrix mineralization. This resulted in extensive hyperosteoidosis, also surrounding the osteocytes, and hypomineralization of the entire bone cortex, which may have contributed to the increase in bone fractures. Mechanistically, osteoblastic VDR signaling suppressed calcium incorporation in bone by directly stimulating the transcription of genes encoding mineralization inhibitors. Ablation of skeletal Vdr signaling precluded this calcium transfer from bone to serum, leading to better preservation of bone mass and mineralization. These findings indicate that in mice, maintaining normocalcemia has priority over skeletal integrity, and that to minimize skeletal calcium storage, 1,25(OH)2D not only increases calcium release from bone, but also inhibits calcium incorporation in bone. PMID:22523068

Calcium requirements for Asian children and adolescents.

PubMed

Lee, Warren Tak Keung; Jiang, Ji

2008-01-01

Calcium is important for bone health. Over the last 15 years, reference calcium intakes in Western countries have been revised upwards for maximizing bone mass at skeletal maturity and for prevention of osteoporotic fractures. Some of these reference figures have also been adopted for use in Asian countries. However, the scientific data based on for revising reference calcium intakes in the West was largely based on Caucasians. Limited human studies relating to calcium requirements and bone mineralization have been conducted in Asians in Asia. In children and adolescents, a trial has confirmed no effects of calcium supplementation on bone gains in adolescent girls after 7 years. A meta-analysis has also revealed that calcium supplementation has little beneficial effects on bone gain. Given that genetic factors, hormonal status, body size, bone structure, diets, physical activity, vitamin D status and adaptation could modify calcium retention and bone integrity, these factors need to be considered collectively to promote bone health in Asian populations. Furthermore, studies to identify indigenous foods rich in calcium and high in bioavailability are needed to widen sources of dietary calcium. Ethnic differences in calcium retention, hormonal status, bone structure, bone mineral accretion and peak bone mass are evident among Asians, Caucasians and Blacks in USA. Hence, reference calcium intakes for Asians are likely to be unique and different from those of Caucasians. More research has to be conducted in Asian populations in order to develop appropriate reference calcium intakes for the region.

Effect of Oestrogen on Altering the Serum and Urinary Levels of Calcium, Phosphate and Magnesium in Hysterectomised Women Compared to Natural Menopausal South Indian Women: A Case Control Study.

PubMed

Sonu, Yeldose; Avinash, S S; Sreekantha; Arun Kumar, K; Malathi, M; Shivashankara, A R

2016-07-01

Given the paucity of studies conducted to know the effect of suddenness and earlier onset of endocrinological changes associated with hysterectomy, on the serum and urinary levels of calcium, magnesium and phosphate the present study was conducted to compare the levels of calcium, magnesium and phosphate in serum and urine of hysterectomised and natural menopausal south Indian women. This is a cross-sectional observational study. The study included three groups of 30 healthy premenopausal, 30 early surgical menopausal and 30 natural post menopausal women. Women suffering from any endocrine disease were excluded. Analysis was performed in serum and urine sample. The levels of calcium, magnesium and phosphate in serum and calcium/creatinine, magnesium/creatinine and phosphate/creatinine ratio were estimated in urine by spectrophotometric method. Hysterectomised women (serum calcium: 8.7 ± 0.09 mg/dl; urine calcium/creatinine: 0.16 ± 0.02) have significantly low serum calcium (p < 0.001) and high urinary calcium/creatinine (p = 0.002) ratio and post menopausal women (serum magnesium: 2.1 ± 0.03; serum phosphate: 4.4 ± 0.16; urinary calcium/creatinine: 0.17 ± 0.02; urinary magnesium/creatinine: 0.09 ± 0.01) have significantly high serum magnesium (p = 0.016), serum phosphate (p = 0.043) and high urinary calcium/creatinine (p = 0.002), magnesium/creatinine ratio (p = 0.025) compared to healthy pre menopausal women. Post menopausal women (serum calcium: 9.1 ± 0.08) have significantly high serum calcium and phosphate compared to hysterectomised women (serum phosphate: 3.93 ± 0.11). Hysterectomised women have significantly low serum calcium, oestrogen and high urinary calcium/creatinine ratio compared to healthy premenopausal women and low serum calcium and low serum phosphate compared to natural postmenopausal women. Natural postmenopausal women had low serum oestrogen and high serum magnesium, serum phosphate, urinary calcium creatinine ratio and urinary magnesium creatinine ratio compared to healthy premenopausal women.

Effects of inorganic phosphate and ADP on calcium handling by the sarcoplasmic reticulum in rat skinned cardiac muscles.

PubMed

Xiang, J Z; Kentish, J C

1995-03-01

The aim was to investigate whether, and how, increases in inorganic phosphate (Pi) and ADP, similar to those occurring intracellularly during early myocardial ischaemia, affect the calcium handling of the sarcoplasmic reticulum. Rat ventricular trabeculae were permeabilised with saponin. The physiological process of calcium induced calcium release (CICR) from the muscle sarcoplasmic reticulum was triggered via flash photolysis of the "caged Ca2+", nitr-5. Alternatively, calcium release was induced by rapid application of caffeine to give an estimate of sarcoplasmic reticular calcium loading. The initial rate of sarcoplasmic reticular calcium pumping was also assessed by photolysis of caged ATP at saturating [Ca2+]. Myoplasmic [Ca2+] (using fluo-3) and isometric force were measured. Pi (2-20 mM) significantly depressed the magnitude of CICR and the associated force transient. Sarcoplasmic reticular calcium loading was inhibited even more than CICR by Pi, suggesting that reduced calcium loading could account for all of the inhibitory effect of Pi on CICR and that Pi may slightly activate the calcium release mechanism. The reduced sarcoplasmic reticular calcium loading seemed to be due to a fall in the free energy of ATP hydrolysis (delta GATP) available for the calcium pump, since equal decreases in delta GATP produced by adding both Pi and ADP in various ratios caused similar falls in the calcium loading of the sarcoplasmic reticulum. The caged ATP experiments indicated that Pi (20 mM) did not affect the rate constant of sarcoplasmic reticular calcium uptake. ADP (10 mM) alone, or with 1 mM Pi, inhibited calcium loading. In spite of this, ADP (10 mM) did not alter CICR and, when 1 mM Pi was added, ADP increased CICR above control. An increase in intracellular Pi reduces sarcoplasmic reticular calcium loading and thus depresses the CICR. This could be an important contributing factor in the hypoxic or ischaemic contractile failure of the myocardium. However the detrimental effect of Pi may be offset to some extent by a stimulatory action of ADP on the calcium release mechanism of CICR.

Neurotransmitter Release Can Be Stabilized by a Mechanism That Prevents Voltage Changes Near the End of Action Potentials from Affecting Calcium Currents

PubMed Central

Clarke, Stephen G.; Scarnati, Matthew S.

2016-01-01

At chemical synapses, presynaptic action potentials (APs) activate voltage-gated calcium channels, allowing calcium to enter and trigger neurotransmitter release. The duration, peak amplitude, and shape of the AP falling phase alter calcium entry, which can affect neurotransmitter release significantly. In many neurons, APs do not immediately return to the resting potential, but instead exhibit a period of depolarization or hyperpolarization referred to as an afterpotential. We hypothesized that presynaptic afterpotentials should alter neurotransmitter release by affecting the electrical driving force for calcium entry and calcium channel gating. In support of this, presynaptic calcium entry is affected by afterpotentials after standard instant voltage jumps. Here, we used the mouse calyx of Held synapse, which allows simultaneous presynaptic and postsynaptic patch-clamp recording, to show that the postsynaptic response is affected significantly by presynaptic afterpotentials after voltage jumps. We therefore tested the effects of presynaptic afterpotentials using simultaneous presynaptic and postsynaptic recordings and AP waveforms or real APs. Surprisingly, presynaptic afterpotentials after AP stimuli did not alter calcium channel responses or neurotransmitter release appreciably. We show that the AP repolarization time course causes afterpotential-induced changes in calcium driving force and changes in calcium channel gating to effectively cancel each other out. This mechanism, in which electrical driving force is balanced by channel gating, prevents changes in calcium influx from occurring at the end of the AP and therefore acts to stabilize synaptic transmission. In addition, this mechanism can act to stabilize neurotransmitter release when the presynaptic resting potential changes. SIGNIFICANCE STATEMENT The shape of presynaptic action potentials (APs), particularly the falling phase, affects calcium entry and small changes in calcium influx can produce large changes in postsynaptic responses. We hypothesized that afterpotentials, which often follow APs, affect calcium entry and neurotransmitter release. We tested this in calyx of Held nerve terminals, which allow simultaneous recording of presynaptic calcium currents and postsynaptic responses. Surprisingly, presynaptic afterpotentials did not alter calcium current or neurotransmitter release. We show that the AP falling phase causes afterpotential-induced changes in electrical driving force and calcium channel gating to cancel each other out. This mechanism regulates calcium entry at the end of APs and therefore stabilizes synaptic transmission. This also stabilizes responses when the presynaptic resting potential changes. PMID:27911759

Neurotransmitter Release Can Be Stabilized by a Mechanism That Prevents Voltage Changes Near the End of Action Potentials from Affecting Calcium Currents.

PubMed

Clarke, Stephen G; Scarnati, Matthew S; Paradiso, Kenneth G

2016-11-09

At chemical synapses, presynaptic action potentials (APs) activate voltage-gated calcium channels, allowing calcium to enter and trigger neurotransmitter release. The duration, peak amplitude, and shape of the AP falling phase alter calcium entry, which can affect neurotransmitter release significantly. In many neurons, APs do not immediately return to the resting potential, but instead exhibit a period of depolarization or hyperpolarization referred to as an afterpotential. We hypothesized that presynaptic afterpotentials should alter neurotransmitter release by affecting the electrical driving force for calcium entry and calcium channel gating. In support of this, presynaptic calcium entry is affected by afterpotentials after standard instant voltage jumps. Here, we used the mouse calyx of Held synapse, which allows simultaneous presynaptic and postsynaptic patch-clamp recording, to show that the postsynaptic response is affected significantly by presynaptic afterpotentials after voltage jumps. We therefore tested the effects of presynaptic afterpotentials using simultaneous presynaptic and postsynaptic recordings and AP waveforms or real APs. Surprisingly, presynaptic afterpotentials after AP stimuli did not alter calcium channel responses or neurotransmitter release appreciably. We show that the AP repolarization time course causes afterpotential-induced changes in calcium driving force and changes in calcium channel gating to effectively cancel each other out. This mechanism, in which electrical driving force is balanced by channel gating, prevents changes in calcium influx from occurring at the end of the AP and therefore acts to stabilize synaptic transmission. In addition, this mechanism can act to stabilize neurotransmitter release when the presynaptic resting potential changes. The shape of presynaptic action potentials (APs), particularly the falling phase, affects calcium entry and small changes in calcium influx can produce large changes in postsynaptic responses. We hypothesized that afterpotentials, which often follow APs, affect calcium entry and neurotransmitter release. We tested this in calyx of Held nerve terminals, which allow simultaneous recording of presynaptic calcium currents and postsynaptic responses. Surprisingly, presynaptic afterpotentials did not alter calcium current or neurotransmitter release. We show that the AP falling phase causes afterpotential-induced changes in electrical driving force and calcium channel gating to cancel each other out. This mechanism regulates calcium entry at the end of APs and therefore stabilizes synaptic transmission. This also stabilizes responses when the presynaptic resting potential changes. Copyright © 2016 the authors 0270-6474/16/3611559-14$15.00/0.

Calcium-dependent inactivation of calcium channels in cochlear hair cells of the chicken.

PubMed

Lee, Seunghwan; Briklin, Olga; Hiel, Hakim; Fuchs, Paul

2007-09-15

Voltage-gated calcium channels support both spontaneous and sound-evoked neurotransmitter release from ribbon synapses of cochlear hair cells. A variety of regulatory mechanisms must cooperate to ensure the appropriate level of activity in the restricted pool of synaptic calcium channels ( approximately 100) available to each synaptic ribbon. One potential feedback mechanism, calcium-dependent inactivation (CDI) of voltage-gated, L-type calcium channels, can be modulated by calmodulin-like calcium-binding proteins. CDI of voltage-gated calcium current was studied in hair cells of the chicken's basilar papilla (analogous to the mammalian cochlea) after blocking the predominant potassium conductances. For inactivating currents produced by 2.5 s steps to the peak of the current-voltage relation (1 mm EGTA internal calcium buffer), single exponential fits yielded an average decay time constant of 1.92 +/- 0.18 s (mean +/- s.e.m., n = 12) at 20-22 degrees C, while recovery occurred with a half-time of approximately 10 s. Inactivation produced no change in reversal potential, arguing that the observed relaxation did not result from alternative processes such as calcium accumulation or activation of residual potassium currents. Substitution of external calcium with barium greatly reduced inactivation, while inhibition of endoplasmic calcium pumps with t-benzohydroquinone (BHQ) or thapsigargin made inactivation occur faster and to a greater extent. Raising external calcium 10-fold (from 2 to 20 mm) increased peak current 3-fold, but did not alter the extent or time course of CDI. However, increasing levels of internal calcium buffer consistently reduced the rate and extent of inactivation. With 1 mm EGTA buffering and in 2 mm external calcium, the available pool of calcium channels was half-inactivated near the resting membrane potential (-50 mV). CDI may be further regulated by calmodulin-like calcium-binding proteins (CaBPs). mRNAs for several CaBPs are expressed in chicken cochlear tissue, and antibodies to CaBP4 label hair cells, but not supporting cells, equivalent to the pattern seen in mammalian cochlea. Thus, molecular mechanisms that underlie CDI appeared to be conserved across vertebrate species, may provide a means to adjust calcium channel open probability, and could serve to maintain the set-point for spontaneous release from the ribbon synapse.

Calcium-dependent inactivation of calcium channels in cochlear hair cells of the chicken

PubMed Central

Lee, Seunghwan; Briklin, Olga; Hiel, Hakim; Fuchs, Paul

2007-01-01

Voltage-gated calcium channels support both spontaneous and sound-evoked neurotransmitter release from ribbon synapses of cochlear hair cells. A variety of regulatory mechanisms must cooperate to ensure the appropriate level of activity in the restricted pool of synaptic calcium channels (∼100) available to each synaptic ribbon. One potential feedback mechanism, calcium-dependent inactivation (CDI) of voltage-gated, L-type calcium channels, can be modulated by calmodulin-like calcium-binding proteins. CDI of voltage-gated calcium current was studied in hair cells of the chicken's basilar papilla (analogous to the mammalian cochlea) after blocking the predominant potassium conductances. For inactivating currents produced by 2.5 s steps to the peak of the current–voltage relation (1 mm EGTA internal calcium buffer), single exponential fits yielded an average decay time constant of 1.92 ± 0.18 s (mean ±s.e.m., n = 12) at 20–22°C, while recovery occurred with a half-time of ∼10 s. Inactivation produced no change in reversal potential, arguing that the observed relaxation did not result from alternative processes such as calcium accumulation or activation of residual potassium currents. Substitution of external calcium with barium greatly reduced inactivation, while inhibition of endoplasmic calcium pumps with t-benzohydroquinone (BHQ) or thapsigargin made inactivation occur faster and to a greater extent. Raising external calcium 10-fold (from 2 to 20 mm) increased peak current 3-fold, but did not alter the extent or time course of CDI. However, increasing levels of internal calcium buffer consistently reduced the rate and extent of inactivation. With 1 mm EGTA buffering and in 2 mm external calcium, the available pool of calcium channels was half-inactivated near the resting membrane potential (−50 mV). CDI may be further regulated by calmodulin-like calcium-binding proteins (CaBPs). mRNAs for several CaBPs are expressed in chicken cochlear tissue, and antibodies to CaBP4 label hair cells, but not supporting cells, equivalent to the pattern seen in mammalian cochlea. Thus, molecular mechanisms that underlie CDI appeared to be conserved across vertebrate species, may provide a means to adjust calcium channel open probability, and could serve to maintain the set-point for spontaneous release from the ribbon synapse. PMID:17656437

Calcium absorption from fortified ice cream formulations compared with calcium absorption from milk.

PubMed

van der Hee, Regine M; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S M J E; Rietveld, Anton G; Wilkinson, Joy E; Quail, Patricia J; Berry, Mark J; Dainty, Jack R; Teucher, Birgit; Fairweather-Tait, Susan J

2009-05-01

Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Effects on calcium absorption were evaluated by analysis of variance. Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%+/-8%, 28%+/-5%, and 31%+/-9%, respectively, and did not differ significantly (P=0.159). Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium.

Impact of calcium signaling during infection of Neisseria meningitidis to human brain microvascular endothelial cells.

PubMed

Asmat, Tauseef M; Tenenbaum, Tobias; Jonsson, Ann-Beth; Schwerk, Christian; Schroten, Horst

2014-01-01

The pili and outer membrane proteins of Neisseria meningitidis (meningococci) facilitate bacterial adhesion and invasion into host cells. In this context expression of meningococcal PilC1 protein has been reported to play a crucial role. Intracellular calcium mobilization has been implicated as an important signaling event during internalization of several bacterial pathogens. Here we employed time lapse calcium-imaging and demonstrated that PilC1 of meningococci triggered a significant increase in cytoplasmic calcium in human brain microvascular endothelial cells, whereas PilC1-deficient meningococci could not initiate this signaling process. The increase in cytosolic calcium in response to PilC1-expressing meningococci was due to efflux of calcium from host intracellular stores as demonstrated by using 2-APB, which inhibits the release of calcium from the endoplasmic reticulum. Moreover, pre-treatment of host cells with U73122 (phospholipase C inhibitor) abolished the cytosolic calcium increase caused by PilC1-expressing meningococci demonstrating that active phospholipase C (PLC) is required to induce calcium transients in host cells. Furthermore, the role of cytosolic calcium on meningococcal adherence and internalization was documented by gentamicin protection assay and double immunofluorescence (DIF) staining. Results indicated that chelation of intracellular calcium by using BAPTA-AM significantly impaired PilC1-mediated meningococcal adherence to and invasion into host endothelial cells. However, buffering of extracellular calcium by BAPTA or EGTA demonstrated no significant effect on meningococcal adherence to and invasion into host cells. Taken together, these results indicate that meningococci induce calcium release from intracellular stores of host endothelial cells via PilC1 and cytoplasmic calcium concentrations play a critical role during PilC1 mediated meningococcal adherence to and subsequent invasion into host endothelial cells.

Calcium responses to synaptically activated bursts of action potentials and their synapse-independent replay in cultured networks of hippocampal neurons.

PubMed

Bengtson, C Peter; Kaiser, Martin; Obermayer, Joshua; Bading, Hilmar

2013-07-01

Both synaptic N-methyl-d-aspartate (NMDA) receptors and voltage-operated calcium channels (VOCCs) have been shown to be critical for nuclear calcium signals associated with transcriptional responses to bursts of synaptic input. However the direct contribution to nuclear calcium signals from calcium influx through NMDA receptors and VOCCs has been obscured by their concurrent roles in action potential generation and synaptic transmission. Here we compare calcium responses to synaptically induced bursts of action potentials with identical bursts devoid of any synaptic contribution generated using the pre-recorded burst as the voltage clamp command input to replay the burst in the presence of blockers of action potentials or ionotropic glutamate receptors. Synapse independent replays of bursts produced nuclear calcium responses with amplitudes around 70% of their original synaptically generated signals and were abolished by the L-type VOCC blocker, verapamil. These results identify a major direct source of nuclear calcium from local L-type VOCCs whose activation is boosted by NMDA receptor dependent depolarization. The residual component of synaptically induced nuclear calcium signals which was both VOCC independent and NMDA receptor dependent showed delayed kinetics consistent with a more distal source such as synaptic NMDA receptors or internal stores. The dual requirement of NMDA receptors and L-type VOCCs for synaptic activity-induced nuclear calcium dependent transcriptional responses most likely reflects a direct somatic calcium influx from VOCCs whose activation is amplified by synaptic NMDA receptor-mediated depolarization and whose calcium signal is boosted by a delayed input from distal calcium sources mostly likely entry through NMDA receptors and release from internal stores. This article is part of a Special Issue entitled: 12th European Symposium on Calcium. Copyright © 2013 Elsevier B.V. All rights reserved.

Molecular Dynamics Simulations of Membrane-Bound STIM1 to Investigate Conformational Changes during STIM1 Activation upon Calcium Release.

PubMed

Mukherjee, Sreya; Karolak, Aleksandra; Debant, Marjolaine; Buscaglia, Paul; Renaudineau, Yves; Mignen, Olivier; Guida, Wayne C; Brooks, Wesley H

2017-02-27

Calcium is involved in important intracellular processes, such as intracellular signaling from cell membrane receptors to the nucleus. Typically, calcium levels are kept at less than 100 nM in the nucleus and cytosol, but some calcium is stored in the endoplasmic reticulum (ER) lumen for rapid release to activate intracellular calcium-dependent functions. Stromal interacting molecule 1 (STIM1) plays a critical role in early sensing of changes in the ER's calcium level, especially when there is a sudden release of stored calcium from the ER. Inactive STIM1, which has a bound calcium ion, is activated upon ion release. Following activation of STIM1, there is STIM1-assisted initiation of extracellular calcium entry through channels in the cell membrane. This extracellular calcium entering the cell then amplifies intracellular calcium-dependent actions. At the end of the process, ER levels of stored calcium are reestablished. The main focus of this work was to study the conformational changes accompanying homo- or heterodimerization of STIM1. For this purpose, the ER luminal portion of STIM1 (residues 58-236), which includes the sterile alpha motif (SAM) domain plus the calcium-binding EF-hand domains 1 and 2 attached to the STIM1 transmembrane region (TM), was modeled and embedded in a virtual membrane. Next, molecular dynamics simulations were performed to study the conformational changes that take place during STIM1 activation and subsequent protein-protein interactions. Indeed, the simulations revealed exposure of residues in the EF-hand domains, which may be important for dimerization steps. Altogether, understanding conformational changes in STIM1 can help in drug discovery when targeting this key protein in intracellular calcium functions.

Calcium carbonate nucleation in an alkaline lake surface water, Pyramid Lake, Nevada, USA

USGS Publications Warehouse

Reddy, Michael M.; Hoch, Anthony

2012-01-01

Calcium concentration and calcite supersaturation (Ω) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has Ω values of 10-16. Notwithstanding high Ω, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean Ω at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water Ω. Calcium concentration and Ω regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower Ω than filtered samples. Calcium concentration and Ω at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (Ω) + B. The best fit rate equation "Rate (Δ mM/Δ min) = -0.0026 Ω + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, Ω at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors.

Calcium Carbonate Nucleation in an Alkaline Lake Surface Water, Pyramid Lake, Nevada, USA

USGS Publications Warehouse

Reddy, M.M.; Hoch, A.

2012-01-01

Calcium concentration and calcite supersaturation (??) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has ?? values of 10-16. Notwithstanding high ??, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean ?? at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water ??. Calcium concentration and ?? regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower ?? than filtered samples. Calcium concentration and ?? at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (??) + B. The best fit rate equation "Rate (?? mM/?? min) = -0.0026 ?? + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, ?? at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors. ?? 2011 U.S. Government.

Calcium balance in young adults on a vegan and lactovegetarian diet.

PubMed

Kohlenberg-Mueller, Kathrin; Raschka, Ladislav

2003-01-01

For people in Western countries, the vegan diet has the advantage of low energy intake, but the calcium status of this strictly plant-based diet is still unclear. The aim of this study was to determine the calcium balance of individuals on a vegan diet in comparison with a lactovegetarian diet in a short-term investigation. Seven women and one man, ranging in age from 19 to 24 years, received during the first 10 days a vegan diet based on plant foods and calcium-rich mineral water and a lactovegetarian diet during the following 10 days. Portion size was adapted to the subjects' individual energy requirements. Calcium status was assessed by means of calcium intake in food and calcium output in feces and urine as measured by flame atomic absorption spectrophotometry. In addition, deoxypyridinoline was measured in urine as a marker of bone resorption. The results show a significantly smaller daily calcium intake with an average of 843 +/- 140 mg in the vegan versus 1322 +/- 303 mg in the lactovegetarian diet. Apparent calcium absorption rates were calculated as 26% +/- 15% in the vegan and 24% +/- 8% in the lactovegetarian group (NS). The calcium balance was positive both in the vegan diet (119 +/- 113 mg/day) and in the lactovegetarian diet (211 +/- 136 mg/day) (NS). Deoxypyridinoline excretion showed no significant difference between the two diets (105 +/- 31 and 98 +/- 23 nmol/day). The present results indicate that calcium balance and a marker of bone turnover are not affected significantly when calcium is provided either solely by plant foods or by a diet including dairy products, despite the significantly different calcium intake levels in the diets. We conclude that a well-selected vegan diet maintains calcium status, at least for a short-term period.

Determination of (210)Po in calcium supplements and the possible related dose assessment to the consumers.

PubMed

Strumińska-Parulska, Dagmara I

2015-12-01

The aim of this pioneer study was to investigate the most popular calcium supplements as a potential additional source of polonium (210)Po in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The objectives of this research were to investigate the naturally occurring (210)Po activity concentrations in calcium supplements, find the correlations between (210)Po concentration in medicament and calcium chemical form, and calculate the effective radiation dose connected to analyzed calcium supplement consumption. As results showed, (210)Po concentrations in natural origin calcium supplements (especially sedimentary rocks) were higher than the other analyzed. Also the results of (210)Po analysis obtained for inorganic forms of calcium supplements were higher. The highest (210)Po activity concentrations were determined in mineral tablets made from sedimentary rocks: dolomite and chalk - 3.88 ± 0.22 and 3.36 ± 0.10 mBq g(-1) respectively; while the lowest in organic calcium compounds: calcium lactate and calcium gluconate - 0.07 ± 0.02 and 0.17 ± 0.01 mBq g(-1). The annual effective radiation doses from supplements intake were estimated as well. The highest annual radiation dose from (210)Po taken with 1 tablet of calcium supplement per day was connected to sample made from chalk - 2.5 ± 0.07 μSv year(-1), while the highest annual radiation dose from (210)Po taken with 1 g of pure calcium per day was connected to dolomite - 12.7 ± 0.70 μSv year(-1). Copyright © 2015 Elsevier Ltd. All rights reserved.

Serum 1,25-dihydroxyvitamin D and calcium intake affect rates of bone calcium deposition during pregnancy and the early postpartum period123

PubMed Central

O'Brien, Kimberly O; Donangelo, Carmen M; Ritchie, Lorrene D; Gildengorin, Ginny; Abrams, Steve

2012-01-01

Background: Factors affecting bone calcium deposition across pregnancy and lactation are not well characterized. Objective: The impact of maternal age, calcium intake, race-ethnicity, and vitamin D status on the rate of bone calcium deposition (VO+) was assessed across pregnancy and lactation. Design: Stable calcium isotopes were given to 46 women at pre- or early pregnancy (trimester 1), late pregnancy (trimester 3), and 3–10 wk postpartum. Three cohorts were included: 23 adolescents from Baltimore (MD), aged 16.5 ± 1.4 y (mean ± SD; Baltimore cohort); 13 adults from California, aged 29.5 ± 2.6 y (California cohort); and 10 adults from Brazil, aged 30.4 ± 4.0 y (Brazil cohort). The total exchangeable calcium pool, VO+, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25(OH)2D], parathyroid hormone, and calcium intake were evaluated. Results: At trimester 3, inverse associations between 1,25(OH)2D and VO+ were evident in the Baltimore (P = 0.059) and Brazil (P = 0.008) cohorts and in the whole group (P = 0.029); calcium intake was not a significant determinant of VO+ in any group during pregnancy. At postpartum, a significant positive association was evident between VO+ and calcium intake (P ≤ 0.002) and between VO+ and African ethnicity (P ≤ 0.004) in the whole group and within the Baltimore and Brazil cohorts. Conclusions: Elevated 1,25(OH)2D was associated with decreased rates of bone calcium deposition during late pregnancy, a finding that was particularly evident in pregnant adolescents and adult women with low calcium intakes. Higher dietary calcium intakes and African ethnicity were associated with elevated rates of bone calcium deposition in the postpartum period. PMID:22648718

Calcium Intake, Major Dietary Sources and Bone Health Indicators in Iranian Primary School Children

PubMed Central

Omidvar, Nasrin; Neyestani, Tirang-Reza; Hajifaraji, Majid; Eshraghian, Mohammad-Reza; Rezazadeh, Arezoo; Armin, Saloumeh; Haidari, Homa; Zowghi, Telma

2015-01-01

Background: Adequate calcium intake may have a crucial role with regards to prevention of many chronic diseases, including hypertension, hypercholesterolemia, different types of cancer, obesity and osteoporosis. In children, sufficient calcium intake is especially important to support the accelerated growth spurt during the preteen and teenage years and to increase bone mineral mass to lay the foundation for older age. Objectives: This study aimed to assess daily calcium intake in school-age children to ensure whether they fulfill the FGP dairy serving recommendations, the recommended levels of daily calcium intake and to assess the relationship between dietary calcium intake and major bone health indicators. Patients and Methods: A total of 501 Iranian school-age children were randomly selected. Calcium intake was assessed using a semi-quantitative food frequency questionnaire. Bone health indicators were also assessed. Results: Dairy products contributed to 69.3% of the total calcium intake of the children. Daily adequate intake of calcium was achieved by 17.8% of children. Only 29.8% met the Food guide pyramid recommendations for dairy intake. Dietary calcium intake was not significantly correlated with serum calcium and other selected biochemical indicators of bone health. Conclusions: The need for planning appropriate nutrition strategies for overcoming inadequate calcium intake in school age children in the city of Tehran is inevitable. PMID:26199684

Dietary coral calcium and zeolite protects bone in a mouse model for postmenopausal bone loss.

PubMed

Banu, Jameela; Varela, Erika; Guerra, Juan M; Halade, Ganesh; Williams, Paul J; Bahadur, Ali N; Hanaoka, Kokichi; Fernandes, Gabriel

2012-12-01

In patients diagnosed with osteoporosis, calcium is lost from bones making them weaker and easily susceptible to fractures. Supplementation of calcium is highly recommended for such conditions. However, the source of calcium plays an important role in the amount of calcium that is assimilated into bone. We hypothesize that naturally occurring coral calcium and zeolite may prevent ovariectomy-induced bone loss. We have measured bone loss in ovariectomized mice supplemented with coral calcium and Zeolite. Female C57BL/6 mice were either sham-operated or ovariectomized and fed diets containing coral calcium or zeolite for 6 months. Serum was analyzed for bone biochemical markers and cytokines. Bones were analyzed using dual x-ray absorbtiometry, peripheral quantitative computed tomography, and micro-computed tomography densitometry. In the distal femoral metaphysis, total bone and cortical bone mass was restored and the endocortical surface was significantly decreased in coral calcium and zeolite fed ovariectomized (OVX) mice. Trabecular number and the ratio of bone volume to total volume was higher in OVX mice after coral calcium and zeolite feeding, while trabecular separation decreased in the different treatment OVX groups. Coral calcium protected bone to a lesser extent in the proximal tibia and lumbar vertebrae. Overall, coral calcium and zeolite may protect postmenopausal bone loss. Copyright © 2012 Elsevier Inc. All rights reserved.

Biological and medical significance of calcium phosphates.

PubMed

Dorozhkin, Sergey V; Epple, Matthias

2002-09-02

The inorganic part of hard tissues (bones and teeth) of mammals consists of calcium phosphate, mainly of apatitic structure. Similarly, most undesired calcifications (i.e. those appearing as a result of various diseases) of mammals also contain calcium phosphate. For example, atherosclerosis results in blood-vessel blockage caused by a solid composite of cholesterol with calcium phosphate. Dental caries result in a replacement of less soluble and hard apatite by more soluble and softer calcium hydrogenphosphates. Osteoporosis is a demineralization of bone. Therefore, from a chemical point of view, processes of normal (bone and teeth formation and growth) and pathological (atherosclerosis and dental calculus) calcifications are just an in vivo crystallization of calcium phosphate. Similarly, dental caries and osteoporosis can be considered to be in vivo dissolution of calcium phosphates. On the other hand, because of the chemical similarity with biological calcified tissues, all calcium phosphates are remarkably biocompatible. This property is widely used in medicine for biomaterials that are either entirely made of or coated with calcium phosphate. For example, self-setting bone cements made of calcium phosphates are helpful in bone repair and titanium substitutes covered with a surface layer of calcium phosphates are used for hip-joint endoprostheses and tooth substitutes, to facilitate the growth of bone and thereby raise the mechanical stability. Calcium phosphates have a great biological and medical significance and in this review we give an overview of the current knowledge in this subject.

Calcium and vitamin D intake and biochemical tests in short-stature children and adolescents.

PubMed

Bueno, A L; Czepielewski, M A; Raimundo, F V

2010-11-01

Growth is highly dependent on the absorption of nutrients. Inadequate calcium and vitamin D intake may compromise bone mineralization and growth. There is a great deal of concern regarding calcium and vitamin D intake, as well as biochemical changes in children and adolescents, which led us to investigate calcium and vitamin D levels during growth. Fifty-eight children and adolescents with short stature (z-score <3 s.d.) were evaluated from September 2005 to February 2007. Blood biochemical analyses and 24-h urine tests were performed and were used to evaluate calcium, phosphorus, creatinine, sodium, alkaline phosphatase, parathyroid hormone (PTH) and 25(OH)D levels. Dietary inquiries, repeated three times, were used to estimate the actual intake of these substances. A reduced calcium (608.6 mg/day) and vitamin D (72.5 IU/day) intake was observed. Calcium excretion in 24-h urine (56 mg/24 h) and calcium excretion by weight (2.0 mg/24 h/kg) showed scores that were below normal. A negative correlation between PTH and both dietary vitamin D (r=-0.46; P<0.01) and calcium intake (r =-0.41; P<0.001) was observed. The low calcium and vitamin D intake observed in short-stature children and adolescents was associated with biochemical results, and suggested that PTH and calcium excretion may be useful screening tests for evaluating dietary calcium and vitamin D.

Calcium

MedlinePlus

... You'll also find calcium in broccoli and dark green, leafy vegetables (especially collard and turnip greens, ... can enjoy good sources of calcium such as dark green, leafy vegetables, broccoli, chickpeas, and calcium-fortified ...

Influence of calcium oxalate crystal accumulation on the calcium content of seeds from Medicago truncatula

USDA-ARS?s Scientific Manuscript database

Crystals of calcium oxalate often form in cells adjacent to the vascular bundles in the tissues along the xylem stream. This spatial crystal pattern suggests a role for calcium oxalate formation in regulating calcium transport and partitioning to edible organs such as seeds. To investigate this pote...

75 FR 51002 - Pure Magnesium In Granular Form from the People's Republic of China: Initiation of Changed...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-18

.... SUPPLEMENTARY INFORMATION: Background On November 19, 2001, the Department published in the Federal Register an... are: lime, calcium metal, calcium silicon, calcium carbide, calcium carbonate, carbon, slag coagulants, fluorspar, nephaline syenite, feldspar, aluminum, alumina (Al2O3), calcium aluminate, soda ash, hydrocarbons...

21 CFR 184.1187 - Calcium alginate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae...

21 CFR 184.1187 - Calcium alginate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae...

21 CFR 184.1201 - Calcium glycerophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium glycerophosphate. 184.1201 Section 184... as GRAS § 184.1201 Calcium glycerophosphate. (a) Calcium glycerophosphate (C3H7CaO6P, CAS Reg. No... mixture of calcium β-, and D-, and L-α-glycerophosphate. (b) The ingredient meets the specifications of...

Biophysical characterization of the calmodulin-like domain of Plasmodium falciparum calcium dependent protein kinase 3

PubMed Central

Andresen, Cecilia; Niklasson, Markus; Cassman Eklöf, Sofie; Wallner, Björn

2017-01-01

Calcium dependent protein kinases are unique to plants and certain parasites and comprise an N-terminal segment and a kinase domain that is regulated by a C-terminal calcium binding domain. Since the proteins are not found in man they are potential drug targets. We have characterized the calcium binding lobes of the regulatory domain of calcium dependent protein kinase 3 from the malaria parasite Plasmodium falciparum. Despite being structurally similar, the two lobes differ in several other regards. While the monomeric N-terminal lobe changes its structure in response to calcium binding and shows global dynamics on the sub-millisecond time-scale both in its apo and calcium bound states, the C-terminal lobe could not be prepared calcium-free and forms dimers in solution. If our results can be generalized to the full-length protein, they suggest that the C-terminal lobe is calcium bound even at basal levels and that activation is caused by the structural reorganization associated with binding of a single calcium ion to the N-terminal lobe. PMID:28746405

Proteomic analysis of a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate: a case report.

PubMed

Kaneko, Kiyoko; Matsuta, Yosuke; Moriyama, Manabu; Yasuda, Makoto; Chishima, Noriharu; Yamaoka, Noriko; Fukuuchi, Tomoko; Miyazawa, Katsuhito; Suzuki, Koji

2014-03-01

The objective of the present study was to investigate the matrix protein of a rare urinary stone that contained calcium carbonate. A urinary stone was extracted from a 34-year-old male patient with metabolic alkalosis. After X-ray diffractometry and infrared analysis of the stone, proteomic analysis was carried out. The resulting mass spectra were evaluated with protein search software, and matrix proteins were identified. X-ray diffraction and infrared analysis confirmed that the stone contained calcium carbonate and calcium oxalate dihydrate. Of the identified 53 proteins, 24 have not been previously reported from calcium oxalate- or calcium phosphate-containing stones. The protease inhibitors and several proteins related to cell adhesion or the cytoskeleton were identified for the first time. We analyzed in detail a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate. Considering the formation of a calcium carbonate stone, the new identified proteins should play an important role on the urolithiasis process in alkaline condition. © 2013 The Japanese Urological Association.

Novel Peptide with Specific Calcium-Binding Capacity from Schizochytrium sp. Protein Hydrolysates and Calcium Bioavailability in Caco-2 Cells

PubMed Central

Cai, Xixi; Lin, Jiaping; Wang, Shaoyun

2016-01-01

Peptide-calcium can probably be a suitable supplement to improve calcium absorption in the human body. In this study, a specific peptide Phe-Tyr (FY) with calcium-binding capacity was purified from Schizochytrium sp. protein hydrolysates through gel filtration chromatography and reversed phase HPLC. The calcium-binding capacity of FY reached 128.77 ± 2.57 μg/mg. Results of ultraviolet spectroscopy, fluorescence spectroscopy, and infrared spectroscopy showed that carboxyl groups, amino groups, and amido groups were the major chelating sites. FY-Ca exhibited excellent thermal stability and solubility, which were beneficial to be absorbed and transported in the basic intestinal tract of the human body. Moreover, the calcium bioavailability in Caco-2 cells showed that FY-Ca could enhance calcium uptake efficiency by more than three times when compared with CaCl2, and protect calcium ions against dietary inhibitors, such as tannic acid, oxalate, phytate, and Zn2+. Our findings further the progress of algae-based peptide-calcium, suggesting that FY-Ca has the potential to be developed as functionally nutraceutical additives. PMID:28036002

Magnesium-to-calcium ratio in tap water, and its relationship to geological features and the incidence of calcium-containing urinary stones.

PubMed

Kohri, K; Kodama, M; Ishikawa, Y; Katayama, Y; Takada, M; Katoh, Y; Kataoka, K; Iguchi, M; Kurita, T

1989-11-01

We examined the relationship among magnesium and calcium content in tap water, the geological features and urinary stone incidence in Japan. The magnesium-to-calcium ratio in tap water correlated negatively with the incidence of urolithiasis. There was no correlation between calcium and magnesium concentration in tap water and urinary stone incidence. Geological features in Japan were classified into 5 groups. The magnesium-to-calcium ratio in the basalt areas was higher than in the other areas, while ratio in the granite areas was low. In the sedimentary rock areas calcium and magnesium concentrations were high; the magnesium-to-calcium ratio in these areas was between those of the basalt and granite areas. The limestone areas had a much higher calcium concentration. The incidence of urinary stones in the sedimentary rock and basalt areas was lower than that of the granite areas, while that in the limestone areas was the highest. Thus, the incidence of urinary stone is related to the magnesium-to-calcium ratio in tap water and the geological area.

A novel hydrolytic product from flesh of Mactra veneriformis and its bioactivities in calcium supplement

NASA Astrophysics Data System (ADS)

Wang, Lingchong; Chen, Shiyong; Liu, Rui; Wu, Hao

2012-09-01

To prepare calcium-binding peptides, the flesh residue of Mactra Veneriformis was subjected to enzymatic hydrolysis. By comparing the capability of combining calcium of the hydrolyzates, pepsin was confirmed to be the most suitable enzyme for hydrolyzing the flesh residue to release calcium-binding peptides among the seven tested proteases. The pepsin hydrolyzate (PHM) was divided into three fractions according to the molecule weight of its composition, which ranged from 0.5 to 15 kDa. The low-molecule-weight fraction named PHM-3 had the highest capability in combining calcium. The peptides existing in the PHM-3 fraction consisted of higher contents of Glu, Ala and Leu, and could produce one type of calcium-peptide complex by powerfully chelating calcium ions. PHM-3 products could effectively increase calcium absorption and retention while they decreased the calcium excretion in animal tests. Additionally, symptoms caused by low calcium bioavailability in ovariectomized rats, such as bone mineral density reduction and mechanical strength loss could be significantly ameliorated by the hydrolytic products addition in diet.

Model of Inclusion Evolution During Calcium Treatment in the Ladle Furnace

NASA Astrophysics Data System (ADS)

Tabatabaei, Yousef; Coley, Kenneth S.; Irons, Gordon A.; Sun, Stanley

2018-04-01

Calcium treatment of steel is typically employed to modify alumina inclusions to liquid calcium aluminates. However, injected calcium also reacts with the dissolved sulfur to form calcium sulfide. The current work aims to develop a kinetic model for the evolution of oxide and sulfide inclusions in Al-killed alloyed steel during Ca treatment in the ladle refining process. The model considers dissolution of the calcium from the calcium bubbles into the steel and reduction of calcium oxide in the slag to dissolved calcium. A steel-inclusion kinetic model is used for mass transfer to the inclusion interface and diffusion within the calcium aluminate phases formed on the inclusion. The inclusion-steel kinetic model is then coupled with a previously developed steel-slag kinetic model. The coupled inclusion-steel-slag kinetic model is applied to the chemical composition changes in molten steel, slag, and evolution of inclusions in the ladle. The result of calculations is found to agree well with an industrial heat for species in the steel as well as inclusions during Ca treatment.

Calsequestrin mediates changes in spontaneous calcium release profiles.

PubMed

Tania, Nessy; Keener, James P

2010-08-07

Calsequestrin (CSQ) is the primary calcium buffer within the sarcoplasmic reticulum (SR) of cardiac cells. It has also been identified as a regulator of Ryanodine receptor (RyR) calcium release channels by serving as a SR luminal sensor. When calsequestrin is free and unbound to calcium, it can bind to RyR and desensitize the channel from cytoplasmic calcium activation. In this paper, we study the role of CSQ as a buffer and RyR luminal sensor using a mechanistic model of RyR-CSQ interaction. By using various asymptotic approximations and mean first exit time calculation, we derive a minimal model of a calcium release unit which includes CSQ dependence. Using this model, we then analyze the effect of changing CSQ expression on the calcium release profile and the rate of spontaneous calcium release. We show that because of its buffering capability, increasing CSQ increases the spark duration and size. However, because of luminal sensing effects, increasing CSQ depresses the basal spark rate and increases the critical SR level for calcium release termination. Finally, we show that with increased bulk cytoplasmic calcium concentration, the CRU model exhibits deterministic oscillations.

Calcium signaling in neuronal cells exposed to the munitions compound Cyclotrimethylenetrinitramine (RDX).

PubMed

Ehrich, Marion; Wu, Xiaohua; Werre, Stephen R; Major, Michael A; McCain, Wilfred C; Reddy, Gunda

2009-01-01

Cyclotrimethylenetrinitramine (RDX) has been used extensively as an explosive in military munitions. Mechanisms for seizure production, seen in past animal studies, have not been described. Increased calcium levels contribute to excitotoxicity, so in this study neuroblastoma cells are loaded with calcium-indicating dye before application of 1.5 microM to 7.5 mM RDX, with fluorescence recorded for 30 cycles of 11 seconds each. The lowest concentration of RDX increases calcium fluorescence significantly above baseline for cycles 2 to 8; millimolar concentrations increase calcium fluorescence significantly above baseline for cycles 2 to 30. Increases in calcium, like those of 200 nM carbachol, are prevented with 10 mM of calcium chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N,N tetra-acetic acid (EGTA, tetrasodium salt). Calcium channel blocker verapamil (20 microM), Ca(2+)-ATPase inhibitor thapsigargin (5 microM), and general membrane stabilizer lidocaine (10 mM) partially attenuate carbachol- and RDX-induced increases in calcium, suggesting that RDX transiently increases intracellular calcium by multiple mechanisms.

Calcium influx is required for endocytotic membrane retrieval

PubMed Central

Vogel, Steven S.; Smith, Robert M.; Baibakov, Boris; Ikebuchi, Yoshihide; Lambert, Nevin A.

1999-01-01

Cells use endocytotic membrane retrieval to compensate for excess surface membrane after exocytosis. Retrieval is thought to be calcium-dependent, but the source of this calcium is not known. We found that, in sea urchin eggs, endocytotic membrane retrieval required extracellular calcium. Inhibitors of P-type calcium channels—cadmium, ω-conotoxin MVIIC, ω-agatoxin IVA, and ω-agatoxin TK—blocked membrane retrieval; selective inhibitors of N-type and L-type channels did not. Treatment with calcium ionophores overcame agatoxin inhibition in a calcium-dependent manner. Cadmium blocked membrane retrieval when applied during the first 5 minutes after fertilization, the period when the membrane potential is depolarized. We conclude that calcium influx through ω-agatoxin-sensitive channels plays a key role in signaling for endocytotic membrane retrieval. PMID:10220411

TRIENNIAL LACTATION SYMPOSIUM/BOLFA: Serotonin and the regulation of calcium transport in dairy cows.

PubMed

Hernandez, L L

2017-12-01

The mammary gland regulates maternal metabolism during lactation. Numerous factors within the tissue send signals to shift nutrients to the mammary gland for milk synthesis. Serotonin is a monoamine that has been well documented to regulate several aspects of lactation among species. Maintenance of maternal calcium homeostasis during lactation is a highly evolved process that is elegantly regulated by the interaction of the mammary gland with the bone, gut, and kidney tissues. It is well documented that dietary calcium is insufficient to maintain maternal calcium concentrations during lactation, and mammals must rely on bone resorption to maintain normocalcemia. Our recent work focused on the ability of the mammary gland to function as an accessory parathyroid gland during lactation. It was demonstrated that serotonin acts to stimulate parathyroid hormone-related protein (PTHrP) in the mammary gland during lactation. The main role of mammary-derived PTHrP during mammalian lactation is to stimulate bone resorption to maintain maternal calcium homeostasis during lactation. In addition to regulating PTHrP, it was shown that serotonin appears to directly affect calcium transporters and pumps in the mammary gland. Our current working hypothesis regarding the control of calcium during lactation is as follows: serotonin directly stimulates PTHrP production in the mammary gland through interaction with the sonic hedgehog signaling pathway. Simultaneously, serotonin directly increases calcium movement into the mammary gland and, subsequently, milk. These 2 direct actions of serotonin combine to induce a transient maternal hypocalcemia required to further stimulate PTHrP production and calcium mobilization from bone. Through these 2 routes, serotonin is able to improve maternal calcium concentrations. Furthermore, we have shown that Holstein and Jersey cows appear to regulate calcium in different manners and also respond differently to serotonergic stimulation of the calcium pathway. Our data in rodents and cows indicate that serotonin and calcium are working through a unique feedback loop with PTHrP during lactation to regulate milk calcium and maternal calcium homeostasis.

Calcium sensitivity of dicarboxylate transport in cultured proximal tubule cells

PubMed Central

Schiro, Faith R.; Pajor, Ana M.; Hamm, L. Lee

2011-01-01

Urinary citrate is an important inhibitor of calcium nephrolithiasis and is primarily determined by proximal tubule reabsorption. The major transporter to reabsorb citrate is Na+-dicarboxylate cotransporter (NaDC1), which transports dicarboxylates, including the divalent form of citrate. We previously found that opossum kidney (OK) proximal tubule cells variably express either divalent or trivalent citrate transport, depending on extracellular calcium. The present studies were performed to delineate the mechanism of the effect of calcium on citrate and succinate transport in these cells. Transport was measured using isotope uptake assays. In some studies, NaDC1 transport was studied in Xenopus oocytes, expressing either the rabbit or opossum ortholog. In the OK cell culture model, lowering extracellular calcium increased both citrate and succinate transport by more than twofold; the effect was specific in that glucose transport was not altered. Citrate and succinate were found to reciprocally inhibit transport at low extracellular calcium (<60 μM), but not at normal calcium (1.2 mM); this mutual inhibition is consistent with dicarboxylate transport. The inhibition varied progressively at intermediate levels of extracellular calcium. In addition to changing the relative magnitude and interaction of citrate and succinate transport, decreasing calcium also increased the affinity of the transport process for various other dicarboxylates. Also, the affinity for succinate, at low concentrations of substrate, was increased by calcium removal. In contrast, in oocytes expressing NaDC1, calcium did not have a similar effect on transport, indicating that NaDC1 could not likely account for the findings in OK cells. In summary, extracellular calcium regulates constitutive citrate and succinate transport in OK proximal tubule cells, probably via a novel transport process that is not NaDC1. The calcium effect on citrate transport parallels in vivo studies that demonstrate the regulation of urinary citrate excretion with urinary calcium excretion, a process that may be important in decreasing urinary calcium stone formation. PMID:21123491

Fruit Calcium: Transport and Physiology

PubMed Central

Hocking, Bradleigh; Tyerman, Stephen D.; Burton, Rachel A.; Gilliham, Matthew

2016-01-01

Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact the development, physical traits and disease susceptibility of fruit through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g., blossom end rot in tomatoes or bitter pit in apples). This review works toward an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved knowledge of the calcium-regulated signaling pathways that control ripening would assist in addressing calcium deficiency disorders and improving fruit pathogen resistance. PMID:27200042

Transcriptome Wide Identification and Validation of Calcium Sensor Gene Family in the Developing Spikes of Finger Millet Genotypes for Elucidating Its Role in Grain Calcium Accumulation

PubMed Central

Singh, Uma M.; Chandra, Muktesh; Shankhdhar, Shailesh C.; Kumar, Anil

2014-01-01

Background In finger millet, calcium is one of the important and abundant mineral elements. The molecular mechanisms involved in calcium accumulation in plants remains poorly understood. Transcriptome sequencing of genetically diverse genotypes of finger millet differing in grain calcium content will help in understanding the trait. Principal Finding In this study, the transcriptome sequencing of spike tissues of two genotypes of finger millet differing in their grain calcium content, were performed for the first time. Out of 109,218 contigs, 78 contigs in case of GP-1 (Low Ca genotype) and out of 120,130 contigs 76 contigs in case of GP-45 (High Ca genotype), were identified as calcium sensor genes. Through in silico analysis all 82 unique calcium sensor genes were classified into eight calcium sensor gene family viz., CaM & CaMLs, CBLs, CIPKs, CRKs, PEPRKs, CDPKs, CaMKs and CCaMK. Out of 82 genes, 12 were found diverse from the rice orthologs. The differential expression analysis on the basis of FPKM value resulted in 24 genes highly expressed in GP-45 and 11 genes highly expressed in GP-1. Ten of the 35 differentially expressed genes could be assigned to three documented pathways involved mainly in stress responses. Furthermore, validation of selected calcium sensor responder genes was also performed by qPCR, in developing spikes of both genotypes grown on different concentration of exogenous calcium. Conclusion Through de novo transcriptome data assembly and analysis, we reported the comprehensive identification and functional characterization of calcium sensor gene family. The calcium sensor gene family identified and characterized in this study will facilitate in understanding the molecular basis of calcium accumulation and development of calcium biofortified crops. Moreover, this study also supported that identification and characterization of gene family through Illumina paired-end sequencing is a potential tool for generating the genomic information of gene family in non-model species. PMID:25157851

Effects of calcium-fortified ice cream on markers of bone health.

PubMed

Ferrar, L; van der Hee, R M; Berry, M; Watson, C; Miret, S; Wilkinson, J; Bradburn, M; Eastell, R

2011-10-01

Premenopausal women with low calcium intakes consumed calcium-fortified ice cream daily for 28 days. Bone markers, NTX, CTX and PTH decreased significantly by 7 days, with some evidence of a calcium dose-dependent effect. Bone marker responses were observed within 1 h of consuming ice cream. Body weight remained constant over 28 days. Dietary calcium is important for lifelong bone health. Milk is a good source of bioavailable calcium, but consumption has declined among young adults. The aims were to determine whether calcium-fortified ice cream, a palatable source of calcium, produces significant, sustainable changes in bone turnover markers and parathyroid hormone (PTH) in premenopausal women with calcium intake below recommended UK levels. Eighty women, ages 20-39 years (calcium intake <750 mg/day) were randomised to consume lower saturated fat/sugar ice cream containing 96, 244, 459 or 676 mg calcium daily for 28 days. Urinary NTX/Cr, serum CTX, PINP, 1,25D and PTH were measured (baseline, days 1, 7 and 28). Acute changes in CTX and PTH were measured over 5 h (n = 29 women). There were significant mean decreases by 7 days in NTX/Cr, CTX, PTH and 1,25D and increases in PINP (one sample t tests), with a significant dose-dependent effect on CTX analysis of covariance. Only CTX remained suppressed at 28 days. Serum CTX and PTH decreased within 1 h. Body weight did not change significantly between baseline and 28 days. Daily consumption of calcium-fortified ice cream by premenopausal women may significantly reduce levels of the bone resorption marker serum CTX, without stimulating weight gain. The ice cream could be incorporated into the diet to replace low-calcium snacks and thus help individuals with habitually low calcium intakes to meet recommended intakes. The 244 mg calcium preparation would provide more than a quarter of the UK daily recommended nutrient intake for premenopausal women.

Calcium acetate or calcium carbonate for hyperphosphatemia of hemodialysis patients: a meta-analysis.

PubMed

Wang, Yong; Xie, Guoqiang; Huang, Yuanhang; Zhang, Han; Yang, Bo; Mao, Zhiguo

2015-01-01

High levels of serum phosphorus both at baseline and during follow-up are associated with increased mortality in dialysis patients, and administration of phosphate binders was independently associated with improved survival among hemodialysis population. Calcium-based phosphate binders are the most commonly used phosphate binders in developing countries for their relatively low costs. To compare the efficacy and safety between calcium carbonate and calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients. PubMed, EMBASE, Cochrane Library, Google scholar and Chinese databases (Wanfang, Weipu, National Knowledge Infrastructure of China) were searched for relevant studies published before March 2014. Reference lists of nephrology textbooks and review articles were checked. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of calcium acetate and calcium carbonate in adult patients with MHD was performed using Review Manager 5.0. A total of ten studies (625 participants) were included in this meta-analysis. There was insufficient data in all-cause mortality and cardiovascular events for meta-analysis. Compared with calcium carbonate group, the serum phosphorus was significantly lower in calcium acetate group after4 weeks' administration (MD -0.15 mmol/L, 95% CI -0.28 to -0.01) and after 8 weeks' administration (MD -0.25 mmol/L, 95% CI -0.40 to -0.11). There was no difference in serum calcium levels or the incidence of hypercalcemia between two groups at 4 weeks and 8 weeks. No statistical difference was found in parathyroid hormone (PTH) levels or serum calcium by phosphorus (Ca x P) product. There was significantly higher risk of intolerance with calcium acetate treatment (RR 3.46, 95% CI 1.48 to 8.26). For hyperphosphatemia treatment, calcium acetate showed better efficacy and with a higher incidence of intolerance compared with calcium carbonate. There are insufficient data to establish the comparative superiority of the two calcium-based phosphate binders on all-cause mortality and cardiovascular end-points in hemodialysis patients.

Effect of calcium source on structure and properties of sol-gel derived bioactive glasses.

PubMed

Yu, Bobo; Turdean-Ionescu, Claudia A; Martin, Richard A; Newport, Robert J; Hanna, John V; Smith, Mark E; Jones, Julian R

2012-12-18

The aim was to determine the most effective calcium precursor for synthesis of sol-gel hybrids and for improving homogeneity of sol-gel bioactive glasses. Sol-gel derived bioactive calcium silicate glasses are one of the most promising materials for bone regeneration. Inorganic/organic hybrid materials, which are synthesized by incorporating a polymer into the sol-gel process, have also recently been produced to improve toughness. Calcium nitrate is conventionally used as the calcium source, but it has several disadvantages. Calcium nitrate causes inhomogeneity by forming calcium-rich regions, and it requires high temperature treatment (>400 °C) for calcium to be incorporated into the silicate network. Nitrates are also toxic and need to be burnt off. Calcium nitrate therefore cannot be used in the synthesis of hybrids as the highest temperature used in the process is typically 40-60 °C. Therefore, a different precursor is needed that can incorporate calcium into the silica network and enhance the homogeneity of the glasses at low (room) temperature. In this work, calcium methoxyethoxide (CME) was used to synthesize sol-gel bioactive glasses with a range of final processing temperatures from 60 to 800 °C. Comparison is made between the use of CME and calcium chloride and calcium nitrate. Using advanced probe techniques, the temperature at which Ca is incorporated into the network was identified for 70S30C (70 mol % SiO(2), 30 mol % CaO) for each of the calcium precursors. When CaCl(2) was used, the Ca did not seem to enter the network at any of the temperatures used. In contrast, Ca from CME entered the silica network at room temperature, as confirmed by X-ray diffraction, (29)Si magic angle spinning nuclear magnetic resonance spectroscopy, and dissolution studies. CME should be used in preference to calcium salts for hybrid synthesis and may improve homogeneity of sol-gel glasses.

Cell-type-specific modelling of intracellular calcium signalling: a urothelial cell model.

PubMed

Appleby, Peter A; Shabir, Saqib; Southgate, Jennifer; Walker, Dawn

2013-09-06

Calcium signalling plays a central role in regulating a wide variety of cell processes. A number of calcium signalling models exist in the literature that are capable of reproducing a variety of experimentally observed calcium transients. These models have been used to examine in more detail the mechanisms underlying calcium transients, but very rarely has a model been directly linked to a particular cell type and experimentally verified. It is important to show that this can be achieved within the general theoretical framework adopted by these models. Here, we develop a framework designed specifically for modelling cytosolic calcium transients in urothelial cells. Where possible, we draw upon existing calcium signalling models, integrating descriptions of components known to be important in this cell type from a number of studies in the literature. We then add descriptions of several additional pathways that play a specific role in urothelial cell signalling, including an explicit ionic influx term and an active pumping mechanism that drives the cytosolic calcium concentration to a target equilibrium. The resulting one-pool model of endoplasmic reticulum (ER)-dependent calcium signalling relates the cytosolic, extracellular and ER calcium concentrations and can generate a wide range of calcium transients, including spikes, bursts, oscillations and sustained elevations in the cytosolic calcium concentration. Using single-variate robustness and multivariate sensitivity analyses, we quantify how varying each of the parameters of the model leads to changes in key features of the calcium transient, such as initial peak amplitude and the frequency of bursting or spiking, and in the transitions between bursting- and plateau-dominated modes. We also show that, novel to our urothelial cell model, the ionic and purinergic P2Y pathways make distinct contributions to the calcium transient. We then validate the model using human bladder epithelial cells grown in monolayer cell culture and show that the model robustly captures the key features of the experimental data in a way that is not possible using more generic calcium models from the literature.

Transcriptome wide identification and validation of calcium sensor gene family in the developing spikes of finger millet genotypes for elucidating its role in grain calcium accumulation.

PubMed

Singh, Uma M; Chandra, Muktesh; Shankhdhar, Shailesh C; Kumar, Anil

2014-01-01

In finger millet, calcium is one of the important and abundant mineral elements. The molecular mechanisms involved in calcium accumulation in plants remains poorly understood. Transcriptome sequencing of genetically diverse genotypes of finger millet differing in grain calcium content will help in understanding the trait. In this study, the transcriptome sequencing of spike tissues of two genotypes of finger millet differing in their grain calcium content, were performed for the first time. Out of 109,218 contigs, 78 contigs in case of GP-1 (Low Ca genotype) and out of 120,130 contigs 76 contigs in case of GP-45 (High Ca genotype), were identified as calcium sensor genes. Through in silico analysis all 82 unique calcium sensor genes were classified into eight calcium sensor gene family viz., CaM & CaMLs, CBLs, CIPKs, CRKs, PEPRKs, CDPKs, CaMKs and CCaMK. Out of 82 genes, 12 were found diverse from the rice orthologs. The differential expression analysis on the basis of FPKM value resulted in 24 genes highly expressed in GP-45 and 11 genes highly expressed in GP-1. Ten of the 35 differentially expressed genes could be assigned to three documented pathways involved mainly in stress responses. Furthermore, validation of selected calcium sensor responder genes was also performed by qPCR, in developing spikes of both genotypes grown on different concentration of exogenous calcium. Through de novo transcriptome data assembly and analysis, we reported the comprehensive identification and functional characterization of calcium sensor gene family. The calcium sensor gene family identified and characterized in this study will facilitate in understanding the molecular basis of calcium accumulation and development of calcium biofortified crops. Moreover, this study also supported that identification and characterization of gene family through Illumina paired-end sequencing is a potential tool for generating the genomic information of gene family in non-model species.

Hypoparathyroidism: what is the best calcium carbonate supplementation intake form?

PubMed

Gollino, Loraine; Biagioni, Maria Fernanda Giovanetti; Sabatini, Nathalia Regina; Tagliarini, José Vicente; Corrente, José Eduardo; Paiva, Sérgio Alberto Rupp de; Mazeto, Gláucia Maria Ferreira da Silva

2017-11-15

In hypoparathyroidism, calcium supplementation using calcium carbonate is necessary for the hypocalcemia control. The best calcium carbonate intake form is unknown, be it associated with feeding, juice or in fasting. The objective was to evaluate the calcium, phosphorus and Calcium×Phosphorus product serum levels of hypoparathyroidism women after total thyroidectomy, following calcium carbonate intake in three different forms. A crossover study was carried out with patients presenting definitive hypoparathyroidism, assessed in different situations (fasting, with water, orange juice, breakfast with a one-week washout). Through the review of clinical data records of tertiary hospital patients from 1994 to 2010, 12 adult women (18 50 years old) were identified and diagnosed with definitive post-thyroidectomy hypoparathyroidism. The laboratory results of calcium and phosphorus serum levels dosed before and every 30min were assessed, for 5h, after calcium carbonate intake (elementary calcium 500mg). The maximum peak average values for calcium, phosphorus and Calcium×Phosphorus product were 8.63mg/dL (water), 8.77mg/dL (orange juice) and 8.95mg/dL (breakfast); 4.04mg/dL (water), 4.03mg/dL (orange juice) and 4.12mg/dL (breakfast); 34.3mg 2 /dL 2 (water), 35.8mg 2 /dL 2 (orange juice) and 34.5mg 2 /dL 2 (breakfast), respectively, and the area under the curve 2433mg/dLmin (water), 2577mg/dLmin (orange juice) and 2506mg/dLmin (breakfast), 1203mg/dLmin (water), 1052mg/dLmin (orange juice) and 1128mg/dLmin (breakfast), respectively. There was no significant difference among the three different tests (p>0.05). The calcium, phosphorus and Calcium×Phosphorus product serum levels evolved in a similar fashion in the three calcium carbonate intake forms. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Individual and family correlates of calcium-rich food intake among parents of early adolescent children.

PubMed

Reicks, Marla; Ballejos, Miriam Edlefsen; Goodell, L Suzanne; Gunther, Carolyn; Richards, Rickelle; Wong, Siew Sun; Auld, Garry; Boushey, Carol J; Bruhn, Christine; Cluskey, Mary; Misner, Scottie; Olson, Beth; Zaghloul, Sahar

2011-03-01

Most adults do not meet calcium intake recommendations. Little is known about how individual and family factors, including parenting practices that influence early adolescents' intake of calcium-rich foods, affect calcium intake of parents. This information could inform the development of effective nutrition education programs. To identify individual and family factors associated with intake of calcium-rich foods among parents of early adolescents (aged 10 to 13 years). A cross-sectional survey was used with 14 scales to assess attitudes/preferences and parenting practices regarding calcium-rich foods and a calcium-specific food frequency questionnaire (2006-2007). A convenience sample of self-reporting non-Hispanic white, Hispanic, and Asian (n=661) parents was recruited in nine states. Parents were the primary meal planner/preparer and completed questionnaires in homes or community settings. Predictors of calcium intake from three food groupings-all food sources, dairy foods, and milk. Multivariate regression analyses identified demographic, attitude/preference, and behavioral factors associated with calcium intake. Most respondents were women (∼90%) and 38% had a college degree. Education was positively associated with calcium intake from all three food groupings, whereas having an Asian spouse compared to a non-Hispanic white spouse was negatively associated with calcium intake only from all food sources and from dairy foods. Expectations for and encouragement of healthy beverage intake for early adolescents were positively associated with calcium intake from dairy foods and milk, respectively. Parental concern regarding adequacy of intake was negatively associated, whereas perception of health benefits from calcium-rich foods was positively associated with calcium intake from all food sources and from dairy foods. Between 20% and 32% of the variance in calcium intake from all food groupings was explained in these models. Individual factors and positive parenting practices may be important considerations for nutrition education programs targeted to parents. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

Association of urinary calcium excretion with serum calcium and vitamin D levels.

PubMed

Rathod, Anita; Bonny, Olivier; Guessous, Idris; Suter, Paolo M; Conen, David; Erne, Paul; Binet, Isabelle; Gabutti, Luca; Gallino, Augusto; Muggli, Franco; Hayoz, Daniel; Péchère-Bertschi, Antoinette; Paccaud, Fred; Burnier, Michel; Bochud, Murielle

2015-03-06

Population-based data on urinary calcium excretion are scarce. The association of serum calcium and circulating levels of vitamin D [25(OH)D2 or D3] with urinary calcium excretion in men and women from a population-based study was explored. Multivariable linear regression was used to explore factors associated with square root-transformed 24-hour urinary calcium excretion (milligrams per 24 hours) taken as the dependent variable with a focus on month-specific vitamin D tertiles and serum calcium in the Swiss Survey on Salt Study. In total, 624 men and 669 women were studied with mean ages of 49.2 and 47.0 years, respectively (age range=15-95 years). Mean urinary calcium excretion was higher in men than in women (183.05 versus 144.60 mg/24 h; P<0.001). In adjusted models, the association (95% confidence interval) of square root urinary calcium excretion with protein-corrected serum calcium was 1.78 (95% confidence interval, 1.21 to 2.34) mg/24 h per milligram per deciliter in women and 0.59 (95% confidence interval, -0.11 to 1.29) mg/24 h per milligram per deciliter in men. Men in the third 25(OH)D3 tertile had higher square root urinary calcium excretion than men in the first tertile (0.99; 95% confidence interval, 0.36 to 1.63 mg/24 h per nanogram per milliliter), and the corresponding association was 0.32 (95% confidence interval, -0.22 to 0.85) mg/24 h per nanogram per milliliter in women. These sex differences were more marked under conditions of high urinary sodium or urea excretions. There was a positive association of serum calcium with urinary calcium excretion in women but not men. Vitamin 25(OH)D3 was associated with urinary calcium excretion in men but not women. These results suggest important sex differences in the hormonal and dietary control of urinary calcium excretion. Copyright © 2015 by the American Society of Nephrology.

Calcium translocations during the moulting cycle of the semiterrestrial isopod Ligia hawaiiensis (Oniscidea, Crustacea).

PubMed

Ziegler, Andreas; Hagedorn, Monica; Ahearn, Gregory A; Carefoot, Thomas H

2007-01-01

Terrestrial isopods moult first the posterior and then the anterior half of the body. During the moulting cycle they retain a significant fraction of cuticular calcium partly by storing it in sternal CaCO(3) deposits. We analysed the calcium content in whole Ligia hawaiiensis and the calcium distribution between the posterior, the anterior ventral, and the anterior dorsal cuticle during four stages of the moulting cycle. The results indicate that: (1) overall, about 80% of the calcium is retained and 20% is lost with the exuviae, (2) in premoult 68% of the calcium in the posterior cuticle is resorbed (23% moved to the anterior ventral cuticle, 17% to the anterior dorsal cuticle, and the remaining 28% to internal tissues), (3) after the posterior moult 83% of the calcium in the anterior cuticle is shifted to the posterior cuticle and possibly to internal storage sites, (4) following the anterior moult up to 54% of the calcium in the posterior cuticle is resorbed and used to mineralise the new anterior cuticle. (45)Ca-uptake experiments suggest that up to 80% of calcium lost with the anterior exuviae may be regained after its ingestion. Whole body calcium of Ligia hawaiiensis is only 0.7 times that of the fully terrestrial isopods. These terrestrial species can retain only 48% of whole body calcium, suggesting that the amount of calcium that can be retained by shifting it between the anterior and posterior integument is limited. We propose that fully terrestrial Oniscidea rely to a larger degree on other calcium sources like internal stores and uptake from the ingested exuviae.

Calcium binding to Procambarus clarkii sarcoplasmic calcium binding protein splice variants.

PubMed

Rohrback, Suzanne E; Wheatly, Michele G; Gillen, Christopher M

2015-01-01

Sarcoplasmic calcium binding protein (SCP) is a high-affinity calcium buffering protein expressed in muscle of crayfish and other invertebrates. In previous work, we identified three splice variants of Procambarus clarkii SCP (pcSCP1a, pcSCP1b, and pcSCP1c) that differ in a 37 amino acid region that lies mainly between the 2nd and 3ed EF-hand calcium binding domain. To evaluate the function of the proteins encoded by the pcSCP1 transcripts, we produced recombinant pcSCP1 and used tryptophan fluorescence to characterize calcium binding. Tryptophan fluorescence of pcSCP1a decreased in response to increased calcium, while tryptophan fluorescence of the pcSCP1b and pcSCP1c variants increased. We estimated calcium binding constants and Hill coefficients with two different equations: the standard Hill equation and a modified Hill equation that accounts for contributions from two different tryptophans. The approaches gave similar results. Steady-state calcium binding constants (Kd) ranged from 2.7±0.7×10(-8)M to 5.6±0.1×10(-7)M, consistent with previous work. Variants displayed significantly different apparent calcium affinities, which were decreased in the presence of magnesium. Calcium Kd was lowest for pcSCP1a and highest for pcSCP1c. Site-directed mutagenesis of pcSCP1c residues to the amino acids of pcSCP1b decreased the calcium Kd, identifying residues outside the EF-hand domains that contribute to calcium binding in crayfish SCP. Copyright © 2014 Elsevier Inc. All rights reserved.

Best time window for the use of calcium-modulating agents to improve functional recovery in injured peripheral nerves-An experiment in rats.

PubMed

Yan, Yuhui; Shen, Feng-Yi; Agresti, Michael; Zhang, Lin-Ling; Matloub, Hani S; LoGiudice, John A; Havlik, Robert; Li, Jifeng; Gu, Yu-Dong; Yan, Ji-Geng

2017-09-01

Peripheral nerve injury can have a devastating effect on daily life. Calcium concentrations in nerve fibers drastically increase after nerve injury, and this activates downstream processes leading to neuron death. Our previous studies showed that calcium-modulating agents decrease calcium accumulation, which aids in regeneration of injured peripheral nerves; however, the optimal therapeutic window for this application has not yet been identified. In this study, we show that calcium clearance after nerve injury is positively correlated with functional recovery in rats suffering from a crushed sciatic nerve injury. After the nerve injury, calcium accumulation increased. Peak volume is from 2 to 8 weeks post injury; calcium accumulation then gradually decreased over the following 24-week period. The compound muscle action potential (CMAP) measurement from the extensor digitorum longus muscle recovered to nearly normal levels in 24 weeks. Simultaneously, real-time polymerase chain reaction results showed that upregulation of calcium-ATPase (a membrane protein that transports calcium out of nerve fibers) mRNA peaked at 12 weeks. These results suggest that without intervention, the peak in calcium-ATPase mRNA expression in the injured nerve occurs after the peak in calcium accumulation, and CMAP recovery continues beyond 24 weeks. Immediately using calcium-modulating agents after crushed nerve injury improved functional recovery. These studies suggest that a crucial time frame in which to initiate effective clinical approaches to accelerate calcium clearance and nerve regeneration would be prior to 2 weeks post injury. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A study of calcium intake and sources of calcium in adolescent boys and girls from two socioeconomic strata, in Pune, India.

PubMed

Sanwalka, Neha J; Khadilkar, Anuradha V; Mughal, M Zulf; Sayyad, Mehmood G; Khadilkar, Vaman V; Shirole, Shilpa C; Divate, Uma P; Bhandari, Dhanshari R

2010-01-01

Adequate intake of calcium is important for skeletal growth. Low calcium intake during childhood and adolescence may lead to decreased bone mass accrual thereby increasing the risk of osteoporotic fractures. Our aim was to study dietary calcium intake and sources of calcium in adolescents from lower and upper economic strata in Pune, India. We hypothesized that children from lower economic strata would have lower intakes of calcium, which would predominantly be derived from non-dairy sources. Two hundred male and female adolescents, from lower and upper economic stratum were studied. Semiquantitative food frequency questionnaire was used to evaluate intakes of calcium, phosphorus, oxalic acid, phytin, energy and protein. The median calcium intake was significantly different in all four groups, with maximum intake in the upper economic strata boys (893 mg, 689-1295) and lowest intake in lower economic strata girls (506 mg, 380-674). The median calcium intake in lower economic strata boys was 767 mg (585-1043) and that in upper economic strata girls was 764 mg (541-959). The main source of calcium was dairy products in upper economic strata adolescents while it was dark green leafy vegetables in lower economic strata adolescents. The median calcium intake was much lower in lower economic strata than in the upper economic strata both in boys and girls. Girls from both groups had less access to dairy products as compared to boys. Measures need to be taken to rectify low calcium intake in lower economic strata adolescents and to address gender inequality in distribution of dairy products in India.

Changes in extracellular calcium activity during gravity sensing in maize roots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bjoerkman, T.; Cleland, R.E.

1990-05-01

A redistribution of calcium downward across the root cap has been proposed as an essential part of gravitropism in roots. Exogenous {sup 45}Ca moves preferentially downward across gravistimulated maize root tips. However, because of the many calcium-binding sites in the apoplast, this might not result in a physiologically effect change in the apoplasmic calcium activity. To test whether there is such a change, we measured the effect of gravistimulation on the calcium activity with calcium-specific microelectrodes. Decapped maize roots (Zea mays L. cv. Golden Cross Bantam) were grown for 31 h to regenerate gravitropic sensitivity, but not root caps. Themore » calcium activity in the apoplasm surrounding the gravity-sensing cells could then be measured. The initial pCa was 2.60 {plus minus} 0.28 (approx 2.5 mM). The calcium activity on the upper side of the root tip remained constant for about five minutes after gravistimulation, then decreased by about one half. On the lower side, after a similar lag the calcium activity doubled. Control roots, which were decapped but measured before recovering gravisensitivity (19 h), showed no change in calcium activity. We have found a distinct and rapid differential in the apoplasmic calcium activity between the upper and lower sides of gravistimulated maize root tips.« less

On the role of calcium in adrenocorticotropin-induced changes in mitochondrial pregnenolone synthesis.

PubMed

Farese, R V; Prudente, W J

1978-10-01

The importance of calcium in the ACTH-induced increase in adrenal mitochondrial pregnenolone synthesis was evaluated. In mitochondria prepared in the absence of EDTA and albumin, calcium enhanced the binding of cholesterol to cytochrome P-450 and subsequent pregnenolone synthesis. Although these effects of calcium were slightly greater in control than in ACTH-treated mitochondria, a sizeable effect of ACTH remained even at high calcium levels (500 micron). In mitochondria prepared from adrenals homogenized in fluid containing EDTA and albumin, ACTH-induced effects on pregnenolone synthesis were relatively poor unless calcium was added to the incubation mixture. High concentrations of added calcium (500 micron or greater) obviated the need for the labile protein required for ACTH-induced effects in intact mitochondria, presumably by disrupting mitochondria and allowing an "unrestrained" interaction of cholesterol with cytochrome P-450. Thus, cholesterol-rich mitochondria from ACTH plus cycloheximide-treated rats produced large amounts of pregnenolone when high (probably unphysiological) calcium concentrations were present. The present findings suggest that calcium is required at the mitochondrial level for ACTH-induced effects on pregnenolone synthesis, and the reported ACTH-induced increase in intraadrenal calcium may thus amplify the effects of ACTH on steroidogenesis. However, it seems unlikely that calcium is the agent primarily responsible for mediating the ACTH-induced steroidogenic effect at the mitochondrial level.

Calcium in the prevention of postmenopausal osteoporosis: EMAS clinical guide.

PubMed

Cano, Antonio; Chedraui, Peter; Goulis, Dimitrios G; Lopes, Patrice; Mishra, Gita; Mueck, Alfred; Senturk, Levent M; Simoncini, Tommaso; Stevenson, John C; Stute, Petra; Tuomikoski, Pauliina; Rees, Margaret; Lambrinoudaki, Irene

2018-01-01

Postmenopausal osteoporosis is a highly prevalent disease. Prevention through lifestyle measures includes an adequate calcium intake. Despite the guidance provided by scientific societies and governmental bodies worldwide, many issues remain unresolved. To provide evidence regarding the impact of calcium intake on the prevention of postmenopausal osteoporosis and critically appraise current guidelines. Literature review and consensus of expert opinion. The recommended daily intake of calcium varies between 700 and 1200mg of elemental calcium, depending on the endorsing source. Although calcium can be derived either from the diet or supplements, the former source is preferred. Intake below the recommended amount may increase fragility fracture risk; however, there is no consistent evidence that calcium supplementation at, or above, recommended levels reduces risk. The addition of vitamin D may minimally reduce fractures, mainly among institutionalised people. Excessive intake of calcium, defined as higher than 2000mg/day, can be potentially harmful. Some studies demonstrated harm even at lower dosages. An increased risk for cardiovascular events, urolithiasis and even fractures has been found in association with excessive calcium intake, but this issue remains unresolved. In conclusion, an adequate intake of calcium is recommended for general bone health. Excessive calcium intake seems of no benefit, and could possibly be harmful. Copyright © 2017 Elsevier B.V. All rights reserved.

Increased calcium absorption from synthetic stable amorphous calcium carbonate: double-blind randomized crossover clinical trial in postmenopausal women.

PubMed

Vaisman, Nachum; Shaltiel, Galit; Daniely, Michal; Meiron, Oren E; Shechter, Assaf; Abrams, Steven A; Niv, Eva; Shapira, Yami; Sagi, Amir

2014-10-01

Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (CCC) using the dual stable isotope technique. The study was conducted in the Unit of Clinical Nutrition, Tel Aviv Sourasky Medical Center, Israel. The study population included 15 early postmenopausal women aged 54.9 ± 2.8 (mean ± SD) years with no history of major medical illness or metabolic bone disorder, excess calcium intake, or vitamin D deficiency. Standardized breakfast was followed by randomly provided CCC or ACC capsules containing 192 mg elemental calcium labeled with 44Ca at intervals of at least 3 weeks. After swallowing the capsules, intravenous CaCl2 labeled with 42Ca on was administered on each occasion. Fractional calcium absorption (FCA) of ACC and CCC was calculated from the 24-hour urine collection following calcium administration. The results indicated that FCA of ACC was doubled (± 0.96 SD) on average compared to that of CCC (p < 0.02). The higher absorption of the synthetic stable ACC may serve as a more efficacious way of calcium supplementation. © 2014 American Society for Bone and Mineral Research.

Plating and stripping calcium in an organic electrolyte

NASA Astrophysics Data System (ADS)

Wang, Da; Gao, Xiangwen; Chen, Yuhui; Jin, Liyu; Kuss, Christian; Bruce, Peter G.

2018-01-01

There is considerable interest in multivalent cation batteries, such as those based on magnesium, calcium or aluminium. Most attention has focused on magnesium. In all cases the metal anode represents a significant challenge. Recent work has shown that calcium can be plated and stripped, but only at elevated temperatures, 75 to 100 °C, with small capacities, typically 0.165 mAh cm-2, and accompanied by significant side reactions. Here we demonstrate that calcium can be plated and stripped at room temperature with capacities of 1 mAh cm-2 at a rate of 1 mA cm-2, with low polarization (~100 mV) and in excess of 50 cycles. The dominant product is calcium, accompanied by a small amount of CaH2 that forms by reaction between the deposited calcium and the electrolyte, Ca(BH4)2 in tetrahydrofuran (THF). This occurs in preference to the reactions which take place in most electrolyte solutions forming CaCO3, Ca(OH)2 and calcium alkoxides, and normally terminate the electrochemistry. The CaH2 protects the calcium metal at open circuit. Although this work does not solve all the problems of calcium as an anode in calcium-ion batteries, it does demonstrate that significant quantities of calcium can be plated and stripped at room temperature with low polarization.

Influence of calcium precursors on the morphology and crystallinity of sol gel-derived hydroxyapatite nanoparticles

NASA Astrophysics Data System (ADS)

Vijayalakshmi Natarajan, U.; Rajeswari, S.

2008-10-01

Nanosized hydroxyapatite (HAP) particles were prepared by sol-gel method from the water-based solution of calcium and phosphorus precursor. In this study, two calcium precursors such as calcium nitrate tetrahydrate and calcium acetate were chosen as calcium precursors. The influence of aging period, pH, viscosity and sintering temperature on crystallinity and morphology of the HAP particles were investigated for the two calcium precursors with triethyl phosphate precursor. The morphology of nano-HAP towards phosphorous precursor was dependent on the type of calcium precursor used. The HAP prepared from calcium nitrate and triethyl phosphate was spherically shaped whereas the one from calcium acetate was found to be fibrous in structure. Both HAPs were stable up to 1200 °C and their crystallinity increased with respect to the sintering temperature. The obtained sample was characterized through X-ray diffraction (XRD), P 31 nuclear magnetic resonance (NMR), scanning electronic microscopy (SEM) and TEM analysis. The sol derived from the optimized aging period for the two different calcium precursors was coated on 316L stainless-steel (SS) implant and its corrosion resistivity during long-term implantation was studied by cyclic polarization in Ringer's solution. Both HAPs have their own desirable qualities and were found to be corrosion resistive.

Effect of Reaction Pathway on the Extent and Mechanism of Uranium(VI) Immobilization with Calcium and Phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, Vrajesh S.; Maillot, Fabien; Wang, Zheming

Phosphate addition to subsurface environments contaminated with uranium can be used as an in situ remediation approach. Batch experiments were conducted to evaluate the dependence of the extent and mechanism of uranium uptake on the pathway for reaction with calcium phosphates. At pH 4.0 and 6.0 uranium uptake occurred via autunite (Ca(UO2)(PO4)3) precipitation irrespective of the starting forms of calcium and phosphate. At pH 7.5, the uptake mechanism depended on the nature of the calcium and phosphate. When dissolved uranium, calcium, and phosphate were added simultaneously, uranium was structurally incorporated into a newly formed amorphous calcium phosphate solid. Adsorption wasmore » the dominant removal mechanism for uranium contacted with pre-formed amorphous calcium phosphate solids,. When U(VI) was added to a suspension containing amorphous calcium phosphate solids as well as dissolved calcium and phosphate, then removal occurred through precipitation (57±4 %) of autunite and adsorption (43±4 %) onto calcium phosphate. The solid phase speciation of the uranium was determined using X-ray absorption spectroscopy and laser induced fluorescence spectroscopy. Dissolved uranium, calcium, and phosphate concentrations with saturation index calculations helped identify removal mechanisms and determine thermodynamically favorable solid phases.« less

Conversion of alkali metal sulfate to the carbonate

DOEpatents

Sheth, A.C.

1979-10-01

A process is described for converting potassium sulfate to potassium carbonate in which a mixture of potassium sulfate and calcium oxide are reacted at a temperature in the range of between about 700/sup 0/C and about 800/sup 0/C with a gaseous mixture having a minor amount of hydrogen and/or carbon monoxide in a diluent with the calcium oxide being present in an amount not greater than about 20 percent by weight of the potassium sulfate to produce an aqueous mixture of potassium sulfide, potassium bisulfide, potassium hydroxide and calcium sulfide and a gaseous mixture of steam and hydrogen sulfide. The potassium and calcium salts are quenched to produce an aqueous slurry of soluble potassium salts and insoluble calcium salts and a gaseous mixture of steam and hydrogen sulfide. The insoluble calcium salts are then separated from the aqueous solution of soluble potassium salts. The calcium salts are dried to produce calcium sulfide, calcium bisulfide and steam, and then, the calcium sulfide and calcium bisulfide are converted to the oxide and recycled. The soluble potassium salts are carbonated to produce potassium carbonate which is concentrated and the precipitated crystals separated. the sulfur-containing compounds are further treated. This process was developed for desulfurization and reprocessing of spent seed from open-cycle coal-fired MHD generators for reuse.

A comparison of the effects of commercially available hawthorn preparations on calcium transients of isolated cardiomyocytes.

PubMed

Rodriguez, Michelle E; Poindexter, Brian J; Bick, Roger J; Dasgupta, Amitava

2008-12-01

We studied the potential cardiac effects of two alcohol extracts of commercially available hawthorn using rat cardiomyocytes and measuring calcium transients by real-time fluorescence spectrophotometry. One preparation was a blend of hawthorn flowers, leaves, and berries (extract #1), and the other (extract #2) was from a "berries-only" preparation. Fluorescent images and calcium transients were acquired concurrently. Addition of extract #1 resulted in the initiation of robust calcium transients and eventual calcium overload, while addition of extract #2 caused increased calcium sparking, initiation of calcium transients, and an increased beating rate but no calcium overload. To identify the mechanisms of increased calcium influx, adult rat cardiomyocytes were challenged with 10 microM ouabain, a Na(+),K(+)-ATPase inhibitor, and the calcium channel blocker nifedipine. The findings revealed that equal volumes of the two readily available hawthorn preparations demonstrated markedly different effects on isolated adult rat cardiomyocytes, suggesting important implications for patients who are using these preparations to supplement or even replace their prescribed cardiac medications as to which preparation(s) to use, and potential dire consequences, particularly in cardiac patients. Our study indicates that the mechanism of cardiac activity of hawthorn is via the Na(+),K(+)-ATPase and intracellular calcium concentrations are influenced.

Calcium and bones (image)

MedlinePlus

Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

Tests of the relative roles of calcium channels and calcium pumps in controlling gravity-directed development in single spore cells of the fern Ceratopteris richardii

NASA Astrophysics Data System (ADS)

Roux, Stanley; Porterfield, D. Marshall; Haque, Aeraj Ul; Bushart, Thomas

The vector of gravity sets the direction of polarized development of single spore cells of the fern Ceratopteris richardii after light initiates their germination. Gravity also sets the direction of a trans-cell calcium current, which enters the cell along its bottom and exits it from its top. The direction of this current predicts the subsequent direction of spore development, and blocking this current with calcium channel blockers randomizes the direction of subsequent development. Recently the laboratory of D. Marshall Porterfield (Purdue University) developed a microchip device that can measure the direction and magnitude of the trans-spore calcium current in real time. Our laboratory in collaboration with Porterfield's recently found that this current inverts rapidly when the cells are turned upside down and that the magnitude of the current rises and falls with the magnitude of the g-force when these cells are tested in parabolic flight on the DC-9 aircraft. We assume that the gravity-directed entry of calcium into these cells is through calcium channels and its exit is through calcium pumps. Here we report our studies of a calcium pump that is highly expressed in the spores during the period when gravity is setting the direction of the calcium current, and we describe pharmacological tests of the relative importance of calcium pumps in maintaining the calcium current and in controlling the direction of subsequent spore development. We found that inhibitors that block the activity of calcium pumps also greatly depress the trans-cell current, but, surprisingly, have little effect on the ability of gravity to set the direction of spore development. These results, in combination with earlier findings, indicate that the gravity-directed opening of calcium channels along the bottom of spore cells plays a more important role in directing subsequent spore development than the activity of calcium pumps, despite the importance of these pumps in maintaining the trans-cell calcium current. Supported by NASA grants NAG2-1586 and NAG10-295 to S. J. R.

[Studies on the calcium distribution in developing synergids of lettuce (Lactuca sativa L.)].

PubMed

Qiu, Yi Lan; Liu, Ru Shi; Tian, Hui Qiao

2007-08-01

Potassium antimonite was used to locate calcium in the synergids of lettuce (Lactuca sativa L) during their development. The two synergids on 3d before anthesis formed evident polarity with most cytoplasm located in the micropylar end and nucleus in the middle and a big vacuole in the chalazal end. At this time, calcium precipitates were a few in both cells. Calcium precipitates in the two synergids began to increase on 2d before anthesis. Synergid wall in the micropylar end thickened on 1d before anthesis, in which many calcium precipitates located. Near anthesis, synergids formed filiform apparatus in which abundant calcium precipitates accumulated to prepare for attracting pollen tubes entering. At anthesis, the distribution of calcium precipitates between two synergids was the same. At 1h after pollination, calcium precipitates evidently increased in one synergid that seemed to degenerate, the other one was persistent and the distribution of calcium granules did not change. Two synergids kept intact at 1d after emasculated, and the distribution of calcium precipitates did not display difference, suggesting that the degeneration of one synergid was caused by approaching pollen tubes which might give some signal to induce calcium increase of the synergid. Before fusion of sperm cell with egg cell, the cytoplasm of degenerated synergid embraced the egg and formed a thin layer between the egg and the central cell. Calcium precipitates in the different parts of degenerated synergid were closely connected with the fertilization: calcium precipitates accumulated in the near chalazal end of degenerated synergid at 1h after pollination. At 2.5h after pollination, the calcium precipitates increased at the chalazal end, especially abundant in the thin layer between the egg and the central cell. However, at 4h after pollination, the fertilization had finished at this time, the distribution of calcium precipitates in degenerated synergid changed again: the precipitates decreased at the chalazal end and increased at the micropylar end. The above-mentioned results suggested that calcium in the degenerated synergid played an important role during lettuce fertilization.

Determining attitudinal and behavioral factors concerning milk and dairy intake and their association with calcium intake in college students

PubMed Central

2018-01-01

BACKGROUND/OBJECTIVES Average intake of calcium among college students is below the recommended intake, and knowledge surrounding the attitudinal and behavioral factors that influence milk and dairy intake, a primary food source of calcium, is limited. The purpose of this study was to evaluate college students' attitudes and behaviors concerning milk and dairy consumption and their association with calcium intake. SUBJECTS/METHODS Participants were 1,730 undergraduate students who completed an online survey (SurveyMonkey) as part of baseline data collection for a social marketing dairy campaign. The online survey assessed attitudes and behaviors concerning milk and dairy intake, and calcium intake. Questions about milk- and dairy-related attitudes and behaviors were grouped into 14 factors using factor analysis. Predictors of calcium intake were then evaluated. RESULTS Median calcium intake across all participants was 928.6 mg/day, with males consuming higher calcium intakes than females (P < 0.001). Adjusted for gender, calcium intakes were most strongly (and positively) correlated with associating milk with specific eating occasions and availability (i.e., storing calcium-rich foods in one's dorm or apartment) (both P < 0.001). Other correlates of calcium intake included: positive-viewing milk as healthy (P = 0.039), having family members who drink milk) (P = 0.039), and taking calcium supplements (P = 0.056); and negative-parent rules concerning milk (P = 0.031) and viewing milk in dining halls negatively (P = 0.05). CONCLUSIONS Calcium intakes among college students enrolled in the current study was below the recommended dietary allowance of 1,000 mg/day, reinforcing the need for dietary interventions in this target population, especially females. Practitioners and researchers should consider the factors found here to impact calcium intake, particularly associating milk with specific eating occasions (e.g., milk with breakfast) and having calcium-rich foods available in the dorm room or apartment, as intervention strategies in future efforts aimed at promoting milk and dairy foods and beverages for improved calcium intake in college students. PMID:29629031

Risk of calcium oxalate nephrolithiasis in postmenopausal women supplemented with calcium or combined calcium and estrogen.

PubMed

Domrongkitchaiporn, Somnuek; Ongphiphadhanakul, Boonsong; Stitchantrakul, Wasana; Chansirikarn, Sirinthorn; Puavilai, Gobchai; Rajatanavin, Rajata

2002-02-26

Recent studies showed that postmenopausal women lost less bone mass when supplemented with calcium or estrogen therapy. However, the safety of the treatments in terms of the risk of calcium oxalate stone formation is unknown. We therefore conducted this study to determine the alteration in calcium oxalate supersaturation after calcium supplement or after combined calcium and estrogen therapy in postmenopausal osteoporotic women. Fifty-six postmenopausal women were enrolled in this study. All subjects were more than 10 years postmenopausal with vertebral or femoral osteoporosis by bone mineral density criteria. They were randomly allocated to receive either 625 mg of calcium carbonate (250 mg of elemental calcium) at the end of a meal three times a day (group A, n=26) or calcium carbonate in the same manner plus 0.625 mg/day of conjugated equine estrogen and 5 mg medrogestone acetate from day 1-12 each month (group B, n=30). The age (mean +/- S.E.M.) was 66.3 +/- 1.2 and 65.1 +/- 1.1 years, weight 54.1 +/- 1.2 and 55.3 +/- 2.1 kg, in group A and group B, respectively. Urine specimens (24-h) were collected at baseline and 3 months after treatment for the determination of calcium oxalate saturation by using Tiselius's index (AP(CaOx)) and calcium/citrate ratio. After 3 months of treatment, there was no significant alteration from baseline for urinary excretion of calcium, citrate and oxalate. Urinary phosphate excretion was significantly reduced (6.3 +/- 0.7 vs. 5.1 +/- 0.7 mmol/day for group A and 8.2 +/- 0.9 vs. 5.8 +/- 0.7 mmol/day for group B, P<0.05), whereas net alkaline absorption was significantly elevated (10.1 +/- 3.6 vs. 20.1 +/- 4.4 meq/day for group A and 4.8 +/- 3.2 vs. 19.9 +/- 3.6 meq/day for group B, P<0.05). Calcium/citrate ratio and AP(CaOx) determined at baseline were not different from the corresponding values after treatment in both groups; calcium/citrate: 10.1 +/- 3.1 vs. 10.1 +/- 2.5 for group A and 9.3 +/- 1.8 vs. 11.9 +/- 2.5 for group B and AP(CaOx): 1.1 +/- 0.1 vs. 1.3 +/- 0.2 for group A and 1.2 +/- 0.2 vs. 1.1 +/- 0.1 for group B. There were eight and nine patients with high AP(CaOx), or >2, at baseline and after treatment, respectively. Calcium supplement with a meal or combined calcium supplement and estrogen therapy is not associated with a significant increased risk of calcium oxalate stone formation in the majority of postmenopausal osteoporotic patients. Determination of urinary saturation for calcium oxalate after calcium and estrogen supplements, especially at the initial phase of treatment, may be helpful in the avoidance of nephrolithiasis.

Supplemental calcium nutrition improves tuber yield and quality of native potatoes in the Peruvian highlands

USDA-ARS?s Scientific Manuscript database

Potato tubers are known to be calcium deficient. This is because calcium moves with water and most water is transported to leaves and tubers being in soil do not have the draw for water and calcium. Calcium fertilizers are now routinely used to improve tuber quality and production in the US. Potatoe...

A Crash Course in Calcium Channels.

PubMed

Zamponi, Gerald W

2017-12-20

Much progress has been made in understanding the molecular physiology and pharmacology of calcium channels. Recently, there have been tremendous advances in learning about calcium channel structure and function through crystallography and cryo-electron microscopy studies. Here, I will give an overview of our knowledge about calcium channels, and highlight two recent studies that give important insights into calcium channel structure.

21 CFR 184.1221 - Calcium propionate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium propionate. 184.1221 Section 184.1221 Food... Specific Substances Affirmed as GRAS § 184.1221 Calcium propionate. (a) Calcium propionate (C6H10CaO4, CAS Reg. No. 4075-81-4) is the calcium salt of propionic acid. It occurs as white crystals or a...

21 CFR 184.1221 - Calcium propionate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium propionate. 184.1221 Section 184.1221 Food... Specific Substances Affirmed as GRAS § 184.1221 Calcium propionate. (a) Calcium propionate (C6H10CaO4, CAS Reg. No. 4075-81-4) is the calcium salt of propionic acid. It occurs as white crystals or a...

21 CFR 184.1210 - Calcium oxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium oxide. 184.1210 Section 184.1210 Food and... Substances Affirmed as GRAS § 184.1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8) is also known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or...

21 CFR 184.1205 - Calcium hydroxide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium hydroxide. 184.1205 Section 184.1205 Food... Specific Substances Affirmed as GRAS § 184.1205 Calcium hydroxide. (a) Calcium hydroxide (Ca(OH)2, CAS Reg. No. 1305-62-0) is also known as slaked lime or calcium hydrate. It is produced by the hydration of...

21 CFR 184.1210 - Calcium oxide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium oxide. 184.1210 Section 184.1210 Food and... Substances Affirmed as GRAS § 184.1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8) is also known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or...

Parents' Calcium Knowledge Is Associated with Parental Practices to Promote Calcium Intake among Parents of Early Adolescent Children

ERIC Educational Resources Information Center

Gunther, Carolyn W.; Rose, Angela M.; Bruhn, Christine; Cluskey, Mary; Reicks, Marla; Richards, Rickelle; Wong, Siew Sun; Boushey, Carol J.; Misner, Scottie; Olson, Beth

2015-01-01

The study reported here aimed to identify the relationship of parents' calcium knowledge with diet-related parental practices and determinants of calcium knowledge. A cross-sectional survey was conducted measuring parental practices, calcium knowledge, and demographics. A convenience sample of 599 racially/ethnically diverse parents of children…

21 CFR 184.1221 - Calcium propionate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium propionate. 184.1221 Section 184.1221 Food... GRAS § 184.1221 Calcium propionate. (a) Calcium propionate (C6H10CaO4, CAS Reg. No. 4075-81-4) is the calcium salt of propionic acid. It occurs as white crystals or a crystalline solid, possessing not more...

21 CFR 184.1221 - Calcium propionate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium propionate. 184.1221 Section 184.1221 Food... Specific Substances Affirmed as GRAS § 184.1221 Calcium propionate. (a) Calcium propionate (C6H10CaO4, CAS Reg. No. 4075-81-4) is the calcium salt of propionic acid. It occurs as white crystals or a...

21 CFR 184.1221 - Calcium propionate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium propionate. 184.1221 Section 184.1221 Food... Specific Substances Affirmed as GRAS § 184.1221 Calcium propionate. (a) Calcium propionate (C6H10CaO4, CAS Reg. No. 4075-81-4) is the calcium salt of propionic acid. It occurs as white crystals or a...

21 CFR 184.1229 - Calcium stearate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium stearate. 184.1229 Section 184.1229 Food... Specific Substances Affirmed as GRAS § 184.1229 Calcium stearate. (a) Calcium stearate (Ca(C17H35COO)2, CAS Reg. No. 1529-23-0) is the calcium salt of stearic acid derived from edible sources. It is prepared as...

21 CFR 184.1229 - Calcium stearate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium stearate. 184.1229 Section 184.1229 Food... Specific Substances Affirmed as GRAS § 184.1229 Calcium stearate. (a) Calcium stearate (Ca(C17H35COO)2, CAS Reg. No. 1529-23-0) is the calcium salt of stearic acid derived from edible sources. It is prepared as...

21 CFR 184.1210 - Calcium oxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium oxide. 184.1210 Section 184.1210 Food and....1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8) is also known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by calcination...

21 CFR 184.1199 - Calcium gluconate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium gluconate. 184.1199 Section 184.1199 Food... GRAS § 184.1199 Calcium gluconate. (a) Calcium gluconate ([CH2OH(CHOH)4COO]2Ca, CAS Reg. No. 299-28-5) is the calcium salt of gluconic acid which may be produced by neutralization of gluconic acid with...

21 CFR 184.1199 - Calcium gluconate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium gluconate. 184.1199 Section 184.1199 Food... Specific Substances Affirmed as GRAS § 184.1199 Calcium gluconate. (a) Calcium gluconate ([CH2OH(CHOH)4COO]2Ca, CAS Reg. No. 299-28-5) is the calcium salt of gluconic acid which may be produced by...

21 CFR 184.1199 - Calcium gluconate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium gluconate. 184.1199 Section 184.1199 Food... Specific Substances Affirmed as GRAS § 184.1199 Calcium gluconate. (a) Calcium gluconate ([CH2OH(CHOH)4COO]2Ca, CAS Reg. No. 299-28-5) is the calcium salt of gluconic acid which may be produced by...

21 CFR 184.1205 - Calcium hydroxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium hydroxide. 184.1205 Section 184.1205 Food... GRAS § 184.1205 Calcium hydroxide. (a) Calcium hydroxide (Ca(OH)2, CAS Reg. No. 1305-62-0) is also known as slaked lime or calcium hydrate. It is produced by the hydration of lime. (b) The ingredient...

Osteoporosis Knowledge, Calcium Intake, and Weight-Bearing Physical Activity in Three Age Groups of Women.

ERIC Educational Resources Information Center

Terrio, Kate; Auld, Garry W.

2002-01-01

Determined the extent and integration of osteoporosis knowledge in three age groups of women, comparing knowledge to calcium intake and weight bearing physical activity (WBPA). Overall calcium intake was relatively high. There were no differences in knowledge, calcium intake, or WBPA by age, nor did knowledge predict calcium intake and WBPA. None…

Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

ERIC Educational Resources Information Center

Henrickson, Charles H.; Robinson, Paul R.

1979-01-01

The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

The complex nature of calcium cation interactions with phospholipid bilayers

PubMed Central

Melcrová, Adéla; Pokorna, Sarka; Pullanchery, Saranya; Kohagen, Miriam; Jurkiewicz, Piotr; Hof, Martin; Jungwirth, Pavel; Cremer, Paul S.; Cwiklik, Lukasz

2016-01-01

Understanding interactions of calcium with lipid membranes at the molecular level is of great importance in light of their involvement in calcium signaling, association of proteins with cellular membranes, and membrane fusion. We quantify these interactions in detail by employing a combination of spectroscopic methods with atomistic molecular dynamics simulations. Namely, time-resolved fluorescent spectroscopy of lipid vesicles and vibrational sum frequency spectroscopy of lipid monolayers are used to characterize local binding sites of calcium in zwitterionic and anionic model lipid assemblies, while dynamic light scattering and zeta potential measurements are employed for macroscopic characterization of lipid vesicles in calcium-containing environments. To gain additional atomic-level information, the experiments are complemented by molecular simulations that utilize an accurate force field for calcium ions with scaled charges effectively accounting for electronic polarization effects. We demonstrate that lipid membranes have substantial calcium-binding capacity, with several types of binding sites present. Significantly, the binding mode depends on calcium concentration with important implications for calcium buffering, synaptic plasticity, and protein-membrane association. PMID:27905555

Initial stages of calcium uptake and mineral deposition in sea urchin embryos

PubMed Central

Vidavsky, Netta; Addadi, Sefi; Mahamid, Julia; Shimoni, Eyal; Ben-Ezra, David; Shpigel, Muki; Weiner, Steve; Addadi, Lia

2014-01-01

Sea urchin larvae have an endoskeleton consisting of two calcitic spicules. We reconstructed various stages of the formation pathway of calcium carbonate from calcium ions in sea water to mineral deposition and integration into the forming spicules. Monitoring calcium uptake with the fluorescent dye calcein shows that calcium ions first penetrate the embryo and later are deposited intracellularly. Surprisingly, calcium carbonate deposits are distributed widely all over the embryo, including in the primary mesenchyme cells and in the surface epithelial cells. Using cryo-SEM, we show that the intracellular calcium carbonate deposits are contained in vesicles of diameter 0.5–1.5 μm. Using the newly developed airSEM, which allows direct correlation between fluorescence and energy dispersive spectroscopy, we confirmed the presence of solid calcium carbonate in the vesicles. This mineral phase appears as aggregates of 20–30-nm nanospheres, consistent with amorphous calcium carbonate. The aggregates finally are introduced into the spicule compartment, where they integrate into the growing spicule. PMID:24344263

Initial stages of calcium uptake and mineral deposition in sea urchin embryos.

PubMed

Vidavsky, Netta; Addadi, Sefi; Mahamid, Julia; Shimoni, Eyal; Ben-Ezra, David; Shpigel, Muki; Weiner, Steve; Addadi, Lia

2014-01-07

Sea urchin larvae have an endoskeleton consisting of two calcitic spicules. We reconstructed various stages of the formation pathway of calcium carbonate from calcium ions in sea water to mineral deposition and integration into the forming spicules. Monitoring calcium uptake with the fluorescent dye calcein shows that calcium ions first penetrate the embryo and later are deposited intracellularly. Surprisingly, calcium carbonate deposits are distributed widely all over the embryo, including in the primary mesenchyme cells and in the surface epithelial cells. Using cryo-SEM, we show that the intracellular calcium carbonate deposits are contained in vesicles of diameter 0.5-1.5 μm. Using the newly developed airSEM, which allows direct correlation between fluorescence and energy dispersive spectroscopy, we confirmed the presence of solid calcium carbonate in the vesicles. This mineral phase appears as aggregates of 20-30-nm nanospheres, consistent with amorphous calcium carbonate. The aggregates finally are introduced into the spicule compartment, where they integrate into the growing spicule.

Calcium as a cardiovascular toxin in CKD-MBD.

PubMed

Moe, Sharon M

2017-07-01

Disordered calcium balance and homeostasis are common in patients with chronic kidney disease. Such alterations are commonly associated with abnormal bone remodeling, directly and indirectly. Similarly, positive calcium balance may also be a factor in the pathogenesis of extra skeletal soft tissue and arterial calcification. Calcium may directly affect cardiac structure and function through direct effects to alter cell signaling due to abnormal intracellular calcium homeostasis 2) extra-skeletal deposition of calcium and phosphate in the myocardium and small cardiac arterioles, 3) inducing cardiomyocyte hypertrophy through calcium and hormone activation of NFAT signaling mechanisms, and 4) increased aorta calcification resulting in chronic increased afterload leading to hypertrophy. Similarly, calcium may alter vascular smooth muscle cell function and affect cell signaling which may predispose to a proliferative phenotype important in arteriosclerosis and arterial calcification. Thus, disorders of calcium balance and homeostasis due to CKD-MBD may play a role in the high cardiovascular burden observed in patients with CKD. Published by Elsevier Inc.

The effect of brushing with nano calcium carbonate and calcium carbonate toothpaste on the surface roughness of nano-ionomer

NASA Astrophysics Data System (ADS)

Anisja, D. H.; Indrani, D. J.; Herda, E.

2017-08-01

Nanotechnology developments in dentistry have resulted in the development of nano-ionomer, a new restorative material. The surface roughness of restorative materials can increase bacteria adhesion and lead to poor oral hygiene. Abrasive agents in toothpaste can alter tooth and restorative material surfaces. The aim of this study is to identify the effect of brushing with nano calcium carbonate, and calcium carbonate toothpaste on surface roughness of nano-ionomer. Eighteen nano-ionomer specimens were brushed with Aquabidest (doubledistilled water), nano calcium carbonate and calcium carbonate toothpaste. Brushing lasted 30 minutes, and the roughness value (Ra) was measured after each 10 minute segment using a surface roughness tester. The data was analyzed using repeated ANOVA and one-way ANOVA test. The value of nano-ionomer surface roughness increased significantly (p<0.05) after 20 minutes of brushing with the nano calcium carbonate toothpaste. Brushing with calcium carbonate toothpaste leaves nano-ionomer surfaces more rugged than brushing with nano calcium carbonate toothpaste.

Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

NASA Technical Reports Server (NTRS)

Simske, S. J.; Luttges, M. W.; Allen, K. A.; Spooner, B. S. (Principal Investigator)

1992-01-01

The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

Cadmium and calcium uptake in the mollusc donax rugosus and effect of a calcium channel blocker

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sidoumou, Z.; Gnassia-Barelli, M.; Romeo, M.

Donax rugosus, a common bivalve mollusc in the coastal waters of Mauritania, has been studied for trace metal concentrations as a function of sampling site (from South of Mauritania to the North of this country) and of season. In this paper, the uptake of cadmium was experimentally studied in the different organs of D. rugosus. Since metals such as cadmium, copper and mercury may alter calcium homeostasis, calcium uptake was also studied in the animals treated with cadmium. Since calcium is taken up through specific channels, it appears that metals inhibit Ca uptake by interacting with these channels in themore » plasma membrane. Cadmium and calcium have very similar atomic radii, thus cadmium may be taken up through the calcium channels, particularly through voltage-dependent channels. The uptake of cadmium and calcium by D. Rugosus was therefore also studied in the presence of the calcium channel blocker verapamil. 13 refs., 3 figs., 1 tab.« less

Regulation of Cellular Calcium in Vestibular Supporting Cells by Otopetrin 1

PubMed Central

Kim, Euysoo; Hyrc, Krzysztof L.; Speck, Judith; Lundberg, Yunxia W.; Salles, Felipe T.; Kachar, Bechara; Goldberg, Mark P.; Warchol, Mark E.

2010-01-01

Otopetrin 1 (OTOP1) is a multitransmembrane domain protein, which is essential for mineralization of otoconia, the calcium carbonate biominerals required for vestibular function, and the normal sensation of gravity. The mechanism driving mineralization of otoconia is poorly understood, but it has been proposed that supporting cells and a mechanism to maintain high concentrations of calcium are critical. Using Otop1 knockout mice and a utricular epithelial organ culture system, we show that OTOP1 is expressed at the apex of supporting cells and functions to increase cytosolic calcium in response to purinergic agonists, such as adenosine 5′-triphosphate (ATP). This is achieved by blocking mobilization of calcium from intracellular stores in an extracellular calcium-dependent manner and by mediating influx of extracellular calcium. These data support a model in which OTOP1 acts as a sensor of the extracellular calcium concentration near supporting cells and responds to ATP in the endolymph to increase intracellular calcium levels during otoconia mineralization. PMID:20554841

Effects of calcium supplements on the quality and acrylamide content of puffed shrimp chips.

PubMed

Chen, Tai-Yuan; Luo, Hsuan-Min; Hsu, Pang-Hung; Sung, Wen-Chieh

2016-01-01

The quality and acrylamide content of deep-fried and microwave-puffed shrimp chips fortified with 0.1%, 0.5%, or 1.0% calcium salts (calcium lactate, calcium carbonate, calcium citrate, or calcium acetate) were investigated. Microwave-puffed shrimp chips contained higher amounts of acrylamide (130.43 ppb) than did deep-fried shrimp chips. The greatest mitigation of acrylamide formation in overfried chips was obtained with 0.1% calcium lactate. All browning indexes of fortified shrimp chips, whether deep-fried or microwave-puffed, were reduced. L* values of microwave-puffed shrimp chips were higher than those of deep-fried shrimp chips, whereas a* and b* values and browning indexes were lower. Color differences (ΔE) between deep-fried puffed shrimp chips fortified with calcium salts and a control sample were higher than 5, and the sensory scores of shrimp chips were significantly decreased by the addition of calcium lactate. Copyright © 2015. Published by Elsevier B.V.

The complex nature of calcium cation interactions with phospholipid bilayers

NASA Astrophysics Data System (ADS)

Melcrová, Adéla; Pokorna, Sarka; Pullanchery, Saranya; Kohagen, Miriam; Jurkiewicz, Piotr; Hof, Martin; Jungwirth, Pavel; Cremer, Paul S.; Cwiklik, Lukasz

2016-12-01

Understanding interactions of calcium with lipid membranes at the molecular level is of great importance in light of their involvement in calcium signaling, association of proteins with cellular membranes, and membrane fusion. We quantify these interactions in detail by employing a combination of spectroscopic methods with atomistic molecular dynamics simulations. Namely, time-resolved fluorescent spectroscopy of lipid vesicles and vibrational sum frequency spectroscopy of lipid monolayers are used to characterize local binding sites of calcium in zwitterionic and anionic model lipid assemblies, while dynamic light scattering and zeta potential measurements are employed for macroscopic characterization of lipid vesicles in calcium-containing environments. To gain additional atomic-level information, the experiments are complemented by molecular simulations that utilize an accurate force field for calcium ions with scaled charges effectively accounting for electronic polarization effects. We demonstrate that lipid membranes have substantial calcium-binding capacity, with several types of binding sites present. Significantly, the binding mode depends on calcium concentration with important implications for calcium buffering, synaptic plasticity, and protein-membrane association.

Spectroscopic investigation of the influence of calcium ion on the structures of casein micelles.

PubMed

Wang, Peng-Jie; Wu, Jian-Ping; Zhang, Hao; Guo, Hui-Yuan; Liu, Hong-Na; Ren, Fa-Zheng

2014-01-01

The effects of calcium ion on the structural properties of casein micelles in the course of heat treatment were synthetically examined by non-structure-invasive spectrometry. The hydrophobicity, reflected by extrinsic fluorescence (ANS fluorescence), was positively correlated with the concentration of the calcium ion, within the range of 0 to 12 mmol x L(-1). Meanwhile, the turbidity and stability of casein micelles also increased with the growth of calcium concentrations. However, opposite results were observed for hydrodynamic diameter and polydispersity index. Compared with the calcium ion, the calcium-chelator (citrate) has an opposite effect on the structural characteristics of casein micelles. Within the calcium concentrations range of 0 to 12 mmol x L(-1), the hydrophobicity, stability and turbidity were negatively correlated with the concentration of the calcium ion, nevertheless, opposite results were observed for hydrodynamic diameter and polydispersity index. All the results indicate that the calcium ion could be used to modify the structures of casein micelles during heat heatment.

The activity of calcium in calcium-metal-fluoride fluxes

NASA Astrophysics Data System (ADS)

Ochifuji, Yuichiro; Tsukihashi, Fumitaka; Sano, Nobuo

1995-08-01

The standard Gibbs energy of reaction Ca (1) + O (mass pct, in Zr) = CaO (s) has been determined as follows by equilibrating molten calcium with solid zirconium in a CaO crucible: Δ G° = -64,300(±700) + 19.8(±3.5) T J/mol (1373 to 1623 K) The activities of calcium in the CaOsatd-Ca- MF2 ( M: Ca, Ba, Mg) and CaOsatd-Ca-NaF systems were measured as a function of calcium composition at high calcium contents at 1473 K on the basis of the standard Gibbs energy. The activities of calcium increase in the order of CaF2, BaF2, and MgF2 at the same calcium fraction of these fluxes. The observed activities are compared with those estimated by using the Temkin model for ionic solutions. Furthermore, the possibility of the removal of tramp elements such as tin, arsenic, antimony, bismuth, and lead from carbon-saturated iron by using calcium-metal-fluoride fluxes is discussed.

Calcium at fertilization and in early development

PubMed Central

Whitaker, Michael

2012-01-01

Fertilization calcium waves are introduced and the evidence from which we can infer general mechanisms of these waves is presented. The two main classes of hypothesis put forward to explain the generation of the fertilization calcium wave are set out and it is concluded that initiation of the fertilization calcium wave can be most generally explained in inverterbrates by a mechanism in which an activating substance enters the egg from the sperm on sperm-egg fusion, activating the egg by stimulating phospholipase C activation through a src family kinase pathway and in mammals by the diffusion of a sperm-specific phospholipase C from sperm to egg on sperm-egg fusion. The fertilization calcium wave is then set into the context of cell cycle control and the mechanism of repetitive calcium spiking in mammalian eggs is investigated. Evidence that calcium signals control cell division in early embryos is reviewed, and it is concluded that calcium signals are essential at all three stages of cell division in early embryos. Evidence that phosphoinositide signalling pathways control the resumption of meiosis during oocyte maturation is considered. It is concluded on balance that the evidence points to a need for phosphoinositide/calcium signalling during resumption of meiosis. Changes to the calcium signalling machinery occur during meiosis to enable the production of a calcium wave in the mature oocyte when it is fertilized; evidence that the shape and structure of the endoplasmic reticulum alters dynamically during maturation and after fertilization is reviewed and the link between ER dynamics and the cytoskeleton is discussed. There is evidence that calcium signalling plays a key part in the development of patterning in early embryos. Morphogenesis in ascidian, frog and zebrafish embryos is briefly described to provide the developmental context in which calcium signals act. Intracellular calcium waves that may play a role in axis formation in ascidian are discussed. Evidence that the Wingless/calcium signalling pathway is a strong ventralizing signal in Xenopus, mediated by phoshoinositide signalling is adumbrated. The central role that calcium channels play in morphogenetic movements during gastrulation and in ectodermal and mesodermal gene expression during late gastrulation is demonstrated. Experiments in zebrafish provide a strong indication that calcium signals are essential for pattern formation and organogenesis. PMID:16371595

The expanded amelogenin polyproline region preferentially binds to apatite versus carbonate and promotes apatite crystal elongation

PubMed Central

Gopinathan, Gokul; Jin, Tianquan; Liu, Min; Li, Steve; Atsawasuwan, Phimon; Galang, Maria-Therese; Allen, Michael; Luan, Xianghong; Diekwisch, Thomas G. H.

2014-01-01

The transition from invertebrate calcium carbonate-based calcite and aragonite exo- and endoskeletons to the calcium phosphate-based vertebrate backbones and jaws composed of microscopic hydroxyapatite crystals is one of the great revolutions in the evolution of terrestrial organisms. To identify potential factors that might have played a role in such a transition, three key domains of the vertebrate tooth enamel protein amelogenin were probed for calcium mineral/protein interactions and their ability to promote calcium phosphate and calcium carbonate crystal growth. Under calcium phosphate crystal growth conditions, only the carboxy-terminus augmented polyproline repeat peptide, but not the N-terminal peptide nor the polyproline repeat peptide alone, promoted the formation of thin and parallel crystallites resembling those of bone and initial enamel. In contrast, under calcium carbonate crystal growth conditions, all three amelogenin-derived polypeptides caused calcium carbonate to form fused crystalline conglomerates. When examined for long-term crystal growth, polyproline repeat peptides of increasing length promoted the growth of shorter calcium carbonate crystals with broader basis, contrary to the positive correlation between polyproline repeat element length and apatite mineralization published earlier. To determine whether the positive correlation between polyproline repeat element length and apatite crystal growth versus the inverse correlation between polyproline repeat length and calcium carbonate crystal growth were related to the binding affinity of the polyproline domain to either apatite or carbonate, a parallel series of calcium carbonate and calcium phosphate/apatite protein binding studies was conducted. These studies demonstrated a remarkable binding affinity between the augmented amelogenin polyproline repeat region and calcium phosphates, and almost no binding to calcium carbonates. In contrast, the amelogenin N-terminus bound to both carbonate and apatite, but preferentially to calcium carbonate. Together, these studies highlight the specific binding affinity of the augmented amelogenin polyproline repeat region to calcium phosphates versus calcium carbonate, and its unique role in the growth of thin apatite crystals as they occur in vertebrate biominerals. Our data suggest that the rise of apatite-based biominerals in vertebrates might have been facilitated by a rapid evolution of specialized polyproline repeat proteins flanked by a charged domain, resulting in apatite crystals with reduced width, increased length, and tailored biomechanical properties. PMID:25426079

Calcium source (image)

MedlinePlus

Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with calcium hydroxide or calcium carbonate. It occurs as a fine white, odorless powder and...

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with calcium hydroxide or calcium carbonate. It occurs as a fine white, odorless powder and...

Seasonal Variations in Mercury's Dayside Calcium Exosphere

NASA Technical Reports Server (NTRS)

Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Merkel, Aimee W.; Vervack, Ronald J., Jr.; Cassidy, Timothy A.; Sarantos, Menelaos

2014-01-01

The Mercury Atmospheric and Surface Composition Spectrometer on the MESSENGER spacecraft has observed calcium emission in Mercury's exosphere on a near-daily basis since March 2011. During MESSENGER's primary and first extended missions (March 2011 - March 2013) the dayside calcium exosphere was measured over eight Mercury years. We have simulated these data with a Monte Carlo model of exospheric source processes to show that (a) there is a persistent source of energetic calcium located in the dawn equatorial region, (b) there is a seasonal dependence in the calcium source rate, and (c) there are no obvious year-to-year variations in the near-surface dayside calcium exosphere. Although the precise mechanism responsible for ejecting the calcium has not yet been determined, the most likely process is the dissociation of Ca-bearing molecules produced in micrometeoroid impact plumes to form energetic, escaping calcium atoms.

The effects of crustacean cardioactive peptide on locust oviducts are calcium-dependent.

PubMed

Donini, Andrew; Lange, Angela B

2002-04-01

The role of calcium as a second messenger in the crustacean cardioactive peptide (CCAP)-induced contractions of the locust oviducts was investigated. Incubation of the oviducts in a calcium-free saline containing, a preferential calcium cation chelator, or an extracellular calcium channel blocker, abolished CCAP-induced contractions, indicating that the effects of CCAP on the oviducts are calcium-dependent. In contrast, sodium free saline did not affect CCAP-induced contractions. Co-application of CCAP to the oviducts with preferential L-type voltage-dependent calcium channel blockers reduced CCAP-induced contractions by 32-54%. Two preferential T-type voltage-dependent calcium channel blockers both inhibited CCAP-induced oviduct contractions although affecting different components of the contractions. Amiloride decreased the tonic component of CCAP-induced contractions by 40-55% and flunarizine dihydrochloride decreased the frequency of CCAP-induced phasic contractions by as much as 65%, without affecting tonus. Flunarizine dihydrochloride did not alter the proctolin-induced contractions of the oviducts. Results suggest that the actions of CCAP are partially mediated by voltage-dependent calcium channels similar to vertebrate L-type and T-type channels. High-potassium saline does not abolish CCAP-induced contractions indicating the presence of receptor-operated calcium channels that mediate the actions of CCAP on the oviducts. The involvement of calcium from intracellular stores in CCAP-induced contractions of the oviducts is likely since, an intracellular calcium antagonist decreased CCAP-induced contractions by 30-35%.

Effect of incorporation of calcium lactate on physico-chemical, textural, and sensory properties of restructured buffalo meat loaves

PubMed Central

Irshad, A.; Sharma, B. D.; Ahmed, S. R.; Talukder, S.; Malav, O. P.; Kumar, Ashish

2016-01-01

Aim: The present study was conducted to develop a functional meat product by fortifying calcium (in the form of calcium lactate) with restructured buffalo meat loaf (RBML). Materials and Methods: Deboned buffalo meat obtained from the carcass of adult female buffalo within 5-6 h of slaughter and stored under frozen condition. Calcium fortified RBML were prepared by replacing the lean buffalo meat with calcium lactate powder at 0%, 1%, 1.25%, and 1.5% level through the pre-standardized procedure. The developed products were evaluated for physico-chemical properties, proximate composition, calcium concentration (mg/100 g), water activity (aw), Lovibond® tintometer color units, texture profile analysis (TPA), and sensory qualities as per-standard procedures. Results: Of the various product quality parameters evaluated, cooking yield (%), product pH, moisture (%), protein (%), fat (%), and water activity (aw) decreases significantly with increasing level of calcium lactate. Calcium content of fortified functional RBMLs was 135.02, 165.73, and 203.85 mg/100 g as compared to 6.48 mg/100 g in control. Most of the sensory scores at 1% and 1.25% levels of calcium lactate in treatment products remained comparable among themselves and control product, with a gradual decline. Conclusions: The present study concluded that 1.25% calcium lactate was the optimum level for the fortification of calcium in RBML without affecting the textural and sensory properties which could meet out 15% of recommended dietary allowance for calcium. PMID:27051201

Effect of incorporation of calcium lactate on physico-chemical, textural, and sensory properties of restructured buffalo meat loaves.

PubMed

Irshad, A; Sharma, B D; Ahmed, S R; Talukder, S; Malav, O P; Kumar, Ashish

2016-02-01

The present study was conducted to develop a functional meat product by fortifying calcium (in the form of calcium lactate) with restructured buffalo meat loaf (RBML). Deboned buffalo meat obtained from the carcass of adult female buffalo within 5-6 h of slaughter and stored under frozen condition. Calcium fortified RBML were prepared by replacing the lean buffalo meat with calcium lactate powder at 0%, 1%, 1.25%, and 1.5% level through the pre-standardized procedure. The developed products were evaluated for physico-chemical properties, proximate composition, calcium concentration (mg/100 g), water activity (aw), Lovibond(®) tintometer color units, texture profile analysis (TPA), and sensory qualities as per-standard procedures. Of the various product quality parameters evaluated, cooking yield (%), product pH, moisture (%), protein (%), fat (%), and water activity (aw) decreases significantly with increasing level of calcium lactate. Calcium content of fortified functional RBMLs was 135.02, 165.73, and 203.85 mg/100 g as compared to 6.48 mg/100 g in control. Most of the sensory scores at 1% and 1.25% levels of calcium lactate in treatment products remained comparable among themselves and control product, with a gradual decline. The present study concluded that 1.25% calcium lactate was the optimum level for the fortification of calcium in RBML without affecting the textural and sensory properties which could meet out 15% of recommended dietary allowance for calcium.

The effect of calcium hydroxide on the antibiotic component of Odontopaste and Ledermix paste.

PubMed

Athanassiadis, M; Jacobsen, N; Nassery, K; Parashos, P

2013-06-01

To investigate the chemical interaction of calcium hydroxide with the antibiotics demeclocycline calcium in Ledermix Paste and clindamycin hydrochloride in Odontopaste. Validated methods were developed to analyse the interaction of calcium hydroxide in two forms, Pulpdent and calcium hydroxide powder, with the two antibiotics. High-performance liquid chromatography (HPLC) was used to analyse the mixed samples of the pastes and calcium hydroxide. The concentration of demeclocycline calcium over 0-, 1-, 18-, 24-, 72-h and 7-day time-points was determined. The concentration of clindamycin hydrochloride over 1-, 6-, 24-, 72-h and 7-day time-points was determined. All tests with HPLC involved testing of the standard in duplicate alongside the samples. Linearity, precision and specificity of the testing procedures and apparatus were validated. Descriptive statistics are provided. The antibiotics in both Odontopaste and Ledermix Paste were affected by the addition of calcium hydroxide. When mixed with calcium hydroxide powder, Odontopaste had a 2% loss of clindamycin hydrochloride over 7 days, but when mixed with Pulpdent, there was a 36% loss over 7 days. Ledermix Paste showed an 80% loss of demeclocycline calcium over 7 days when mixed with calcium hydroxide powder and a 19% loss when mixed with Pulpdent over the 7-day period. The addition of calcium hydroxide to Odontopaste or Ledermix Paste results in reductions of the respective antibiotic over a 7-day time period. © 2012 International Endodontic Journal. Published by Blackwell Publishing Ltd.

Dynamic modulation of spike timing-dependent calcium influx during corticostriatal upstates

PubMed Central

Evans, R. C.; Maniar, Y. M.

2013-01-01

The striatum of the basal ganglia demonstrates distinctive upstate and downstate membrane potential oscillations during slow-wave sleep and under anesthetic. The upstates generate calcium transients in the dendrites, and the amplitude of these calcium transients depends strongly on the timing of the action potential (AP) within the upstate. Calcium is essential for synaptic plasticity in the striatum, and these large calcium transients during the upstates may control which synapses undergo plastic changes. To investigate the mechanisms that underlie the relationship between calcium and AP timing, we have developed a realistic biophysical model of a medium spiny neuron (MSN). We have implemented sophisticated calcium dynamics including calcium diffusion, buffering, and pump extrusion, which accurately replicate published data. Using this model, we found that either the slow inactivation of dendritic sodium channels (NaSI) or the calcium inactivation of voltage-gated calcium channels (CDI) can cause high calcium corresponding to early APs and lower calcium corresponding to later APs. We found that only CDI can account for the experimental observation that sensitivity to AP timing is dependent on NMDA receptors. Additional simulations demonstrated a mechanism by which MSNs can dynamically modulate their sensitivity to AP timing and show that sensitivity to specifically timed pre- and postsynaptic pairings (as in spike timing-dependent plasticity protocols) is altered by the timing of the pairing within the upstate. These findings have implications for synaptic plasticity in vivo during sleep when the upstate-downstate pattern is prominent in the striatum. PMID:23843436

First evidence on phloem transport of nanoscale calcium oxide in groundnut using solution culture technique

NASA Astrophysics Data System (ADS)

Deepa, Manchala; Sudhakar, Palagiri; Nagamadhuri, Kandula Venkata; Balakrishna Reddy, Kota; Giridhara Krishna, Thimmavajjula; Prasad, Tollamadugu Naga Venkata Krishna Vara

2015-06-01

Nanoscale materials, whose size typically falls below 100 nm, exhibit novel chemical, physical and biological properties which are different from their bulk counterparts. In the present investigation, we demonstrated that nanoscale calcium oxide particles (n-CaO) could transport through phloem tissue of groundnut unlike the corresponding bulk materials. n-CaO particles are prepared using sol-gel method. The size of the as prepared n-CaO measured (69.9 nm) using transmission electron microscopic technique (TEM). Results of the hydroponics experiment using solution culture technique revealed that foliar application of n-CaO at different concentrations (10, 50, 100, 500, 1,000 ppm) on groundnut plants confirmed the entry of calcium into leaves and stems through phloem compared to bulk source of calcium sprayed (CaO and CaNO3). After spraying of n-CaO, calcium content in roots, shoots and leaves significantly increased. Based on visual scoring of calcium deficiency correction and calcium content in plant parts, we may establish the fact that nanoscale calcium oxide particles (size 69.9 nm) could move through phloem tissue in groundnut. This is the first report on phloem transport of nanoscale calcium oxide particles in plants and this result points to the use of nanoscale calcium oxide particles as calcium source to the plants through foliar application, agricultural crops in particular, as bulk calcium application through foliar nutrition is restricted due to its non-mobility in phloem.

Discrimination of clinically significant calcium salts using MARS spectral CT

NASA Astrophysics Data System (ADS)

Kirkbride, T. E.; Raja, A.; Mueller, K.; Bateman, C. J.; Becce, F.; Anderson, N.

2017-03-01

Calcium compounds within tissues are usually a sign of pathology, and calcium crystal type is often a pointer to the diagnosis. There are clinical advantages in being able to determine the quantity and type of calcifications non-invasively in cardiovascular, genitourinary and musculoskeletal disorders, and treatment differs depending on the crystal type and quantity. The problem arises when trying to distinguish between different calcium compounds within the same image due to their similar attenuation properties. There are spectroscopic differences between calcium salts at very low energies. As calcium oxalate and calcium hydroxyapatite can co-exist in breast and musculoskeletal pathologies of the breast, we wished to determine whether Spectral CT could distinguish between them in the same image at clinical X-ray energy ranges. Energy thresholds of 15, 22, 29 and 36keV and tube voltages of 50, 80 and 110kVp were chosen, and images were analysed to determine the percentage difference in the attenuation coefficients of calcium hydroxyapatite samples at concentrations of 54.3, 211.7, 808.5 and 1169.3mg/ml, and calcium oxalate at a concentration of 2000 mg/ml. The two lower concentrations of calcium hydroxyapatite were distinguishable from calcium oxalate at all energies and all tube voltages, whereas the ability to discriminate oxalate from hydroxyapatite at higher concentrations was dependent on the threshold energy but only mildly dependent on the tube voltage used. Spectral CT shows promise for distinguishing clinically important calcium salts.

Flow perfusion culture of MC3T3-E1 osteogenic cells on gradient calcium polyphosphate scaffolds with different pore sizes.

PubMed

Chen, Liang; Song, Wei; Markel, David C; Shi, Tong; Muzik, Otto; Matthew, Howard; Ren, Weiping

2016-02-01

Calcium polyphosphate is a biodegradable bone substitute. It remains a challenge to prepare porous calcium polyphosphate with desired gradient porous structures. In this study, a modified one-step gravity sintering method was used to prepare calcium polyphosphate scaffolds with desired-gradient-pore-size distribution. The differences of porous structure, mechanical strength, and degradation rate between gradient and homogenous calcium polyphosphate scaffolds were evaluated by micro-computed tomography, scanning electron microscopy, and mechanical testing. Preosteoblastic MC3T3-E1 cells were seeded onto gradient and homogenous calcium polyphosphate scaffolds and cultured in a flow perfusion bioreactor. The distribution, proliferation, and differentiation of the MC3T3-E1 cells were compared to that of homogenous calcium polyphosphate scaffolds. Though no significant difference of cell proliferation was found between the gradient and the homogenous calcium polyphosphate scaffolds, a much higher cell differentiation and mineralization were observed in the gradient calcium polyphosphate scaffolds than that of the homogenous calcium polyphosphate scaffolds, as manifested by increased alkaline phosphatase activity (p < 0.05). The improved distribution and differentiation of cultured cells within gradient scaffolds were further supported by both (18)F-fluorine micro-positron emission tomography scanning and in vitro tetracycline labeling. We conclude that the calcium polyphosphate scaffold with gradient pore sizes enhances osteogenic cell differentiation as well as mineralization. The in vivo performance of gradient calcium polyphosphate scaffolds warrants further investigation in animal bone defect models. © The Author(s) 2015.

Testing Urey's carbonate-silicate cycle using the calcium isotopic composition of sedimentary carbonates

NASA Astrophysics Data System (ADS)

Blättler, Clara L.; Higgins, John A.

2017-12-01

Carbonate minerals constitute a major component of the sedimentary geological record and an archive of a fraction of the carbon and calcium cycled through the Earth's surface reservoirs for over three billion years. For calcium, carbonate minerals constitute the ultimate sink for almost all calcium liberated during continental and submarine weathering of silicate minerals. This study presents >500 stable isotope ratios of calcium in Precambrian carbonate sediments, both limestones and dolomites, in an attempt to characterize the isotope mass balance of the sedimentary carbonate reservoir through time. The mean of the dataset is indistinguishable from estimates of the calcium isotope ratio of bulk silicate Earth, consistent with the Urey cycle being the dominant mechanism exchanging calcium among surface reservoirs. The variability in bulk sediment calcium isotope ratios within each geological unit does not reflect changes in the global calcium cycle, but rather highlights the importance of local mineralogical and/or diagenetic effects in the carbonate record. This dataset demonstrates the potential for calcium isotope ratios to help assess these local effects, such as the former presence of aragonite, even in rocks with a history of neomorphism and recrystallization. Additionally, 29 calcium isotope measurements are presented from ODP (Ocean Drilling Program) Site 801 that contribute to the characterization of altered oceanic crust as an additional sink for calcium, and whose distinct isotopic signature places a limit on the importance of this subduction flux over Earth history.

Bell-shaped calcium-response curves of lns(l,4,5)P3- and calcium-gated channels from endoplasmic reticulum of cerebellum

NASA Astrophysics Data System (ADS)

Bezprozvanny, Llya; Watras, James; Ehrlich, Barbara E.

1991-06-01

RELEASE of calcium from intracellular stores occurs by two pathways, an inositol 1,4,5-trisphosphate (InsP3)-gated channel1-3 and a calcium-gated channel (ryanodine receptor)4-6. Using specific antibodies, both receptors were found in Purkinje cells of cerebellum7,8. We have now compared the functional properties of the channels corresponding to the two receptors by incorporating endoplasmic reticulum vesicles from canine cerebellum into planar bilayers. InsP3-gated channels were observed most frequently. Another channel type was activated by adenine nucleotides or caffeine, inhibited by ruthenium red, and modified by ryanodine, characteristics of the ryanodine receptor/channel6. The open probability of both channel types displayed a bell-shaped curve for dependence on calcium. For the InsP3-gated channel, the maximum probability of opening occurred at 0.2 µM free calcium, with sharp decreases on either side of the maximum. Maximum activity for the ryanodine receptor/channel was maintained between 1 and 100 µM calcium. Thus, within the physiological range of cytoplasmic calcium, the InsP3-gated channel itself allows positive feed-back and then negative feedback for calcium release, whereas the ryanodine receptor/channel behaves solely as a calcium-activated channel. The existence in the same cell of two channels with different responses to calcium and different ligand sensitivities provides a basis for complex patterns of intracellular calcium regulation.

Effects of calcium and vitamin D supplementation on blood pressure and serum lipids and carotenoids: a randomized, double-blind, placebo-controlled, clinical trial.

PubMed

Chai, Weiwen; Cooney, Robert V; Franke, Adrian A; Bostick, Roberd M

2013-09-01

To estimate the effects of calcium or vitamin D supplementation or a combination of both on blood pressure and serum lipid and carotenoid levels. Ninety-two colorectal adenoma patients were randomized in a pilot, double-blind, placebo-controlled clinical trial of supplemental vitamin D3 800 IU and elemental calcium 2.0 g (as calcium carbonate) alone or in combination in divided doses twice daily with meals over 6 months. Relative to placebo, mean serum triglycerides decreased 30% (P = .10) and 32% (P = .10) in the calcium and calcium plus vitamin D3 treatment groups, respectively. When the two calcium intervention groups were pooled and compared with the pooled noncalcium groups, the estimated supplemental calcium treatment effects were statistically significant for triglycerides (P = .04). Similar but nonstatistically significant decreases (5%-7%) were observed for serum total cholesterol levels. Mean systolic blood pressure increased 6% (P = .08) in the calcium group; otherwise, there were no appreciable changes in systolic or diastolic blood pressures in any active treatment group. Mean serum total carotenoid levels decreased 14% (P = .07) in the calcium and 9% (P = .10) in the calcium plus vitamin D3 groups. Our results suggest that supplemental calcium alone or combined with vitamin D3 but not vitamin D3 alone may reduce serum lipids and lipophilic micronutrients. Copyright © 2013 Elsevier Inc. All rights reserved.

Validation of a short food frequency questionnaire to assess calcium intake in children aged 3 to 6 years.

PubMed

Taylor, R W; Goulding, A

1998-06-01

To assess the validity of a short calcium food frequency questionnaire (FFQ) for use in young children. Calcium intake from an estimated 4 d diet record (4DDR) was compared with the calcium intake from a 35 item FFQ specifically designed to assess habitual calcium intake and previously validated for adult women. Forty-one girls and 26 boys aged 3-6 y recruited by advertisement for studies of nutrition and bone health. Mean (s.d.) calcium intakes were 798 mg (271) and 942 mg (419) for the 4DDR and FFQ respectively, (r = 0.52). Mean difference (s.d. of difference) in calcium intake between the two methods was 144 mg (355), showing that the FFQ may estimate calcium intakes 565 mg below to 854 mg above diet record values. 84% of subjects when classified by the 4DDR fell into the same or adjacent quartiles when classified by the FFQ. Only two subjects were classified in extreme quartiles for the two methods. The FFQ correctly identified 68% of children with recorded intakes less than 800 mg. The short calcium FFQ tended to overestimate actual calcium intakes in young children, and would not be appropriate for determining calcium intake of individuals. However, the FFQ demonstrated good ability to classify subjects into extremes of calcium intake. Moreover, the predictive value of the FFQ in identifying children with intakes below the current recommended intake of 800 mg was reasonably high (79%).

Calcium Isotope Systematics During Development of the Domestic Chicken (Gallus gallus)

NASA Astrophysics Data System (ADS)

Wheatley, P. V.

2003-12-01

Calcium isotope distributions have been recognized as showing systematic and predictable fractionation in nature. However, most of the observed calcium isotope fractionation to date is due to biological processes. The presence of abundant amounts of calcium in mineralized tissues makes the isotopic system of calcium particularly valuable in biological and paleobiological questions involving biomineralization. In order to apply calcium isotope systematics to paleobiological questions the changes in the calcium isotope signatures of mineralized tissue in modern animals should be studied. My study observed the domestic chicken (Gallus gallus) through embryologic ontogeny. This was accomplished by obtaining fertilized eggs staged in a growth series from day 12 to day 20. The eggs were dissected and shell, embryonic bone, albumen, and yolk were analyzed in order to characterize the calcium isotopic composition of the individual components over the course of the growth series. Several systematic changes in the isotopic signatures of various tissues were observed during the course of the development of the embryos. In general, mineralization in biological systems preferentially partitions the lighter isotopes of calcium into hard parts. As a result of this fractionation during mineralization, partitioning of light isotopes of calcium into the mineralized tissues may result in residual tissues being enriched in the heavier isotopes as ontogeny progresses. Better understanding of the behavior of calcium in modern biological systems will improve its application to fossils and expand the number of paleobiological and evolutionary questions that can be addressed using calcium isotopic data.

Air bubble contact with endothelial cells in vitro induces calcium influx and IP3-dependent release of calcium stores

PubMed Central

Sobolewski, Peter; Kandel, Judith; Klinger, Alexandra L.

2011-01-01

Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has demonstrated that contact between air microbubbles and endothelial cells causes a rapid intracellular calcium transient and can lead to cell death. Here we examined the mechanism responsible for the calcium rise. Single air microbubbles (50–150 μm), trapped at the tip of a micropipette, were micromanipulated into contact with individual human umbilical vein endothelial cells (HUVECs) loaded with Fluo-4 (a fluorescent calcium indicator). Changes in intracellular calcium were then recorded via epifluorescence microscopy. First, we confirmed that HUVECs rapidly respond to air bubble contact with a calcium transient. Next, we examined the involvement of extracellular calcium influx by conducting experiments in low calcium buffer, which markedly attenuated the response, or by pretreating cells with stretch-activated channel blockers (gadolinium chloride or ruthenium red), which abolished the response. Finally, we tested the role of intracellular calcium release by pretreating cells with an inositol 1,4,5-trisphosphate (IP3) receptor blocker (xestospongin C) or phospholipase C inhibitor (neomycin sulfate), which eliminated the response in 64% and 67% of cases, respectively. Collectively, our results lead us to conclude that air bubble contact with endothelial cells causes an influx of calcium through a stretch-activated channel, such as a transient receptor potential vanilloid family member, triggering the release of calcium from intracellular stores via the IP3 pathway. PMID:21633077

Calmodulin Activation by Calcium Transients in the Postsynaptic Density of Dendritic Spines

PubMed Central

Keller, Daniel X.; Franks, Kevin M.; Bartol, Thomas M.; Sejnowski, Terrence J.

2008-01-01

The entry of calcium into dendritic spines can trigger a sequence of biochemical reactions that begins with the activation of calmodulin (CaM) and ends with long-term changes to synaptic strengths. The degree of activation of CaM can depend on highly local elevations in the concentration of calcium and the duration of transient increases in calcium concentration. Accurate measurement of these local changes in calcium is difficult because the spaces are so small and the numbers of molecules are so low. We have therefore developed a Monte Carlo model of intracellular calcium dynamics within the spine that included calcium binding proteins, calcium transporters and ion channels activated by voltage and glutamate binding. The model reproduced optical recordings using calcium indicator dyes and showed that without the dye the free intracellular calcium concentration transient was much higher than predicted from the fluorescent signal. Excitatory postsynaptic potentials induced large, long-lasting calcium gradients across the postsynaptic density, which activated CaM. When glutamate was released at the synapse 10 ms before an action potential occurred, simulating activity patterns that strengthen hippocampal synapses, the calcium gradient and activation of CaM in the postsynaptic density were much greater than when the order was reversed, a condition that decreases synaptic strengths, suggesting a possible mechanism underlying the induction of long-term changes in synaptic strength. The spatial and temporal mechanisms for selectivity in CaM activation demonstrated here could be used in other signaling pathways. PMID:18446197

Randomized crossover study comparing the phosphate-binding efficacy of calcium ketoglutarate versus calcium carbonate in patients on chronic hemodialysis.

PubMed

Bro, S; Rasmussen, R A; Handberg, J; Olgaard, K; Feldt-Rasmussen, B

1998-02-01

The objective of the study was to evaluate the phosphate-binding efficacy, side effects, and cost of therapy of calcium ketoglutarate granulate as compared with calcium carbonate tablets in patients on chronic hemodialysis. The study design used was a randomized, crossover open trial, and the main outcome measurements were plasma ionized calcium levels, plasma phosphate levels, plasma intact parathyroid hormone (PTH) levels, requirements for supplemental aluminum-aminoacetate therapy, patient tolerance, and cost of therapy. Nineteen patients on chronic hemodialysis were treated with a dialysate calcium concentration of 1.25 mmol/L and a fixed alfacalcidol dose for at least 2 months. All had previously tolerated therapy with calcium carbonate. Of the 19 patients included, 10 completed both treatment arms. After 12 weeks of therapy, the mean (+/-SEM) plasma ionized calcium level was significantly lower in the ketoglutarate arm compared with the calcium carbonate arm (4.8+/-0.1 mg/dL v 5.2+/-0.1 mg/dL; P = 0.004), whereas the mean plasma phosphate (4.5+/-0.3 mg/dL v 5.1+/-0.1 mg/dL) and PTH levels (266+/-125 pg/mL v 301+/-148 pg/mL) did not differ significantly between the two treatment arms. Supplemental aluminum-aminoacetate was not required during calcium ketoglutarate treatment, while two patients needed this supplement when treated with calcium carbonate. Five of 17 (29%) patients were withdrawn from calcium ketoglutarate therapy within 1 to 2 weeks due to intolerance (anorexia, vomiting, diarrhea, general uneasiness), whereas the remaining 12 patients did not experience any side effects at all. The five patients with calcium ketoglutarate intolerance all had pre-existing gastrointestinal symptoms; four of them had received treatment with cimetidine or omeprazol before inclusion into the study. Calculations based on median doses after 12 weeks showed that the cost of the therapy in Denmark was 10 times higher for calcium ketoglutarate compared with calcium carbonate (US$6.00/d v US$0.65/d). Calcium ketoglutarate may be an effective and safe alternative to treatment with aluminum-containing phosphate binders in patients on hemodialysis who are intolerant of calcium carbonate or acetate because of hypercalcemia. However, care must be exercised when dealing with patients with pre-existing gastrointestinal discomfort. Due to the high cost of the therapy, calcium ketoglutarate should be used only for selected patients.

Nitric oxide augments voltage-activated calcium currents of crustacea (Idotea baltica) skeletal muscle.

PubMed

Erxleben, C; Hermann, A

2001-03-16

Invertebrate skeletal muscle contraction is regulated by calcium influx through voltage-dependent calcium channels in the sarcolemmal membrane. In present study we investigated the effects of nitric oxide (NO) donors on calcium currents of single skeletal muscle fibres from the marine isopod, Idotea baltica, using two-electrode voltage clamp recording techniques. The NO donors, S-nitrosocysteine, S-nitroso-N-acetyl-penicillamine or hydroxylamine reversibly increased calcium inward currents in a time dependent manner. The increase of the current was prevented by methylene blue. Our experiments suggest that NO increases calcium inward currents. NO, by acting on calcium ion channels in the sarcolemmal membrane, therefore, may directly be involved in the modulation of muscle contraction.

Induced calcium carbonate precipitation using Bacillus species.

PubMed

Seifan, Mostafa; Samani, Ali Khajeh; Berenjian, Aydin

2016-12-01

Microbially induced calcium carbonate precipitation is an emerging process for the production of self-healing concrete. This study was aimed to investigate the effects and optimum conditions on calcium carbonate biosynthesis. Bacillus licheniformis, Bacillus sphaericus, yeast extract, urea, calcium chloride and aeration were found to be the most significant factors affecting the biomineralization of calcium carbonate. It was noticed that the morphology of microbial calcium carbonate was mainly affected by the genera of bacteria (cell surface properties), the viscosity of the media and the type of electron acceptors (Ca 2+ ). The maximum calcium carbonate concentration of 33.78 g/L was achieved at the optimum conditions This value is the highest concentration reported in the literature.

21 CFR 184.1229 - Calcium stearate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium stearate. 184.1229 Section 184.1229 Food... GRAS § 184.1229 Calcium stearate. (a) Calcium stearate (Ca(C17H35COO)2, CAS Reg. No. 1529-23-0) is the calcium salt of stearic acid derived from edible sources. It is prepared as a white precipitate by mixing...

21 CFR 184.1193 - Calcium chloride.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium chloride. 184.1193 Section 184.1193 Food... Specific Substances Affirmed as GRAS § 184.1193 Calcium chloride. (a) Calcium chloride (CaCl2·2H2O, CAS Reg. No. 10035-04-8) or anhydrous calcium chloride (CaCl2, CAS Reg. No. 10043-52-4) may be commercially...

21 CFR 184.1193 - Calcium chloride.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium chloride. 184.1193 Section 184.1193 Food... Specific Substances Affirmed as GRAS § 184.1193 Calcium chloride. (a) Calcium chloride (CaCl2·2H2O, CAS Reg. No. 10035-04-8) or anhydrous calcium chloride (CaCl2, CAS Reg. No. 10043-52-4) may be commercially...

21 CFR 184.1185 - Calcium acetate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium acetate. 184.1185 Section 184.1185 Food... Specific Substances Affirmed as GRAS § 184.1185 Calcium acetate. (a) Calcium acetate (Ca (C2H3O2)2, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It...

21 CFR 184.1193 - Calcium chloride.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium chloride. 184.1193 Section 184.1193 Food... GRAS § 184.1193 Calcium chloride. (a) Calcium chloride (CaCl2·2H2O, CAS Reg. No. 10035-04-8) or anhydrous calcium chloride (CaCl2, CAS Reg. No. 10043-52-4) may be commercially obtained as a byproduct in...

21 CFR 184.1185 - Calcium acetate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium acetate. 184.1185 Section 184.1185 Food... GRAS § 184.1185 Calcium acetate. (a) Calcium acetate (Ca (C2H3O2)2, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the...

21 CFR 184.1185 - Calcium acetate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium acetate. 184.1185 Section 184.1185 Food... Specific Substances Affirmed as GRAS § 184.1185 Calcium acetate. (a) Calcium acetate (Ca (C2H3O2)2, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It...

Calcium release-dependent inactivation precedes formation of the tubular system in developing rat cardiac myocytes.

PubMed

Macková, Katarina; Zahradníková, Alexandra; Hoťka, Matej; Hoffmannová, Barbora; Zahradník, Ivan; Zahradníková, Alexandra

2017-12-01

Developing cardiac myocytes undergo substantial structural and functional changes transforming the mechanism of excitation-contraction coupling from the embryonic form, based on calcium influx through sarcolemmal DHPR calcium channels, to the adult form, relying on local calcium release through RYR calcium channels of sarcoplasmic reticulum stimulated by calcium influx. We characterized day-by-day the postnatal development of the structure of sarcolemma, using techniques of confocal fluorescence microscopy, and the development of the calcium current, measured by the whole-cell patch-clamp in isolated rat ventricular myocytes. We characterized the appearance and expansion of the t-tubule system and compared it with the appearance and progress of the calcium current inactivation induced by the release of calcium ions from sarcoplasmic reticulum as structural and functional measures of direct DHPR-RYR interaction. The release-dependent inactivation of calcium current preceded the development of the t-tubular system by several days, indicating formation of the first DHPR-RYR couplons at the surface sarcolemma and their later spreading close to contractile myofibrils with the growing t-tubules. Large variability of both of the measured parameters among individual myocytes indicates uneven maturation of myocytes within the growing myocardium.

Calcium pump kinetics determined in single erythrocyte ghosts by microphotolysis and confocal imaging.

PubMed

Kubitscheck, U; Pratsch, L; Passow, H; Peters, R

1995-07-01

The activity of the plasma membrane calcium pump was measured in single cells. Human red blood cell ghosts were loaded with a fluorescent calcium indicator and either caged calcium and ATP (protocol A) or caged ATP and calcium (protocol B). In a suitably modified laser scanning microscope either calcium or ATP were released by a short UV light pulse. The time-dependent fluorescence intensity of the calcium indicator was then followed in single ghosts by repetitive confocal imaging. The fluorescence intensity was converted into calcium concentration, which in turn was used to derive the kinetic parameters of the calcium pump, the Michaelis-Menten constant Km, and the maximal transport rate vmax. Km and vmax values derived in this manner were 24 +/- 14 microM and 1.0 +/- 0.6 microM/(ghost s) for protocol A, and 4 +/- 3 microM and 1.0 +/- 0.6 microM/(ghost s) for protocol B, respectively. The difference between A and B is presumably caused by calmodulin, which is inactive in the experiments with protocol A. The possibilities to extend the new method to living nucleus-containing cells transiently transfected with mutants of the plasma membrane calcium pump are discussed.

Structural evidence that botulinum toxin blocks neuromuscular transmission by impairing the calcium influx that normally accompanies nerve depolarization

PubMed Central

1981-01-01

Taking advantage of the fact that nerve terminal mitochondria swell and sequester calcium during repetitive nerve stimulation, we here confirm that this change is caused by calcium influx into the nerve and use this fact to show that botulinum toxin abolishes such calcium influx. The optimal paradigm for producing the mitochondrial changes in normal nerves worked out to be 5 min of stimulation at 25 Hz in frog Ringer's solution containing five time more calcium than normal. Applying this same stimulation paradigm to botulinum-intoxicated nerves produced no mitochondrial changes at all. Only when intoxicated nerves were stimulated in 4-aminopyridine (which grossly exaggerates calcium currents in normal nerves) or when they were soaked in black widow spider venom (which is a nerve-specific calcium ionophore) could nerve mitochondria be induced to swell and accumulate calcium. These results indicate that nerve mitochondria are not damaged directly by the toxin and point instead to a primary inhibition of the normal depolarization- evoked calcium currents that accompany nerve activity. Because these currents normally provide the calcium that triggers transmitter secretion from the nerve, this demonstration of their inhibition helps to explain how botulinum toxin paralyzes. PMID:6259176

Building better bones in childhood: a randomized controlled study to test the efficacy of a dietary intervention program to increase calcium intake.

PubMed

Weber, D R; Stark, L J; Ittenbach, R F; Stallings, V A; Zemel, B S

2017-06-01

Many children do not consume the recommended daily allowance of calcium. Inadequate calcium intake in childhood may limit bone accrual. The objective of this study was to determine if a behavioral modification and nutritional education (BM-NE) intervention improved dietary calcium intake and bone accrual in children. 139 (86 female) healthy children, 7-10 years of age, were enrolled in this randomized controlled trial conducted over 36 months. Participants randomized to the BM-NE intervention attended five sessions over a 6-week period designed to increase calcium intake to 1500 mg/day. Participants randomized to the usual care (UC) group received a single nutritional counseling session. The Calcium Counts Food Frequency Questionnaire was used to assess calcium intake; dual energy X-ray absorptiometry was used to assess areal bone mineral density (aBMD) and bone mineral content (BMC). Longitudinal mixed effects models were used to assess for an effect of the intervention on calcium intake, BMC and aBMD. BM-NE participants had greater increases in calcium intake that persisted for 12 months following the intervention compared with UC. The intervention had no effect on BMC or aBMD accrual. Secondary analyses found a negative association between calcium intake and adiposity such that greater calcium intake was associated with lesser gains in body mass index and fat mass index. A family-centered BM-NE intervention program in healthy children was successful in increasing calcium intake for up to 12 months but had no effect on bone accrual. A beneficial relationship between calcium intake and adiposity was observed and warrants future study.

Interactions between calcium and phosphorus in the regulation of the production of fibroblast growth factor 23 in vivo

PubMed Central

Quinn, Stephen J.; Thomsen, Alex R. B.; Pang, Jian L.; Kantham, Lakshmi; Bräuner-Osborne, Hans; Pollak, Martin; Goltzman, David

2013-01-01

Calcium and phosphorus homeostasis are highly interrelated and share common regulatory hormones, including FGF23. However, little is known about calcium's role in the regulation of FGF23. We sought to investigate the regulatory roles of calcium and phosphorus in FGF23 production using genetic mouse models with targeted inactivation of PTH (PTH KO) or both PTH and the calcium-sensing receptor (CaSR; PTH-CaSR DKO). In wild-type, PTH KO, and PTH-CaSR DKO mice, elevation of either serum calcium or phosphorus by intraperitoneal injection increased serum FGF23 levels. In PTH KO and PTH-CaSR DKO mice, however, increases in serum phosphorus by dietary manipulation were accompanied by severe hypocalcemia, which appeared to blunt stimulation of FGF23 release. Increases in dietary phosphorus in PTH-CaSR DKO mice markedly decreased serum 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] despite no change in FGF23, suggesting direct regulation of 1,25(OH)2D3 synthesis by serum phosphorus. Calcium-mediated increases in serum FGF23 required a threshold level of serum phosphorus of about 5 mg/dl. Analogously, phosphorus-elicited increases in FGF23 were markedly blunted if serum calcium was less than 8 mg/dl. The best correlation between calcium and phosphorus and serum FGF23 was found between FGF23 and the calcium × phosphorus product. Since calcium stimulated FGF23 production in the PTH-CaSR DKO mice, this effect cannot be mediated by the full-length CaSR. Thus the regulation of FGF23 by both calcium and phosphorus appears to be fundamentally important in coordinating the serum levels of both mineral ions and ensuring that the calcium × phosphorus product remains within a physiological range. PMID:23233539

Calcium/Vitamin D Supplementation and Coronary Artery Calcification

PubMed Central

Manson, JoAnn E.; Allison, Matthew A.; Carr, J. Jeffrey; Langer, Robert D.; Cochrane, Barbara B.; Hendrix, Susan L.; Hsia, Judith; Hunt, Julie R.; Lewis, Cora E.; Margolis, Karen L.; Robinson, Jennifer G.; Rodabough, Rebecca J.; Thomas, Asha M.

2010-01-01

Objectives Coronary artery calcified plaque is a marker for atheromatous plaque burden and predicts future risk of cardiovascular events. The relationship between calcium plus vitamin D supplementation and coronary artery calcium (CAC) has not been previously assessed in a randomized trial setting. We compared coronary artery calcium scores among women randomized to calcium/vitamin D supplementation versus placebo following trial completion. Methods In an ancillary substudy of women randomized to calcium carbonate (1000 mg of elemental calcium daily) plus vitamin D3 (400 IU daily) versus placebo, nested within the Women’s Health Initiative trial of estrogen among women with hysterectomy, we measured CAC with cardiac computed tomography in 754 women aged 50–59 years at randomization. Imaging for CAC was performed at 28 of 40 centers following a mean of 7 years of treatment and scans were read centrally. Coronary artery calcium scores were measured by a central reading center with masking to randomization assignments. Results Post-trial CAC measurements were similar in women randomized to calcium/vitamin D supplementation (calcium/D) and those receiving placebo. The mean CAC score was 91.6 for calcium/D and 100.5 for placebo (rank test p-value=0.74). After adjustment for coronary risk factors, multivariate odds ratios for increasing CAC score cutpoints (CAC >0, ≥10, and ≥100) for calcium/D vs placebo were 0.92 (95% confidence interval, 0.64–1.34), 1.29 (0.88–1.87), and 0.90 (0.56–1.44), respectively. Corresponding odds ratios among women with >50% adherence to study pills and for higher levels of CAC (>300), were similar. Conclusions Treatment with moderate doses of calcium plus vitamin D3 did not appear to alter coronary artery calcified plaque burden among postmenopausal women. PMID:20551849

Calcium Imaging of AM Dyes Following Prolonged Incubation in Acute Neuronal Tissue

PubMed Central

Morley, John W.; Tapson, Jonathan; Breen, Paul P.; van Schaik, André

2016-01-01

Calcium-imaging is a sensitive method for monitoring calcium dynamics during neuronal activity. As intracellular calcium concentration is correlated to physiological and pathophysiological activity of neurons, calcium imaging with fluorescent indicators is one of the most commonly used techniques in neuroscience today. Current methodologies for loading calcium dyes into the tissue require prolonged incubation time (45–150 min), in addition to dissection and recovery time after the slicing procedure. This prolonged incubation curtails experimental time, as tissue is typically maintained for 6–8 hours after slicing. Using a recently introduced recovery chamber that extends the viability of acute brain slices to more than 24 hours, we tested the effectiveness of calcium AM staining following long incubation periods post cell loading and its impact on the functional properties of calcium signals in acute brain slices and wholemount retinae. We show that calcium dyes remain within cells and are fully functional >24 hours after loading. Moreover, the calcium dynamics recorded >24 hrs were similar to the calcium signals recorded in fresh tissue that was incubated for <4 hrs. These results indicate that long exposure of calcium AM dyes to the intracellular cytoplasm did not alter the intracellular calcium concentration, the functional range of the dye or viability of the neurons. This data extends our previous work showing that a custom recovery chamber can extend the viability of neuronal tissue, and reliable data for both electrophysiology and imaging can be obtained >24hrs after dissection. These methods will not only extend experimental time for those using acute neuronal tissue, but also may reduce the number of animals required to complete experimental goals. PMID:27183102

Calcium ion binding properties of Medicago truncatula calcium/calmodulin-dependent protein kinase.

PubMed

Swainsbury, David J K; Zhou, Liang; Oldroyd, Giles E D; Bornemann, Stephen

2012-09-04

A calcium/calmodulin-dependent protein kinase (CCaMK) is essential in the interpretation of calcium oscillations in plant root cells for the establishment of symbiotic relationships with rhizobia and mycorrhizal fungi. Some of its properties have been studied in detail, but its calcium ion binding properties and subsequent conformational change have not. A biophysical approach was taken with constructs comprising either the visinin-like domain of Medicago truncatula CCaMK, which contains EF-hand motifs, or this domain together with the autoinhibitory domain. The visinin-like domain binds three calcium ions, leading to a conformational change involving the exposure of hydrophobic surfaces and a change in tertiary but not net secondary or quaternary structure. The affinity for calcium ions of visinin-like domain EF-hands 1 and 2 (K(d) = 200 ± 50 nM) was appropriate for the interpretation of calcium oscillations (~125-850 nM), while that of EF-hand 3 (K(d) ≤ 20 nM) implied occupancy at basal calcium ion levels. Calcium dissociation rate constants were determined for the visinin-like domain of CCaMK, M. truncatula calmodulin 1, and the complex between these two proteins (the slowest of which was 0.123 ± 0.002 s(-1)), suggesting the corresponding calcium association rate constants were at or near the diffusion-limited rate. In addition, the dissociation of calmodulin from the protein complex was shown to be on the same time scale as the dissociation of calcium ions. These observations suggest that the formation and dissociation of the complex between calmodulin and CCaMK would substantially mirror calcium oscillations, which typically have a 90 s periodicity.

Calcium intake trends and health consequences from childhood through adulthood.

PubMed

Nicklas, Theresa A

2003-10-01

Issues involving low calcium intake and dairy product consumption are currently the focus of much debate and discussion at both the scientific and lay community levels. In this review, we examine the following major areas of interest: (1). the role of calcium intake and dairy product consumption in chronic diseases, (2). nutritional qualities of milk and other dairy products, (3). trends in calcium intake and dairy product consumption, (4). current status of calcium intakes and dairy product consumption in children, (5). tracking of calcium intake and diary product consumption, (6). the impact of school meal participation on calcium intake and dairy product consumption, (7). concerns related to calcium-fortified foods and beverages and (8). factors influencing children's milk consumption. To date, the findings indicate that calcium intake and dairy product consumption have beneficial roles in a variety of chronic diseases; dairy products provide an abundant source of vitamins and minerals; calcium intakes of children have increased over time, yet intakes are not meeting the current adequate intake (AI) calcium recommendations; dairy consumption has decreased, and soft drink consumption and, possibly, consumption of calcium-fortified products have increased; consumption of dairy products have a positive nutritional impact on diets of children, particularly from school meals, and there are many factors which influence children's milk consumption, all of which need to be considered in our efforts to promote adequate calcium intakes by children. Based on this review, areas that need immediate attention and future research imperatives are summarized in an effort to further our understanding on what we already know and what we need to know to promote healthier eating habits early in life.

Presynaptic strontium dynamics and synaptic transmission.

PubMed Central

Xu-Friedman, M A; Regehr, W G

1999-01-01

Strontium can replace calcium in triggering neurotransmitter release, although peak release is reduced and the duration of release is prolonged. Strontium has therefore become useful in probing release, but its mechanism of action is not well understood. Here we study the action of strontium at the granule cell to Purkinje cell synapse in mouse cerebellar slices. Presynaptic residual strontium levels were monitored with fluorescent indicators, which all responded to strontium (fura-2, calcium orange, fura-2FF, magnesium green, and mag-fura-5). When calcium was replaced by equimolar concentrations of strontium in the external bath, strontium and calcium both entered presynaptic terminals. Contaminating calcium was eliminated by including EGTA in the extracellular bath, or by loading parallel fibers with EGTA, enabling the actions of strontium to be studied in isolation. After a single stimulus, strontium reached higher peak free levels than did calcium (approximately 1.7 times greater), and decayed more slowly (half-decay time 189 ms for strontium and 32 ms for calcium). These differences in calcium and strontium dynamics are likely a consequence of greater strontium permeability through calcium channels, lower affinity of the endogenous buffer for strontium, and less efficient extrusion of strontium. Measurements of presynaptic divalent levels help to explain properties of release evoked by strontium. Parallel fiber synaptic currents triggered by strontium are smaller in amplitude and longer in duration than those triggered by calcium. In both calcium and strontium, release consists of two components, one more steeply dependent on divalent levels than the other. Strontium drives both components less effectively than does calcium, suggesting that the affinities of the sensors involved in both phases of release are lower for strontium than for calcium. Thus, the larger and slower strontium transients account for the prominent slow component of release triggered by strontium. PMID:10096899

Quantifying Calcium Intake in School Age Children: Development and Validation of the Calcium Counts!© Food Frequency Questionnaire

PubMed Central

ZEMEL, BABETTE S.; CAREY, LISA B.; PAULHAMUS, DONNA R.; STALLINGS, VIRGINIA A.; ITTENBACH, RICHARD F.

2014-01-01

Quantifying dietary behavior is difficult and can be intrusive. Calcium, an essential mineral for skeletal development during childhood, is difficult to assess. Few studies have examined the use of food frequency questionnaires (FFQs) for assessing calcium intake in school-age children. This study evaluated the validity and reliability of the Calcium Counts!© FFQ (CCFFQ) for estimating calcium intake in school children in the US. Healthy children, aged 7–10 years (n = 139) completed the CCFFQ and 7-day weighed food records. A subset of subjects completed a second CCFFQ within 3.6 months. Concurrent validity was determined using Pearson correlations between the CCFFQ and food record estimates of calcium intake, and the relationship between quintiles for the two measures. Predictive validity was determined using generalized linear regression models to explore the effects of age, race, and gender. Inter- and intra-individual variability in calcium intake was high (>300 mg/day). Calcium intake was ~300 mg/day higher by CCFFQ compared to food records. Concurrent validity was moderate (r = 0.61) for the entire cohort and higher for selected subgroups. Predictive validity estimates yielded significant relationships between CCFFQ and food record estimates of calcium intake alone and in the presence of such potential effect modifiers as age group, race, and gender. Test–retest reliability was high (r = 0.74). Although calcium intake estimated by the CCFFQ was greater than that measured by food records, the CCFFQ provides valid and reliable estimates of calcium intake in children. The CCFFQ is especially well-suited as a tool to identify children with low calcium intakes. PMID:19621431

Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

PubMed Central

Schröder, Heinz C; Müller, Werner E G

2014-01-01

Summary Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications. PMID:24991497

Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone.

PubMed

Wang, Xiaohong; Schröder, Heinz C; Müller, Werner E G

2014-01-01

Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications.

Neuronal calcium sensor synaptotagmin-9 is not involved in the regulation of glucose homeostasis or insulin secretion.

PubMed

Gustavsson, Natalia; Wang, Xiaorui; Wang, Yue; Seah, Tingting; Xu, Jun; Radda, George K; Südhof, Thomas C; Han, Weiping

2010-11-09

Insulin secretion is a complex and highly regulated process. It is well established that cytoplasmic calcium is a key regulator of insulin secretion, but how elevated intracellular calcium triggers insulin granule exocytosis remains unclear, and we have only begun to define the identities of proteins that are responsible for sensing calcium changes and for transmitting the calcium signal to release machineries. Synaptotagmins are primarily expressed in brain and endocrine cells and exhibit diverse calcium binding properties. Synaptotagmin-1, -2 and -9 are calcium sensors for fast neurotransmitter release in respective brain regions, while synaptotagmin-7 is a positive regulator of calcium-dependent insulin release. Unlike the three neuronal calcium sensors, whose deletion abolished fast neurotransmitter release, synaptotagmin-7 deletion resulted in only partial loss of calcium-dependent insulin secretion, thus suggesting that other calcium-sensors must participate in the regulation of insulin secretion. Of the other synaptotagmin isoforms that are present in pancreatic islets, the neuronal calcium sensor synaptotagmin-9 is expressed at the highest level after synaptotagmin-7. In this study we tested whether synaptotagmin-9 participates in the regulation of glucose-stimulated insulin release by using pancreas-specific synaptotagmin-9 knockout (p-S9X) mice. Deletion of synaptotagmin-9 in the pancreas resulted in no changes in glucose homeostasis or body weight. Glucose tolerance, and insulin secretion in vivo and from isolated islets were not affected in the p-S9X mice. Single-cell capacitance measurements showed no difference in insulin granule exocytosis between p-S9X and control mice. Thus, synaptotagmin-9, although a major calcium sensor in the brain, is not involved in the regulation of glucose-stimulated insulin release from pancreatic β-cells.

Calcium Kinetics During Space Flight

NASA Technical Reports Server (NTRS)

Smith, Scott M.; Wastney, Meryl E.; OBrien, Kimberly O.; Lane, Helen W.

1999-01-01

Bone loss is one of the most detrimental effects of space flight, threatening to limit the duration of human space missions. The ability to understand and counteract this loss will be critical for crew health and safety during and after extended-duration missions. The hypotheses to be tested in this project are that space flight alters calcium homeostasis and bone mineral metabolism, and that calcium homeostasis and bone mineral metabolism will return to baseline within days to weeks of return to Earth. These hypotheses will be evidenced by elevated rates of bone mineral resorption and decreased bone mineral deposition, decreased absorption of dietary calcium, altered calcitropic endocrine profiles, elevated excretion of calcium in urine and feces, and elevated excretion of markers of bone resorption. The second hypothesis will be evidenced by return of indices of calcium homeostasis and bone metabolism to preflight levels within days to weeks of return to Earth. Studies will be conducted on International Space Station astronauts before, during, and after extended-duration flights. Measurements of calcium kinetics, bone mass, and endocrine/biochemical markers of bone and calcium homeostasis will be conducted. Kinetic studies utilizing dual isotope tracer kinetic studies and mathematical modeling techniques will allow for determination of bone calcium deposition, bone calcium resorption, dietary calcium absorption and calcium excretion (both urinary and endogenous fecal excretion). These studies will build upon preliminary work conducted on the Russian Mir space station. The results from this project will be critical for clarifying how microgravity affects bone and calcium homeostasis, and will provide an important control point for assessment of countermeasure efficacy. These results are expected to aid in developing countermeasures for bone loss, both for space crews and for individuals on Earth who have metabolic bone diseases.

Calmodulins from Schistosoma mansoni: Biochemical analysis and interaction with IQ-motifs from voltage-gated calcium channels.

PubMed

Thomas, Charlotte M; Timson, David J

2018-05-17

The trematode Schistosoma mansoni is a causative agent of schistosomiasis, the second most common parasitic disease of humans after malaria. Calcium homeostasis and calcium-mediated signalling pathways are of particular interest in this species. The drug of choice for treating schistosomiasis, praziquantel, disrupts the regulation of calcium uptake and there is interest in exploiting calcium-mediated processes for future drug discovery. Calmodulin is a calcium sensing protein, present in most eukaryotes. It is a critical regulator of processes as diverse as muscle contraction, cell division and, partly through interaction with voltage-gated calcium channels, intra-cellular calcium concentrations. S. mansoni expresses two highly similar calmodulins - SmCaM1 and SmCaM2. Both proteins interact with calcium, manganese, cadmium (II), iron (II) and lead ions in native gel electrophoresis. These ions also cause conformational changes in the proteins resulting in the exposure of a more hydrophobic surface (as demonstrated by anilinonaphthalene-8-sulfonate fluorescence assays). The proteins are primarily dimeric in the absence of calcium ions, but monomeric in the presence of this ion. Both SmCaM1 and SmCaM2 interact with a peptide corresponding to an IQ-motif derived from the α-subunit of the voltage-gated calcium channel SmCa v 1B (residues 1923-1945). Both proteins bound with slightly higher affinity in the presence of calcium ions. However, there was no difference between the affinities of the two proteins for the peptide. This interaction could be antagonised by chlorpromazine and trifluoperazine, but not praziquantel or thiamylal. Interestingly no interaction could be detected with the other three IQ-motifs identified in S. mansoni voltage-gated ion calcium channels. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of soluble calcium on the renneting properties of casein micelles as measured by rheology and diffusing wave spectroscopy.

PubMed

Sandra, S; Ho, M; Alexander, M; Corredig, M

2012-01-01

Addition of calcium chloride to milk has positive effects on cheese-making because it decreases coagulation time, creates firmer gels, and increases curd yield. Although addition of calcium chloride is a widely used industrial practice, the effect of soluble calcium on the preliminary stages of gelation is not fully understood. In addition, it is not known whether the manner of addition and equilibration of the soluble calcium would affect the rennetability of the casein micelles. Therefore, the aim of this paper was to study the details of the coagulation behavior of casein micelles in the presence of additional calcium, and to elucidate whether the manner in which this cation is added (directly as calcium chloride or by gradual exchange through dialysis) affects the functionality of the micelles. Calcium was added as CaCl(2) (1 mM final added concentration) directly to skim milk or indirectly using dialysis against 50 volumes of milk. Additional soluble calcium did not affect the primary phase of the renneting reaction, as demonstrated by the analysis of the casein macropeptide (CMP) released in solution; however, it shortened the coagulation time of the micelles and increased the firmness of the gel. The turbidity parameter of samples with or without calcium showed that similar amounts of CMP were needed for particle interactions to commence. However, the amount of CMP released at the point of gelation, as indicated by rheology, was lesser for samples with added calcium, which can be attributed to a greater extent of calcium bridging on the surface or between micelles. The results also showed that the manner in which calcium was presented to the micelles did not influence the mechanism of gelation. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The calcium concentration of public drinking waters and bottled mineral waters in Spain and its contribution to satisfying nutritional needs.

PubMed

Vitoria, Isidro; Maraver, Francisco; Ferreira-Pêgo, Cíntia; Armijo, Francisco; Moreno Aznar, Luis; Salas-Salvadó, Jordi

2014-07-01

A sufficient intake of calcium enables correct bone mineralization. The bioavailability of calcium in water is similar to that in milk. To determine the concentration of calcium in public drinking water and bottled mineral water. We used ion chromatography to analyse the calcium concentrations of public drinking waters in a representative sample of 108 Spanish municipalities (21,290,707 people) and of 109 natural mineral waters sold in Spain, 97 of which were produced in Spain and 12 of which were imported. The average calcium concentration of public drinking waters was 38.96 ± 32.44 mg/L (range: 0.40- 159.68 mg/L). In 27 municipalities, the water contained 50-100 mg/L of calcium and in six municipalities it contained over 100 mg/L. The average calcium concentration of the 97 Spanish natural mineral water brands was 39.6 mg/L (range: 0.6-610.1 mg/L). Of these, 34 contained 50-100 mg/L of calcium and six contained over 100 mg/L. Of the 12 imported brands, 10 contained over 50 mg/L. Assuming water consumption is as recommended, water containing 50-100 mg/L of calcium provides 5.4-12.8% of the recommended intake of calcium for children aged one to thirteen, up to 13.6% for adolescents, 5.8-17.6% for adults, and up to 20.8% for lactating mothers. Water with 100-150 mg/L of calcium provides 10-31% of the recommended dietary allowance, depending on the age of the individual. Public drinking water and natural mineral water consumption in a third of Spanish cities can be considered an important complementary source of calcium. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Hydrostatic Pressure–Induced Release of Stored Calcium in Cultured Rat Optic Nerve Head Astrocytes

PubMed Central

Mandal, Amritlal; Delamere, Nicholas A.

2010-01-01

Purpose. Elevated intraocular pressure is associated with glaucomatous optic nerve damage. Other investigators have shown functional changes in optic nerve head astrocytes subjected to elevated hydrostatic pressure (HP) for 1 to 5 days. Recently, the authors reported ERK1/2, p90RSK and NHE1 phosphorylation after 2 hours. Here they examine calcium responses at the onset of HP to determine what precedes ERK1/2 phosphorylation. Methods. Cytoplasmic calcium concentration ([Ca2+]i) was measured in cultured rat optic nerve astrocytes loaded with fura-2. The cells were placed in a closed imaging chamber and subjected to an HP increase of 15 mm Hg. Protein phosphorylation was detected by Western blot analysis. Results. The increase of HP caused an immediate slow increase in [Ca2+]i. The response persisted in calcium-free solution and when nickel chloride (4 mM) was added to suppress channel-mediated calcium entry. Previous depletion of the ER calcium stores by cyclopiazonic acid abolished the HP-induced calcium level increase. The HP-induced increase persisted in cells exposed to xestospongin C, an inhibitor of IP3R-mediated calcium release. In contrast, ryanodine receptor (RyR) antagonist ruthenium red (10 μM) or dantrolene (25 μM) inhibited the HP-induced calcium increase. The HP-induced calcium increase was abolished when ryanodine-sensitive calcium stores were pre-depleted with caffeine (3 mM). HP caused ERK1/2 phosphorylation. The magnitude of the ERK1/2 phosphorylation response was reduced by ruthenium red and dantrolene. Conclusions. Increasing HP causes calcium release from a ryanodine-sensitive cytoplasmic store and subsequent ERK1/2 activation. Calcium store release appears to be a required early step in the initial astrocyte response to an HP increase. PMID:20071675

Calcium distribution in Amoeba proteus

PubMed Central

1979-01-01

A preliminary investigation of the distribution of cellular calcium in Amoeba proteus was undertaken. Total cellular calcium under control conditions was found to be 4.59 mmol/kg of cells. When the external Ca++ concentration is increased from the control level of 0.03 to 20 mM, a net Ca++ influx results with a new steady-state cellular calcium level being achieved in integral of 3 h. At steady state the amount of calcium per unit weight of cells is higher than the amount of calcium per unit weight of external solution when the external concentration of Ca++ is below 10 mM. At external Ca++ concentrations above this level, total cellular calcium approaches the medium level of Ca++. Steady- state calcium exchange in Amoeba proteus was determined with 45Ca. There is an immediate and rapid exchange of integral of 0.84 mmol/kg of cells or 18% of the total cellular calcium with the labelled Ca++. Following this initial exchange, there was very little if any further exchange observed. Most of this exchanged calcium could be eliminated from the cell with 1 mM La+++, suggesting that the exchanged calcium is associated with the surface of the cell. Increase in either the external Ca++ concentration of pH raise the amount of exchangeable calcium associated with the cell. Calcium may be associated with the cell surface as a co-ion in the diffuse double layer or bound to fixed negative sites on the surface of the cell. If Ca++-binding sites do exist on the cell surface, there may be more than one type and they may have different dissociation constants. The cytoplasmic Ca++ ion activity is probably maintained at very low levels. PMID:512628

Properties of Ca2+ sparks evoked by action potentials in mouse ventricular myocytes

PubMed Central

Bridge, John H B; Ershler, Philip R; Cannell, Mark B

1999-01-01

Calcium sparks were examined in enzymatically dissociated mouse cardiac ventricular cells using the calcium indicator fluo-3 and confocal microscopy. The properties of the mouse cardiac calcium spark are generally similar to those reported for other species.Examination of the temporal relationship between the action potential and the time course of calcium spark production showed that calcium sparks are more likely to occur during the initial repolarization phase of the action potential. The latency of their occurrence varied by less than 1·4 ms (s.d.) and this low variability may be explained by the interaction of the gating of L-type calcium channels with the changes in driving force for calcium entry during the action potential.When fixed sites within the cell are examined, calcium sparks have relatively constant amplitude but the amplitude of the sparks was variable among sites. The low variability of the amplitude of the calcium sparks suggests that more than one sarcoplasmic reticulum (SR) release channel must be involved in their genesis. Noise analysis (with the assumption of independent gating) suggests that > 18 SR calcium release channels may be involved in the generation of the calcium spark. At a fixed site, the response is close to ‘all-or-none’ behaviour which suggests that calcium sparks are indeed elementary events underlying cardiac excitation-contraction coupling.A method for selecting spark sites for signal averaging is presented which allows the time course of the spark to be examined with high temporal and spatial resolution. Using this method we show the development of the calcium spark at high signal-to-noise levels. PMID:10381593

Bone Is a Major Target of PTH/PTHrP Receptor Signaling in Regulation of Fetal Blood Calcium Homeostasis

PubMed Central

Hirai, Takao; Kobayashi, Tatsuya; Nishimori, Shigeki; Karaplis, Andrew C.; Goltzman, David

2015-01-01

The blood calcium concentration during fetal life is tightly regulated within a narrow range by highly interactive homeostatic mechanisms that include transport of calcium across the placenta and fluxes in and out of bone; the mechanisms of this regulation are poorly understood. Our findings that endochondral bone-specific PTH/PTHrP receptor (PPR) knockout (KO) mice showed significant reduction of fetal blood calcium concentration compared with that of control littermates at embryonic day 18.5 led us to focus on bone as a possibly major determinant of fetal calcium homeostasis. We found that the fetal calcium concentration of Runx2 KO mice was significantly higher than that of control littermates, suggesting that calcium flux into bone had a considerable influence on the circulating calcium concentration. Moreover, Runx2:PTH double mutant fetuses showed calcium levels similar to those of Runx2 KO mice, suggesting that part of the fetal hypocalcemia in PTH KO mice was caused by the increment of the mineralized bone mass allowed by the formation of osteoblasts. Finally, Rank:PTH double mutant mice had a blood calcium concentration even lower than that of the either Rank KO or PTH KO mice alone at embryonic day 18.5. These observations in our genetic models suggest that PTH/PTHrP receptor signaling in bones has a significant role of the regulation of fetal blood calcium concentration and that both placental transport and osteoclast activation contribute to PTH's hypercalcemic action. They also show that PTH-independent deposition of calcium in bone is the major controller of fetal blood calcium level. PMID:26052897

Calcium and Calcium Supplements: Achieving the Right Balance

MedlinePlus

... soy products, cereal and fruit juices, and milk substitutes To absorb calcium, your body also needs vitamin ... Nutrition/default.asp. Accessed June 25, 2015. Calcium. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed ...

Calcium and Vitamin D

MedlinePlus

... A calcium-rich diet (including dairy, nuts, leafy greens and fish) helps to build and protect your bones. Calcium is a mineral that is necessary for life. In addition to building bones and keeping them healthy, calcium enables our ...

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate. (e) When...

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate. (e) When...

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate. (e) When...

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate.(e) When...

Calcium - urine

MedlinePlus

Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... A 24-hour urine sample is most often needed: On day 1, urinate into the toilet when you wake up in the morning. ...

Calcium Modulation of Plant Plasma Membrane-Bound Atpase Activities

NASA Technical Reports Server (NTRS)

Caldwell, C.

1983-01-01

The kinetic properties of barley enzyme are discussed and compared with those of other plants. Possibilities for calcium transport in the plasma membrane by proton pump and ATPase-dependent calcium pumps are explored. Topics covered include the ph phase of the enzyme; high affinity of barley for calcium; temperature dependence, activation enthalpy, and the types of ATPase catalytic sites. Attention is given to lipids which are both screened and bound by calcium. Studies show that barley has a calmodulin activated ATPase that is found in the presence of magnesium and calcium.

Calcium-Alkali Syndrome in the Modern Era

PubMed Central

Patel, Ami M.; Adeseun, Gbemisola A.; Goldfarb, Stanley

2013-01-01

The ingestion of calcium, along with alkali, results in a well-described triad of hypercalcemia, metabolic alkalosis, and renal insufficiency. Over time, the epidemiology and root cause of the syndrome have shifted, such that the disorder, originally called the milk-alkali syndrome, is now better described as the calcium-alkali syndrome. The calcium-alkali syndrome is an important cause of morbidity that may be on the rise, an unintended consequence of shifts in calcium and vitamin D intake in segments of the population. We review the pathophysiology of the calcium-alkali syndrome. PMID:24288027

Process for converting magnesium fluoride to calcium fluoride

DOEpatents

Kreuzmann, A.B.; Palmer, D.A.

1984-12-21

This invention is a process for the conversion of magnesium fluoride to calcium fluoride whereby magnesium fluoride is decomposed by heating in the presence of calcium carbonate, calcium oxide or calcium hydroxide. Magnesium fluoride is a by-product of the reduction of uranium tetrafluoride to form uranium metal and has no known commercial use, thus its production creates a significant storage problem. The advantage of this invention is that the quality of calcium fluoride produced is sufficient to be used in the industrial manufacture of anhydrous hydrogen fluoride, steel mill flux or ceramic applications.

Measurement of the efficacy of calcium silicate for the protection and repair of dental enamel.

PubMed

Parker, Alexander S; Patel, Anisha N; Al Botros, Rehab; Snowden, Michael E; McKelvey, Kim; Unwin, Patrick R; Ashcroft, Alexander T; Carvell, Mel; Joiner, Andrew; Peruffo, Massimo

2014-06-01

To investigate the formation of hydroxyapatite (HAP) from calcium silicate and the deposition of calcium silicate onto sound and acid eroded enamel surfaces in order to investigate its repair and protective properties. Calcium silicate was mixed with phosphate buffer for seven days and the resulting solids analysed for crystalline phases by Raman spectroscopy. Deposition studies were conducted on bovine enamel surfaces. Acid etched regions were produced on the enamel surfaces using scanning electrochemical cell microscopy (SECCM) with acid filled pipettes and varying contact times. Following treatment with calcium silicate, the deposition was visualised with FE-SEM and etch pit volumes were measured by AFM. A second set of bovine enamel specimens were pre-treated with calcium silicate and fluoride, before acid exposure with the SECCM. The volumes of the resultant acid etched pits were measured using AFM and the intrinsic rate constant for calcium loss was calculated. Raman spectroscopy confirmed that HAP was formed from calcium silicate. Deposition studies demonstrated greater delivery of calcium silicate to acid eroded than sound enamel and that the volume of acid etched enamel pits was significantly reduced following one treatment (p<0.05). In the protection study, the intrinsic rate constant for calcium loss from enamel was 0.092 ± 0.008 cm/s. This was significantly reduced, 0.056 ± 0.005 cm/s, for the calcium silicate treatments (p<0.0001). Calcium silicate can transform into HAP and can be deposited on acid eroded and sound enamel surfaces. Calcium silicate can provide significant protection of sound enamel from acid challenges. Calcium silicate is a material that has potential for a new approach to the repair of demineralised enamel and the protection of enamel from acid attacks, leading to significant dental hard tissue benefits. © 2014 Elsevier Ltd. All rights reserved.

A case of gain-of-function mutation in calcium-sensing receptor: supplemental hydration is required for renal protection.

PubMed

Suzuki, M; Aso, T; Sato, T; Michimata, M; Kazama, I; Saiki, H; Hatano, R; Ejima, Y; Miyama, N; Sato, A; Matsubara, M

2005-06-01

The calcium-sensing receptor (CaSR) regulates the extracellular calcium level, mainly by controlling parathyroid hormon secretion and renal calcium reabsorption. In gain-of-function CaSR mutations, the genetic abnormalities increase CaSR activity leading to the development of such clinical manifestations as hypercalciuric hypocalcemia and hypoparathyroidism. We report a Japanese case of CaSR gain-of-function mutation and represent a therapeutic intervention based on the functional characteristics of CaSR in renal tubule. DNA sequence analysis revealed a heterozygous G to T mutation identified in a 12-year-old Japanese girl presenting with sporadic onset of hypercalciuric hypocalcemia and hypoparathyroidism. The mutation is located in the N-terminal extracellular domain of the CaSR gene, one of the most important parts for the three-dimensional construction of the receptor, resulting in the substitution of phenylalanine for cysteine at amino acid 131 (C131F) in exon 3. Based on the diagnosis of the gain-of-function mutation in the CaSR, oral hydrochlorothiazide administration and supplemental hydration were started in addition to calcium supplementation. The combination therapy of thiazide and supplemental hydration markedly reduced both renal calcium excretion and urinary calcium concentration from 0.4-0.7 to less than 0.1 mg/mg (urinary calcium/creatinine ratio) and from 10-15 to 3-5 mg/dl (urinary calcium concentration), respectively. This therapy stopped the progression of renal calcification during the follow-up period. Supplemental hydration should be considered essential for the following reasons: (1) calcium supplementation activates the CaSR in the kidney and suppresses renal urinary concentrating ability, (2) the thiazide has a diuretic effect, (3) as calcium supplementation increases renal calcium excretion, the supplemental hydration decreases urinary calcium concentration by increasing urinary volume, thereby diminishing the risk of intratubular crystallization of calcium ion.

The role of calcium in the prevention of cardiovascular disease--a review of observational studies and randomized clinical trials.

PubMed

Rautiainen, Susanne; Wang, Lu; Manson, JoAnn E; Sesso, Howard D

2013-11-01

Calcium is a mineral that is important for bone health and has also been suggested to play a role in the prevention of cardiovascular disease (CVD). Lately, the potential effects of both inadequate and excessive calcium intake have received growing attention. In this review, we summarize the evidence from experimental, epidemiologic, and clinical studies investigating the role of calcium intake, either from the diet or from supplements, as well as blood concentrations, in relation to the risk of CVD in adults. In vitro and in vivo laboratory studies suggest that calcium may be involved in CVD development through multiple pathways, including blood cholesterol, insulin secretion and sensitivity, vasodilation, inflammatory profile, thrombosis, obesity, and vascular calcification. Several prospective epidemiologic studies have examined how dietary or supplemental calcium intake is associated with CVD incidence or mortality in middle-aged and older adults, and the results are inconsistent. Prospective studies investigating blood concentrations of calcium have also reported mixed results. However, changes in blood calcium concentrations may reflect a disturbed calcium phosphate balance, which is associated with increased risk of CVD. To date there is no randomized clinical trial that has been designed specifically to test the effect of calcium supplementation on the risk of CVD as the primary end point. Existing trials have performed secondary analyses, and most of them have been conducted among postmenopausal women. These trials suggest that calcium supplementation has no effect on CVD development; however, they do not allow a definitive conclusion to be drawn. The average daily intake of calcium is low in many populations; however, the evidence for a potential role of dietary or supplemental calcium in the prevention of CVD remains insufficient and inconclusive. Only large-scale randomized trials designed to investigate the effects of calcium supplementation on CVD events as the primary end point, as well as short-term trials investigating the effect on coronary biomarkers, can provide a definitive answer.

Kit W-sh Mutation Prevents Cancellous Bone Loss during Calcium Deprivation.

PubMed

Lotinun, Sutada; Suwanwela, Jaijam; Poolthong, Suchit; Baron, Roland

2018-01-01

Calcium is essential for normal bone growth and development. Inadequate calcium intake increases the risk of osteoporosis and fractures. Kit ligand/c-Kit signaling plays an important role in regulating bone homeostasis. Mice with c-Kit mutations are osteopenic. The present study aimed to investigate whether impairment of or reduction in c-Kit signaling affects bone turnover during calcium deprivation. Three-week-old male WBB6F1/J-Kit W /Kit W-v /J (W/W v ) mice with c-Kit point mutation, Kit W-sh /HNihrJaeBsmJ (W sh /W sh ) mice with an inversion mutation in the regulatory elements upstream of the c-Kit promoter region, and their wild-type controls (WT) were fed either a normal (0.6% calcium) or a low calcium diet (0.02% calcium) for 3 weeks. μCT analysis indicated that both mutants fed normal calcium diet had significantly decreased cortical thickness and cancellous bone volume compared to WT. The low calcium diet resulted in a comparable reduction in cortical bone volume and cortical thickness in the W/W v and W sh /W sh mice, and their corresponding controls. As expected, the low calcium diet induced cancellous bone loss in the W/W v mice. In contrast, W sh /W sh cancellous bone did not respond to this diet. This c-Kit mutation prevented cancellous bone loss by antagonizing the low calcium diet-induced increase in osteoblast and osteoclast numbers in the W sh /W sh mice. Gene expression profiling showed that calcium deficiency increased Osx, Ocn, Alp, type I collagen, c-Fms, M-CSF, and RANKL/OPG mRNA expression in controls; however, the W sh mutation suppressed these effects. Our findings indicate that although calcium restriction increased bone turnover, leading to osteopenia, the decreased c-Kit expression levels in the W sh /W sh mice prevented the low calcium diet-induced increase in cancellous bone turnover and bone loss but not the cortical bone loss.

An integrated platform for simultaneous multi-well field potential recording and Fura-2-based calcium transient ratiometry in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes.

PubMed

Rast, Georg; Weber, Jürgen; Disch, Christoph; Schuck, Elmar; Ittrich, Carina; Guth, Brian D

2015-01-01

Human induced pluripotent stem cell-derived cardiomyocytes are available from various sources and they are being evaluated for safety testing. Several platforms are available offering different assay principles and read-out parameters: patch-clamp and field potential recording, imaging or photometry, impedance measurement, and recording of contractile force. Routine use will establish which assay principle and which parameters best serve the intended purpose. We introduce a combination of field potential recording and calcium ratiometry from spontaneously beating cardiomyocytes as a novel assay providing a complementary read-out parameter set. Field potential recording is performed using a commercial multi-well multi-electrode array platform. Calcium ratiometry is performed using a fiber optic illumination and silicon avalanche photodetectors. Data condensation and statistical analysis are designed to enable statistical inference of differences and equivalence with regard to a solvent control. Simultaneous recording of field potentials and calcium transients from spontaneously beating monolayers was done in a nine-well format. Calcium channel blockers (e.g. nifedipine) and a blocker of calcium store release (ryanodine) can be recognized and discriminated based on the calcium transient signal. An agonist of L-type calcium channels, FPL 64176, increased and prolonged the calcium transient, whereas BAY K 8644, another L-type calcium channel agonist, had no effect. Both FPL 64176 and various calcium channel antagonists have chronotropic effects, which can be discriminated from typical "chronotropic" compounds, like (±)isoprenaline (positive) and arecaidine propargyl ester (negative), based on their effects on the calcium transient. Despite technical limitations in temporal resolution and exact matching of composite calcium transient with the field potential of a subset of cells, the combined recording platform enables a refined interpretation of the field potential recording and a more reliable identification of drug effects on calcium handling. Copyright © 2015 Elsevier Inc. All rights reserved.

Calcium Absorption from Fortified Ice Cream Formulations Compared with Calcium Absorption from Milk

PubMed Central

van der Hee, Regine M.; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S.M.J.E.; Rietveld, Anton G.; Wilkinson, Joy E.; Quail, Patricia J.; Berry, Mark J.; Dainty, Jack R.; Teucher, Birgit; Fairweather-Tait, Susan J.

2009-01-01

Objective Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Subjects/setting Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Statistical analysis Effects on calcium absorption were evaluated by analysis of variance. Results Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%±8%, 28%±5%, and 31%±9%, respectively, and did not differ significantly (P=0.159). Conclusions Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium. PMID:19394469

Subclinical hypocalcaemia in captive Asian elephants (Elephas maximus).

PubMed

van der Kolk, J H; van Leeuwen, J P T M; van den Belt, A J M; van Schaik, R H N; Schaftenaar, W

2008-04-12

The hypothesis that hypocalcaemia may play a role in dystocia in captive Asian elephants (Elephas maximus) was investigated. The objectives of the study were to measure the total calcium concentration in elephant plasma; assess the changes in parameters of calcium metabolism during a feeding trial; investigate a possible relationship between calcium metabolism and dystocia; and assess bone mineralisation in captive Asian elephants in vivo. The following parameters were measured: total and ionised calcium, inorganic phosphorous and magnesium, the fractional excretions of these minerals, intact parathyroid hormone, 25-OH-D(3) and 1,25-OH-D(3). Radiographs were taken from tail vertebrae for assessment of bone mineralisation. The mean (sd) heparinised plasma total calcium concentration was 2.7 (0.33) mmol/l (n=43) ranging from 0.84 to 3.08 mmol/l in 11 Asian elephants. There was no significant correlation between plasma total calcium concentration and age. Following feeding of a calcium rich ration to four captive Asian elephant cows, plasma total and ionised calcium peaked at 3.6 (0.24) mmol/l (range 3.4 to 3.9 mmol/l) and 1.25 (0.07) mmol/l (range 1.17 to 1.32 mmol/l), respectively. Plasma ionised calcium concentrations around parturition in four Asian elephant cows ranged from 0.37 to 1.1 mmol/l only. The present study indicates that captive Asian elephants might be hypocalcaemic, and that, in captive Asian elephants, the normal plasma concentration of total calcium should actually be around 3.6 mmol/l and normal plasma concentration of ionised calcium around 1.25 mmol/l. Given the fact that elephants absorb dietary calcium mainly from the intestine, it could be concluded that elephants should be fed calcium-rich diets at all times, and particularly around parturition. In addition, normal values for ionised calcium in captive Asian elephants should be reassessed.

Calcium intake of rural Gambian infants: a quantitative study of the relative contributions of breast milk and complementary foods at 3 and 12 months of age.

PubMed

Jarjou, L M A; Goldberg, G R; Coward, W A; Prentice, A

2012-06-01

There is a paucity of information from developing countries on total calcium intake during infancy, and potential consequences for growth and bone development. Observational longitudinal study of rural Gambian infants (13 males and 17 females) at 3 and 12 months of age. Breast-milk intake and calcium concentration, weighed dietary intake, anthropometry, midshaft radius bone mineral content (BMC) and bone width (BW). At 3 and 12 months (mean ± s.d.) calcium intake from breast milk was 179 ± 53 and 117 ± 38, and from other foods 12 ± 38 and 73 ± 105 mg/day. There was no difference in total calcium intake; 94% and 62% of calcium came from breast milk. At 3 and 12 months, weight s.d.-scores were -0.441 ± 1.07 and -1.967 ± 1.06; length s.d.-scores were -0.511 ± 1.04 and -1.469 ± 1.13. Breast-milk calcium intake positively predicted weight (P = 0.0002, P ≤ 0.0001) and length (P = 0.056, P = 0.001). These relationships were not independent of breast-milk intake, which positively predicted weight (P ≤ 0.002) and length (P = 0.06, P = 0.004). At 3, but not 12 months, weight and length correlated with total calcium intake. There were no relationships between total calcium intake and breast-milk intake with BW or BMC. The combination of low calcium intake from breast milk and complementary foods resulted in a low total calcium intake close to the estimated biological requirement for bone mineral accretion. Relationships between calcium intake and growth were largely accounted for by breast-milk intake, suggesting that low calcium intake per se was not the limiting factor in the poor growth. These findings have potential implications for deriving calcium requirements in developing countries.

Na+/H+ exchanger 3 inhibitor diminishes hepcidin-enhanced duodenal calcium transport in hemizygous β-globin knockout thalassemic mice.

PubMed

Charoenphandhu, Narattaphol; Kraidith, Kamonshanok; Lertsuwan, Kornkamon; Sripong, Chanakarn; Suntornsaratoon, Panan; Svasti, Saovaros; Krishnamra, Nateetip; Wongdee, Kannikar

2017-03-01

Recent investigation has shown that the liver-derived iron-regulating hormone, hepcidin, can potentiate intestinal calcium absorption in hemizygous β-globin knockout thalassemic (BKO) mice. Since the upregulation of Fe 2+ and H + cotransporter, divalent metal transporter (DMT)-1, has been shown to correlate with thalassemia-induced intestinal calcium absorption impairment, the inhibition of the apical Na + /H + exchanger (NHE)-3 that is essential for cytoplasmic pH regulation and transepithelial sodium absorption was hypothesized to negatively affect hepcidin action. Herein, the positive effect of hepcidin on the duodenal calcium transport was evaluated using Ussing chamber technique. The results showed that BKO mice had lower absorptive surface area and duodenal calcium transport than wild-type mice. Besides, paracellular transport of zinc in BKO mice was compromised. Hepcidin administration completely restored calcium transport. Since this hepcidin action was totally abolished by inhibitors of the basolateral calcium transporters, Na + /Ca 2+ exchanger (NCX1) and plasma membrane Ca 2+ -ATPase (PMCA 1b ), the enhanced calcium flux potentially occurred through the transcellular pathway rather than paracellular pathway. Interestingly, the selective NHE3 inhibitor, 100 nM tenapanor, markedly inhibited hepcidin-enhanced calcium transport. Accordingly, hepcidin is one of the promising therapeutic agents for calcium malabsorption in β-thalassemia. It mainly stimulates the transcellular calcium transport across the duodenal epithelium in an NHE3-dependent manner.

Formate oxidation-driven calcium carbonate precipitation by Methylocystis parvus OBBP.

PubMed

Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert; Boon, Nico

2014-08-01

Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such asammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2(-1) calcium carbonate precipitate yield was obtained when a culture of 10(9) cells ml(-1) and 5 g of calcium formate liter(-)1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry.

Formate Oxidation-Driven Calcium Carbonate Precipitation by Methylocystis parvus OBBP

PubMed Central

Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert

2014-01-01

Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such as ammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2−1 calcium carbonate precipitate yield was obtained when a culture of 109 cells ml−1 and 5 g of calcium formate liter−1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry. PMID:24837386

Calcium carbonate crystals promote calcium oxalate crystallization by heterogeneous or epitaxial nucleation: possible involvement in the control of urinary lithogenesis.

PubMed

Geider, S; Dussol, B; Nitsche, S; Veesler, S; Berthézène, P; Dupuy, P; Astier, J P; Boistelle, R; Berland, Y; Dagorn, J C; Verdier, J M

1996-07-01

A large proportion of urinary stones have calcium oxalate (CaOx) as the major mineral phase. In these stones, CaOx is generally associated with minor amounts of other calcium salts. Several reports showing the presence of calcium carbonate (CaCO3) and calcium phosphate in renal stones suggested that crystals of those salts might be present in the early steps of stone formation. Such crystals might therefore promote CaOx crystallization from supersaturated urine by providing an appropriate substrate for heterogeneous nucleation. That possibility was investigated by seeding a metastable solution of 45Ca oxalate with vaterite or calcite crystallites. Accretion of CaOx was monitored by 45Ca incorporation. We showed that (1) seeds of vaterite (the hexagonal polymorph of CaCO3) and calcite (the rhomboedric form) could initiate calcium oxalate crystal growth; (2) in the presence of lithostathine, an inhibitor of CaCO3 crystal growth, such accretion was not observed. In addition, scanning electron microscopy demonstrated that growth occurred by epitaxy onto calcite seeds whereas no special orientation was observed onto vaterite. It was concluded that calcium carbonate crystals promote crystallization of calcium oxalate and that inhibitors controlling calcium carbonate crystal formation in Henle's loop might play an important role in the prevention of calcium oxalate stone formation.

Effect of animal and vegetable protein intake on oxalate excretion in idiopathic calcium stone disease.

PubMed

Marangella, M; Bianco, O; Martini, C; Petrarulo, M; Vitale, C; Linari, F

1989-04-01

Oxalate excretion was measured in healthy subjects and idiopathic calcium stone-formers on dietary regimens which differed in the type and amount of protein allowed; 24-h urine collections were obtained from 41 practising vegetarians and 40 normal persons on a free, mixed, "mediterranean" diet. Twenty idiopathic calcium stone-formers were also studied while on two low calcium, low oxalate diets which differed in that animal protein was high in one and restricted in the other. Vegetarians had higher urinary oxalate levels than controls and although the calcium levels were markedly lower, urinary saturation with calcium/oxalate was significantly higher. This mild hypercalciuria was interpreted as being secondary to both a higher intake and increased fractional intestinal absorption of oxalate. Changing calcium stone-formers from a high to a low animal protein intake produced a significant decrease in calcium excretion but there was no variation in urinary oxalate. As a result, the decrease in calcium oxalate saturation was only marginal and not significant. It was concluded that dietary animal protein has a minimal effect on oxalate excretion. Mild hyperoxaluria of idiopathic calcium stone disease is likely to be intestinal in origin. Calcium stone-formers should be advised to avoid an excess of animal protein but the risks of a vegetable-rich diet should also be borne in mind.

Relationship between nutritional habits and hair calcium levels in young women.

PubMed

Jeruszka-Bielak, Marta; Brzozowska, Anna

2011-12-01

The present study was conducted to investigate whether hair calcium levels are related to nutritional habits, selected status parameters, and life-style factors in young women. Eighty-five healthy female students neither pregnant nor lactating, using no hair dyes or permanents were recruited for the study. Food consumption data, including fortified products and dietary supplements were collected with 4-day records. The calcium levels in hair and serum were analyzed by atomic absorption spectroscopy. Serum osteocalcin and the C-terminal telopeptide of type I collagen were assayed by ELISA. The women were divided into four groups according to their total vitamin D and calcium intakes and hair calcium levels. At adequate calcium intake and comparable serum bone biomarker levels, supplemental vitamin D increased the hair calcium levels. On the other hand, at lower than estimated adequate requirement of vitamin D intake the hair calcium levels were comparable in women with low calcium intakes but consuming high amounts of meat products or those whose diets were rich in dairy products, possibly due to homeostatic mechanisms. Elevated hair calcium was seen in 25% of subjects and could not be related to nutritional or life-style factors. The results show that the hair calcium levels were weakly related to the quality of diet, with some synergistic interactions between nutrients, especially vitamin D and magnesium.

Effects of Oxcarbazepine and Levetiracetam on Calcium, Ionized Calcium, and 25-OH Vitamin-D3 Levels in Patients with Epilepsy.

PubMed

Aksoy, Duygu; Güveli, Betül Tekin; Ak, Pelin Doğan; Sarı, Hüseyin; Ataklı, Dilek; Arpacı, Baki

2016-02-29

The primary objective of the present study was to further elucidate the effects of oxcarbazepine (OXC) and levetiracetam (LEV) monotherapies on the bone health status of patients with epilepsy. This study included 48 patients who attended our epilepsy outpatient clinic, had a diagnosis of epilepsy, and were undergoing either OXC or LEV monotherapy and 42 healthy control subjects. The demographic and clinical features of the patients, including gender, age, onset of disease, daily drug dosage, and duration of disease, were noted. Additionally, the calcium, ionized calcium, and 25-OH vitamin-D3 levels of the participants were prospectively evaluated. The 25-OH vitamin-D3, calcium, and ionized calcium levels of the patients taking OXC were significantly lower than those of the control group. These levels did not significantly differ between the patients taking LEV and the control group, but there was a significant negative relationship between daily drug dose and ionized calcium levels in the LEV patients. In the present study, anti-epileptic drugs altered the calcium, ionized calcium, and 25-OH vitamin-D3 levels of epilepsy patients and resulted in bone loss, abnormal mineralization, and fractures. These findings suggest that the calcium, ionized calcium, and 25-OH vitamin-D3 levels of patients with epilepsy should be regularly assessed.

The Role of Calcium in Osteoporosis

NASA Technical Reports Server (NTRS)

Arnaud, C. D.; Sanchez, S. D.

1991-01-01

Calcium requirements may vary throughout the lifespan. During the growth years and up to age 25 to 30, it is important to maximize dietary intake of calcium to maintain positive calcium balance and achieve peak bone mass, thereby possibly decreasing the risk of fracture when bone is subsequently lost. Calcium intake need not be greater than 800 mg/day during the relatively short period of time between the end of bone building and the onset of bone loss (30 to 40 years). Starting at age 40 to 50, both men and women lose bone slowly, but women lose bone more rapidly around the menopause and for about 10 years after. Intestinal calcium absorption and the ability to adapt to low calcium diets are impaired in many postmenopausal women and elderly persons owing to a suspected functional or absolute decrease in the ability of the kidney to produce 1,25(OH)2D2. The bones then become more and more a source of calcium to maintain critical extracellular fluid calcium levels. Excessive dietary intake of protein and fiber may induce significant negative calcium balance and thus increase dietary calcium requirements. Generally, the strongest risk factors for osteoporosis are uncontrollable (e.g., sex, age, and race) or less controllable (e.g., disease and medications). However, several factors such as diet, physical activity, cigarette smoking, and alcohol use are lifestyle related and can be modified to help reduce the risk of osteoporosis.

Interactions between calcium precipitation and the polyphosphate-accumulating bacteria metabolism.

PubMed

Barat, R; Montoya, T; Borrás, L; Ferrer, J; Seco, A

2008-07-01

A sequencing batch reactor that is operated for biological phosphorus removal has been operated under different influent calcium concentrations to study the precipitation process and the possible effects of phosphorus precipitation in the biological phosphorus removal process. Four experiments were carried out under different influent calcium concentrations ranging from 10 to 90 g Ca m(-3). The experimental results and the equilibrium study, which are based on the saturation index calculation, confirm that the process controlling the calcium behaviour is the calcium phosphate precipitation. This precipitation takes place at two stages: initially, precipitation of the amorphous calcium phosphate, and later crystallization of hydroxyapatite. Also the accumulation of phosphorus precipitated was observed when the influent calcium concentration was increased. In all the experiments, the influent wastewater ratio P/COD was kept constant. It has been observed that, at high calcium concentration, the ratio between phosphate release and acetate uptake (P(rel)/Ac(uptake)) decreases. Changes in the polyphosphate-accumulating organism (PAO) population and in the glycogen-accumulating organism (GAO) population during the experimental period were ruled out by means of fluorescence in situ hybridization. These results could suggest that PAO are able to change their metabolic pathways based on external conditions, such as influent calcium concentration. The accumulation of phosphorus precipitated as calcium phosphate at high influent calcium concentration throughout the experimental period confirmed that phosphate precipitation is a process that can affect the PAO metabolism.

Imaging extracellular calcium in endolymph

NASA Astrophysics Data System (ADS)

Strimbu, C. Elliott; Fridberger, Anders

2018-05-01

Hair cell mechanoelectrical transduction and adaptation are believed to be regulated by extracellular calcium. However, the majority of experiments addressing calcium's role have been performed on reduced preparations in conditions that do not mimic those present in vivo. We used confocal microscopy and a low affinity (kd ˜11 µM) ratiometric fluorescent indicator to measure the extracellular calcium concentration in scala media in an in vitro preparation of the guinea pig cochlea. Microelectrodes were used to measure the cochlear microphonic potential during acoustic stimulation. The mean calcium concentration is significantly higher in the tectorial membrane (TM) than the surrounding endolymph, suggesting that the membrane acts as a calcium sink. We also observe calcium hot spots along the underside of the TM, near the outer hair cell bundles and near Hensens stripe close to the inner hair cell bundle. This suggests that the local calcium concentration near the hair bundles exceeds 100 µM, significantly higher than the bulk endolymph. These results were corroborated with fluorescence correlation spectroscopy using a second calcium sensitive dye, Oregon Green 488-BAPTA. Following a brief exposure to loud sound, TM calcium drops dramatically and shows recovery on a similar timescale as the microphonic potential. Our results suggest that the extracellular calcium concentration near the hair bundles is much higher than previously believed and may also serve as a partial control parameter for temporary threshold shifts.

Radiolead (210)Pb and (210)Po/(210)Pb activity ratios in calcium supplements and the assessment of their possible dose to consumers.

PubMed

Strumińska-Parulska, Dagmara I

2016-08-23

This paper presents the results of pioneer study of the most popular calcium supplements as a potential additional source of radiolead (210)Pb in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some came from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The idea was to investigate the naturally occurring (210)Pb activity in different calcium supplements and calculate the annual effective radiation dose from radiolead (210)Pb decay in consumed calcium supplement. The results showed (210)Pb concentrations in natural origin calcium supplements (especially sedimentary rocks) were significantly higher. The highest (210)Pb activity concentrations were determined in mineral tablets made from dolomite - 2.97 ± 0.18 mBq g(-1), while the lowest was observed in organic calcium compounds - both calcium lactate - 0.08 ± 0.01 and 0.13 ± 0.01 mBq g(-1). The highest annual radiation dose from (210)Pb taken with 1 tablet of calcium supplement per day was calculated for soluble calcium lactate sample - 1.19 ± 0.03 µSv year(-1), while the highest annual radiation dose from (210)Pb taken daily with 1 g of pure Ca for dolomite - 5.57 ± 0.34 µSv year(-1).

The effects of thermal stimuli on intracellular calcium change and histamine releases in rat basophilic leukemia mast cells

NASA Astrophysics Data System (ADS)

Wu, Zu-Hui; Zhu, Dan; Chen, Ji-Yao; Zhou, Lu-Wei

2012-05-01

The effects of thermal stimuli on rat basophilic leukemia mast cells were studied. The cells in calcium-contained or calcium-free buffers were thermally stimulated in the temperature range of 25-60 °C. The corresponding calcium ion concentration in cells [Ca2+]i as well as the released histamine from cells was measured with fluorescence staining methods. The ruthenium red (RR), a block of membrane calcium channels (transient receptor potential family V (TRPV)), was used in experiments. Under the stimulus of 25-50 °C, no significant difference on [Ca2+]i was found between these three groups of the cells in calcium-contained buffer without or with RR and cells in calcium-free saline, indicating that the increased calcium in cytosol did not result from the extracellular buffer but came from the intracellular calcium stores. The [Ca2+]i continuously increased under the temperature of 50-60 °C, but the RR and calcium-free saline can obviously diminish the [Ca2+]i increase at these high temperatures, reflecting that the opening of the TRPV2 channels leads to a calcium influx resulting in the [Ca2+]i increment. The histamine release also became significant in these cases. Since the released histamine is a well-known mediator for the microcirculation promotion, the histamine release from mast cells could be one of the mechanisms of thermal therapy.

Calcium in Urine Test: MedlinePlus Lab Test Information

MedlinePlus

... medlineplus.gov/labtests/calciuminurinetest.html Calcium in Urine Test To use the sharing features on this page, ... enable JavaScript. What is a Calcium in Urine Test? A calcium in urine test measures the amount ...

Intracellular sphingosine releases calcium from lysosomes.

PubMed

Höglinger, Doris; Haberkant, Per; Aguilera-Romero, Auxiliadora; Riezman, Howard; Porter, Forbes D; Platt, Frances M; Galione, Antony; Schultz, Carsten

2015-11-27

To elucidate new functions of sphingosine (Sph), we demonstrate that the spontaneous elevation of intracellular Sph levels via caged Sph leads to a significant and transient calcium release from acidic stores that is independent of sphingosine 1-phosphate, extracellular and ER calcium levels. This photo-induced Sph-driven calcium release requires the two-pore channel 1 (TPC1) residing on endosomes and lysosomes. Further, uncaging of Sph leads to the translocation of the autophagy-relevant transcription factor EB (TFEB) to the nucleus specifically after lysosomal calcium release. We confirm that Sph accumulates in late endosomes and lysosomes of cells derived from Niemann-Pick disease type C (NPC) patients and demonstrate a greatly reduced calcium release upon Sph uncaging. We conclude that sphingosine is a positive regulator of calcium release from acidic stores and that understanding the interplay between Sph homeostasis, calcium signaling and autophagy will be crucial in developing new therapies for lipid storage disorders such as NPC.

Calcium, Iron, and Zinc Bioaccessibilities of Australian Sweet Lupin (Lupinus angustifolius L.) Cultivars.

PubMed

Karnpanit, Weeraya; Coorey, Ranil; Clements, Jon; Benjapong, Wenika; Jayasena, Vijay

2017-06-14

In this study, we aimed to determine the effect of the cultivar and dehulling on calcium, iron, and zinc bioaccessibilities of Australian sweet lupin (ASL). Ten ASL cultivars grown in 2011, 2012, and 2013 in Western Australia were used for the study. The bioaccessibilities of calcium, iron, and zinc in whole seed and dehulled lupin samples were determined using a dialysability method. The cultivar had significant effects on calcium, iron, and zinc contents and their bioaccessibilities. Average bioaccessibilities of 6% for calcium, 17% for iron, and 9% for zinc were found for whole seeds. Dehulled ASL had average calcium, iron, and zinc bioaccessibilities of 11%, 21%, and 12%, respectively. Compared to some other pulses, ASL had better iron bioaccessibility and poorer calcium and zinc bioaccessibilities. Dehulling increased calcium bioaccessibilities of almost all lupin cultivars. The effect of dehulling on iron and zinc bioaccessibilities depends on the ASL cultivar.

CalQuo: automated, simultaneous single-cell and population-level quantification of global intracellular Ca2+ responses.

PubMed

Fritzsche, Marco; Fernandes, Ricardo A; Colin-York, Huw; Santos, Ana M; Lee, Steven F; Lagerholm, B Christoffer; Davis, Simon J; Eggeling, Christian

2015-11-13

Detecting intracellular calcium signaling with fluorescent calcium indicator dyes is often coupled with microscopy techniques to follow the activation state of non-excitable cells, including lymphocytes. However, the analysis of global intracellular calcium responses both at the single-cell level and in large ensembles simultaneously has yet to be automated. Here, we present a new software package, CalQuo (Calcium Quantification), which allows the automated analysis and simultaneous monitoring of global fluorescent calcium reporter-based signaling responses in up to 1000 single cells per experiment, at temporal resolutions of sub-seconds to seconds. CalQuo quantifies the number and fraction of responding cells, the temporal dependence of calcium signaling and provides global and individual calcium-reporter fluorescence intensity profiles. We demonstrate the utility of the new method by comparing the calcium-based signaling responses of genetically manipulated human lymphocytic cell lines.

[Calcium phosphate cements in medicine and dentistry--a review of literature].

PubMed

Noetzel, Jörn; Kielbassa, Andrej M

2005-01-01

Calcium phosphates represent the largest group of biominerals in vertebrate animals. They also have many uses in industry, agriculture, medicine and everyday life. The calcium phosphates containing the ionic species HPO4(2-) and PO4(3-) are biologically relevant. In medicine, calcium phosphates have been used for bone regeneration for several decades. The requirement of a mouldable, self-setting material has been fulfilled since the mid-1980s because of the development of calcium phosphate cements. Basically, they consist of a powder (e. g. di-, tri- or tetra-calcium phosphates) that is mixed with a liquid. Their properties depend on kind, amount, and location of each atom within the crystal structure. In dentistry calcium phosphate cements play a secondary role at the moment, although they often have an excellent biocompatibility. This review gives a general idea on development and chemistry of calcium phosphate cements and presents different cement types tested in vitro and in vivo.

Antibacterial action of calcium hydroxide vehicles and calcium hydroxide pastes.

PubMed

Pacios, María Gabriela; Silva, Clara; López, María Elena; Cecilia, Marta

2012-11-01

To evaluate the in vitro action of vehicles alone and with calcium hydroxide against different bacterial species. Agar plates were inoculated with the microbial suspensions, and wells were made and filled with the calcium hydroxide pastes and the vehicles used to prepare the pastes. The zones of inhibited bacterial growth were recorded, and the resulting measurements were statistically analyzed. Enterococcus faecalis was the most resistant microorganism to all medicaments. Calcium hydroxide + p-monochlorophenol; calcium hydroxide + p-monochlorophenol-propylene glycol pastes; and p-monochlorophenol, p-monochlorophenol-propylene glycol, and chlorhexidine gluconate gel alone showed the largest zones of inhibition against all the tested microorganisms. The vehicle used to prepare the calcium hydroxide paste might contribute to its antibacterial action. Chlorhexidine gluconate gel used alone, and camphorated p-monochlorophenol and camphorated p-monochlorophenol-propylene glycol as vehicles of calcium hydroxide, could be recommended, in an antimicrobial sense. © 2012 Wiley Publishing Asia Pty Ltd.

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium citrate. 184.1195 Section 184.1195 Food... Specific Substances Affirmed as GRAS § 184.1195 Calcium citrate. (a) Calcium citrate (Ca3(C6H5O7)2·4H2O, CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric...

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium citrate. 184.1195 Section 184.1195 Food and... Substances Affirmed as GRAS § 184.1195 Calcium citrate. (a) Calcium citrate (Ca3(C6H5O7)2·4H2O, CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with...

Nutrition knowledge, outcome expectations, self-efficacy, and eating behaviors by calcium intake level in Korean female college students.

PubMed

Kim, Min Ju; Kim, Kyung Won

2015-10-01

Calcium is important but deficient in diets of young adult women. This study aimed to examine if cognitive factors and eating behaviors differ according to calcium intake based on the Social Cognitive Theory. Subjects were female college students in Seoul, Korea. Three hundred students completed the questionnaire regarding calcium intake, nutrition knowledge, outcome expectations, self-efficacy and eating behaviors. Data on 240 students were analyzed using t-test or χ(2)-test. Subjects were categorized into two groups, high calcium intake (HC, ≥ 650 mg/day) and low calcium intake (LC, < 650 mg/day), according to recommended intakes of calcium for women aged 19-29 years. The LC group constituted 77.9% of total subjects. Nutrition knowledge was not different according to calcium intake. Three out of 12 outcome expectations items were significantly different between the HC and LC groups. Subjects in the HC group agreed more strongly with the practical benefits of consuming calcium-rich foods, including 'taste' (P < 0.01) and 'going well with other snacks' (P < 0.05), compared to those in the LC group. Negative expectations of 'indigestion' were stronger in the LC group than HC group (P < 0.001). Among self-efficacy items, perceived ability of 'eating dairy foods for snacks' (P < 0.001), 'eating dairy foods every day' (P < 0.01), and 'eating calcium-rich side dishes at meals' (P < 0.05) differed significantly between the HC and LC groups. Eating behaviors including more frequent consumption of dairy foods, fruits or fruit juice (P < 0.001), anchovy, seaweeds, green vegetables, protein-rich foods (P < 0.05), and less frequent consumption of sweets or soft drinks (P < 0.01) were significantly related to calcium intake. This study found that outcome expectations, self-efficacy in consuming calcium-rich foods, and eating behaviors are important in explaining calcium intake. Nutrition education needs to address practical benefits, reduce negative expectations of calcium-rich foods, increase self-efficacy, and modify eating behaviors contributing to calcium intake.

Association of Urinary Calcium Excretion with Serum Calcium and Vitamin D Levels

PubMed Central

Rathod, Anita; Bonny, Olivier; Guessous, Idris; Suter, Paolo M.; Conen, David; Erne, Paul; Binet, Isabelle; Gabutti, Luca; Gallino, Augusto; Muggli, Franco; Hayoz, Daniel; Péchère-Bertschi, Antoinette; Paccaud, Fred

2015-01-01

Background and objectives Population-based data on urinary calcium excretion are scarce. The association of serum calcium and circulating levels of vitamin D [25(OH)D2 or D3] with urinary calcium excretion in men and women from a population-based study was explored. Design, settings, participants, & measurements Multivariable linear regression was used to explore factors associated with square root–transformed 24-hour urinary calcium excretion (milligrams per 24 hours) taken as the dependent variable with a focus on month-specific vitamin D tertiles and serum calcium in the Swiss Survey on Salt Study. Results In total, 624 men and 669 women were studied with mean ages of 49.2 and 47.0 years, respectively (age range=15–95 years). Mean urinary calcium excretion was higher in men than in women (183.05 versus 144.60 mg/24 h; P<0.001). In adjusted models, the association (95% confidence interval) of square root urinary calcium excretion with protein–corrected serum calcium was 1.78 (95% confidence interval, 1.21 to 2.34) mg/24 h per milligram per deciliter in women and 0.59 (95% confidence interval, −0.11 to 1.29) mg/24 h per milligram per deciliter in men. Men in the third 25(OH)D3 tertile had higher square root urinary calcium excretion than men in the first tertile (0.99; 95% confidence interval, 0.36 to 1.63 mg/24 h per nanogram per milliliter), and the corresponding association was 0.32 (95% confidence interval, −0.22 to 0.85) mg/24 h per nanogram per milliliter in women. These sex differences were more marked under conditions of high urinary sodium or urea excretions. Conclusions There was a positive association of serum calcium with urinary calcium excretion in women but not men. Vitamin 25(OH)D3 was associated with urinary calcium excretion in men but not women. These results suggest important sex differences in the hormonal and dietary control of urinary calcium excretion. PMID:25518946

Calcium Acetate or Calcium Carbonate for Hyperphosphatemia of Hemodialysis Patients: A Meta-Analysis

PubMed Central

Zhang, Han; Yang, Bo; Mao, Zhiguo

2015-01-01

Background High levels of serum phosphorus both at baseline and during follow-up are associated with increased mortality in dialysis patients, and administration of phosphate binders was independently associated with improved survival among hemodialysis population. Calcium-based phosphate binders are the most commonly used phosphate binders in developing countries for their relatively low costs. Objectives To compare the efficacy and safety between calcium carbonate and calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients. Methods PubMed, EMBASE, Cochrane Library, Google scholar and Chinese databases (Wanfang, Weipu, National Knowledge Infrastructure of China) were searched for relevant studies published before March 2014. Reference lists of nephrology textbooks and review articles were checked. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of calcium acetate and calcium carbonate in adult patients with MHD was performed using Review Manager 5.0. Results A total of ten studies (625 participants) were included in this meta-analysis. There was insufficient data in all-cause mortality and cardiovascular events for meta-analysis. Compared with calcium carbonate group, the serum phosphorus was significantly lower in calcium acetate group after4 weeks’ administration (MD -0.15 mmol/L, 95% CI -0.28 to -0.01) and after 8 weeks’ administration (MD -0.25 mmol/L, 95% CI -0.40 to -0.11). There was no difference in serum calcium levels or the incidence of hypercalcemia between two groups at 4 weeks and 8 weeks. No statistical difference was found in parathyroid hormone (PTH) levels or serum calcium by phosphorus (Ca x P) product. There was significantly higher risk of intolerance with calcium acetate treatment (RR 3.46, 95% CI 1.48 to 8.26). Conclusions For hyperphosphatemia treatment, calcium acetate showed better efficacy and with a higher incidence of intolerance compared with calcium carbonate. There are insufficient data to establish the comparative superiority of the two calcium-based phosphate binders on all-cause mortality and cardiovascular end-points in hemodialysis patients. PMID:25799184

Genome-wide analysis of wheat calcium ATPases and potential role of selected ACAs and ECAs in calcium stress.

PubMed

Aslam, Roohi; Williams, Lorraine E; Bhatti, Muhammad Faraz; Virk, Nasar

2017-10-27

P 2 - type calcium ATPases (ACAs-auto inhibited calcium ATPases and ECAs-endoplasmic reticulum calcium ATPases) belong to the P- type ATPase family of active membrane transporters and are significantly involved in maintaining accurate levels of Ca 2+ , Mn 2+ and Zn 2+ in the cytosol as well as playing a very important role in stress signaling, stomatal opening and closing and pollen tube growth. Here we report the identification and possible role of some of these ATPases from wheat. In this study, ACA and ECA sequences of six species (belonging to Poaceae) were retrieved from different databases and a phylogenetic tree was constructed. A high degree of evolutionary relatedness was observed among P 2 sequences characterized in this study. Members of the respective groups from different plant species were observed to fall under the same clade. This pattern highlights the common ancestry of P 2- type calcium ATPases. Furthermore, qRT-PCR was used to analyse the expression of selected ACAs and ECAs from Triticum aestivum (wheat) under calcium toxicity and calcium deficiency. The data indicated that expression of ECAs is enhanced under calcium stress, suggesting possible roles of these ATPases in calcium homeostasis in wheat. Similarly, the expression of ACAs was significantly different in plants grown under calcium stress as compared to plants grown under control conditions. This gives clues to the role of ACAs in signal transduction during calcium stress in wheat. Here we concluded that wheat genome consists of nine P 2B and three P 2A -type calcium ATPases. Moreover, gene loss events in wheat ancestors lead to the loss of a particular homoeolog of a gene in wheat. To elaborate the role of these wheat ATPases, qRT-PCR was performed. The results indicated that when plants are exposed to calcium stress, both P 2A and P 2B gene expression get enhanced. This further gives clues about the possible role of these ATPases in wheat in calcium management. These findings can be useful in future for genetic manipulations as well as in wheat genome annotation process.

Canonical Transient Receptor Potential Channel 2 (TRPC2) as a Major Regulator of Calcium Homeostasis in Rat Thyroid FRTL-5 Cells

PubMed Central

Sukumaran, Pramod; Löf, Christoffer; Kemppainen, Kati; Kankaanpää, Pasi; Pulli, Ilari; Näsman, Johnny; Viitanen, Tero; Törnquist, Kid

2012-01-01

Mammalian non-selective transient receptor potential cation channels (TRPCs) are important in the regulation of cellular calcium homeostasis. In thyroid cells, including rat thyroid FRTL-5 cells, calcium regulates a multitude of processes. RT-PCR screening of FRTL-5 cells revealed the presence of TRPC2 channels only. Knockdown of TRPC2 using shRNA (shTRPC2) resulted in decreased ATP-evoked calcium peak amplitude and inward current. In calcium-free buffer, there was no difference in the ATP-evoked calcium peak amplitude between control cells and shTRPC2 cells. Store-operated calcium entry was indistinguishable between the two cell lines. Basal calcium entry was enhanced in shTRPC2 cells, whereas the level of PKCβ1 and PKCδ, the activity of sarco/endoplasmic reticulum Ca2+-ATPase, and the calcium content in the endoplasmic reticulum were decreased. Stromal interaction molecule (STIM) 2, but not STIM1, was arranged in puncta in resting shTRPC2 cells but not in control cells. Phosphorylation site Orai1 S27A/S30A mutant and non-functional Orai1 R91W attenuated basal calcium entry in shTRPC2 cells. Knockdown of PKCδ with siRNA increased STIM2 punctum formation and enhanced basal calcium entry but decreased sarco/endoplasmic reticulum Ca2+-ATPase activity in wild-type cells. Transfection of a truncated, non-conducting mutant of TRPC2 evoked similar results. Thus, TRPC2 functions as a major regulator of calcium homeostasis in rat thyroid cells. PMID:23144458

Reduction of orthophosphates loss in agricultural soil by nano calcium sulfate.

PubMed

Chen, Dong; Szostak, Paul; Wei, Zongsu; Xiao, Ruiyang

2016-01-01

Nutrient loss from soil, especially phosphorous (P) from farmlands to natural water bodies via surface runoff or infiltration, have caused significant eutrophication problems. This is because dissolved orthophosphates are usually the limiting nutrient for algal blooms. Currently, available techniques to control eutrophication are surprisingly scarce. Calcium sulfate or gypsum is a common soil amendment and has a strong complexation to orthophosphates. The results showed that calcium sulfate reduced the amount of water extractable P (WEP) through soil incubation tests, suggesting less P loss from farmlands. A greater decrease in WEP occurred with a greater dosage of calcium sulfate. Compared to conventional coarse calcium sulfate, nano calcium sulfate further reduced WEP by providing a much greater specific surface area, higher solubility, better contact with the fertilizer and the soil particles, and superior dispersibility. The enhancement of the nano calcium sulfate for WEP reduction is more apparent for a pellet- than a powdered- fertilizer. At the dosage of Ca/P weight ratio of 2.8, the WEP decreased by 31±5% with the nano calcium sulfate compared to 20±5% decrease with the coarse calcium sulfate when the pellet fertilizer was used. Computation of the chemical equilibrium speciation shows that calcium hydroxyapatite has the lowest solubility. However, other mineral phases such as hydroxydicalcium phosphate, dicalcium phosphate dihydrate, octacalcium phosphate, and tricalcium phosphate might form preceding to calcium hydroxyapatite. Since calcium sulfate is the major product of the flue gas desulfurization (FGD) process, this study demonstrates a potential beneficial reuse and reduction of the solid FGD waste. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of aluminum on bidirectional calcium flux in rat everted intestinal sacs.

PubMed

Adler, A J; Zara, C; Berlyne, G M

1989-09-01

The effect of aluminum on intestinal calcium absorption was determined in male Sprague-Dawley rats using an everted intestinal sac technique. Bidirectional calcium flux in the duodena and ilea of normal rats was assessed by means of dual calcium isotopes. Two micromolar aluminum significantly inhibited net calcium absorption (J net) in the duodenum through suppression of mucosato-serosa flux (J m----s). Jm----s was reduced from 2.21 +/- 0.50 mumol Ca.h-1.g wet wt-1 in controls to 0.93 +/- 0.35 mumol Ca.h-1.g-1 in aluminum exposed sacs, and Jnet was reduced from 1.88 +/- 0.14 mumol Ca.h-1.g-1 to 0.55 +/- 0.41 mumol Ca.h-1.g-1 (P less than 0.001). Serosa-to-mucosa calcium flux (Js----m) was not similarly influenced by aluminum. Inhibition of Jm----s occurred whether aluminum was initially present on the mucosal or serosal side of the duodenal sac and inhibition of Jnet calcium by 2 muM A1 occurred at all ambient concentrations of calcium studied. In the ileum, aluminum had no effect on any component of calcium flux. Aluminum did not induce any suppression of glucose transport in either the duodenum or ileum, suggesting that the effect on calcium transport is relatively specific. These results suggest that aluminum inhibits calcium absorption in the duodenum through an effect on active mucosa-to-serosa transport, but has no effect on ileal calcium absorption, which in the rat is not mediated by an active process.

Solubility and bioavailability of stabilized amorphous calcium carbonate.

PubMed

Meiron, Oren E; Bar-David, Elad; Aflalo, Eliahu D; Shechter, Assaf; Stepensky, David; Berman, Amir; Sagi, Amir

2011-02-01

Since its role in the prevention of osteoporosis in humans was proven some 30 years ago, calcium bioavailability has been the subject of numerous scientific studies. Recent technology allowing the production of a stable amorphous calcium carbonate (ACC) now enables a bioavailability analysis of this unique form of calcium. This study thus compares the solubility and fractional absorption of ACC, ACC with chitosan (ACC-C), and crystalline calcium carbonate (CCC). Solubility was evaluated by dissolving these preparations in dilute phosphoric acid. The results demonstrated that both ACC and ACC-C are more soluble than CCC. Fractional absorption was evaluated by intrinsically labeling calcium carbonate preparations with (45)Ca, orally administrated to rats using gelatin capsules. Fractional absorption was determined by evaluating the percentage of the administrated radioactive dose per milliliter that was measured in the serum, calcium absorption in the femur, and whole-body retention over a 34-hour period. Calcium serum analysis revealed that calcium absorption from ACC and ACC-C preparations was up to 40% higher than from CCC, whereas retention of ACC and ACC-C was up to 26.5% higher than CCC. Absorbed calcium in the femurs of ACC-administrated rats was 30% higher than in CCC-treated animals, whereas 15% more calcium was absorbed following ACC-C treatment than following CCC treatment. This study demonstrates the enhanced solubility and bioavailability of ACC over CCC. The use of stable ACC as a highly bioavailable dietary source for calcium is proposed based on the findings of this study. Copyright © 2011 American Society for Bone and Mineral Research.

Real-time In Vivo Recording of Arabidopsis Calcium Signals During Insect Feeding Using a Fluorescent Biosensor

PubMed Central

Vincent, Thomas R.; Canham, James; Toyota, Masatsugu; Avramova, Marieta; Mugford, Sam T.; Gilroy, Simon; Miller, Anthony J.; Hogenhout, Saskia; Sanders, Dale

2017-01-01

Calcium ions are predicted to be key signaling entities during biotic interactions, with calcium signaling forming an established part of the plant defense response to microbial elicitors and to wounding caused by chewing insects, eliciting systemic calcium signals in plants. However, the role of calcium in vivo during biotic stress is still unclear. This protocol describes the use of a genetically-encoded calcium sensor to detect calcium signals in plants during feeding by a hemipteran pest. Hemipterans such as aphids pierce a small number of cells with specialized, elongated sucking mouthparts, making them the ideal tool to study calcium dynamics when a plant is faced with a biotic stress, which is distinct from a wounding response. In addition, fluorescent biosensors are revolutionizing the measurement of signaling molecules in vivo in both animals and plants. Expressing a GFP-based calcium biosensor, GCaMP3, in the model plant Arabidopsis thaliana allows for the real-time imaging of plant calcium dynamics during insect feeding, with a high spatial and temporal resolution. A repeatable and robust assay has been developed using the fluorescence microscopy of detached GCaMP3 leaves, allowing for the continuous measurement of cytosolic calcium dynamics before, during, and after insect feeding. This reveals a highly-localized rapid calcium elevation around the aphid feeding site that occurs within a few minutes. The protocol can be adapted to other biotic stresses, such as additional insect species, while the use of Arabidopsis thaliana allows for the rapid generation of mutants to facilitate the molecular analysis of the phenomenon. PMID:28829425

The use of flow cytometry to examine calcium signalling by TRPV1 in mixed cell populations.

PubMed

Assas, Bakri M; Abdulaal, Wesam H; Wakid, Majed H; Zakai, Haytham A; Miyan, J; Pennock, J L

2017-06-15

Flow cytometric analysis of calcium mobilisation has been in use for many years in the study of specific receptor engagement or isolated cell:cell communication. However, calcium mobilisation/signaling is key to many cell functions including apoptosis, mobility and immune responses. Here we combine multiplex surface staining of whole spleen with Indo-1 AM to visualise calcium mobilisation and examine calcium signaling in a mixed immune cell culture over time. We demonstrate responses to a TRPV1 agonist in distinct cell subtypes without the need for cell separation. Multi parameter staining alongside Indo-1 AM to demonstrate calcium mobilization allows the study of real time calcium signaling in a complex environment. Copyright © 2017. Published by Elsevier Inc.

SECONDARY HYPERPARATHYROIDISM AFTER BARIATRIC SURGERY: TREATMENT IS WITH CALCIUM CARBONATE OR CALCIUM CITRATE?

PubMed Central

BARETTA, Giorgio Alfredo Pedroso; CAMBI, Maria Paula Carlini; RODRIGUES, Arieli Luz; MENDES, Silvana Aparecida

2015-01-01

Background : Bariatric surgery, especially Roux-en-Y gastric bypass, can cause serious nutritional complications arising from poor absorption of essential nutrients. Secondary hyperparathyroidism is one such complications that leads to increased parathyroid hormone levels due to a decrease in calcium and vitamin D, which may compromise bone health. Aim : To compare calcium carbonate and calcium citrate in the treatment of secondary hyperparathyroidism. Method : Patients were selected on the basis of their abnormal biochemical test and treatment was randomly done with citrate or calcium carbonate. Results : After 60 days of supplementation, biochemical tests were repeated, showing improvement in both groups. Conclusion : Supplementation with calcium (citrate or carbonate) and vitamin D is recommended after surgery for prevention of secondary hyperparathyroidism. PMID:26537273

Measuring calcium dynamics in living cells with Genetically Encodable Calcium Indicators

PubMed Central

McCombs, Janet E.

2008-01-01

Genetically encoded calcium indicators (GECIs) allow researchers to measure calcium dynamics in specific targeted locations within living cells. Such indicators enable dissection of the spatial and temporal control of calcium signaling processes. Here we review recent progress in the development of GECIs, highlighting which indicators are most appropriate for measuring calcium in specific organelles and localized domains in mammalian tissue culture cells. An overview of recent approaches that have been undertaken to ensure that the GECIs are minimally perturbed by the cellular environment is provided. Additionally, the procedures for introducing GECIs into mammalian cells, conducting calcium imaging experiments, and analyzing data are discussed. Because organelle-targeted indicators often pose an additional challenge, we underscore strategies for calibrating GECIs in these locations. PMID:18848629

Inappropriate phosphate excretion in idiopathic hypercalciuria: the key to a common cause and future treatment?

PubMed Central

Williams, C P; Child, D F; Hudson, P R; Soysa, L D; Davies, G K; Davies, M G; De Bolla, A R

1996-01-01

AIMS: To present experimental evidence in support of a proposed common cause for absorptive hypercalciuria, renal hypercalciuria, renal phosphate leak and enhancement of 1,25-(OH)2-vitamin D concentrations in patients presenting with renal stone disease; and to suggest further investigation with a view to new management. METHODS: An oral calcium loading test was administered to 15 patients with renal stones and 10 normal controls in the fasting state: urine and blood were collected hourly. After the second urine sample, 400 mg calcium dissolved in water was administered orally. Serum calcium, albumin, parathyroid hormone (PTH), and phosphate were measured together with urine calcium clearance and urinary phosphate from which the TmPO4/glomerular filtration rate (GFR) ratio was calculated. Serum 1,25-(OH)2-vitamin D was measured in the first serum sample. In addition, 24 hour urine calcium results were collected retrospectively from the patients' case notes over the previous 18 months. RESULTS: In the basal state, renal stone patients had an overall greater phosphaturia (lower TmPO4/GFR: median 1.72 compared with 2.10 in controls) and increased calcium clearance. Serum corrected calcium and PTH concentrations did not differ between the groups. After calcium loading, serum calcium and urine calcium clearance rose in both groups, with patients with renal stones experiencing a greater percentage fall in phosphaturia. In both groups TmPO4/GFR fell (greater phosphaturia) with increased serum corrected calcium, with the patients showing notably greater phosphaturia for any given calcium concentration. Patients also had notably greater phosphaturia compared with the serum calcium concentration for any given PTH value. Serum 1,25-(OH)2-vitamin D was higher in patients than controls and for any 1,25-(OH)2-vitamin D concentration phosphaturia measured against serum calcium was greater in patients than controls. 1,25-(OH)2-vitamin D did not correlate with phosphaturia relative to serum calcium concentrations within the patient and control groups. CONCLUSIONS: It is proposed that patients with idiopathic hypercalciuria have an "inappropriately' high phosphate excretion for any given serum calcium concentration. Loss of phosphate may induce increased activation of 1,25-(OH)2-vitamin D. Some of the commonly described causes of stone formation may be manifestations of a single mechanism. PMID:8944605

Changes in urinary risk profile after short-term low sodium and low calcium diet in recurrent Swiss kidney stone formers.

PubMed

Seeger, Harald; Kaelin, Andrea; Ferraro, Pietro M; Weber, Damian; Jaeger, Philippe; Ambuehl, Patrice; Robertson, William G; Unwin, Robert; Wagner, Carsten A; Mohebbi, Nilufar

2017-12-04

Kidney stone disease is common in industrialized countries. Recently, it has attracted growing attention, because of its significant association with adverse renal outcomes, including end stage renal disease. Calcium-containing kidney stones are frequent with high recurrence rates. While hypercalciuria is a well-known risk factor, restricted intake of animal protein and sodium, combined with normal dietary calcium, has been shown to be more effective in stone prevention compared with a low-calcium diet. Notably, the average sodium intake in Switzerland is twice as high as the WHO recommendation, while the intake of milk and dairy products is low. We retrospectively analyzed Swiss recurrent kidney stone formers (rKSF) to test the impact of a low-sodium in combination with a low-calcium diet on the urinary risk profile. In patients with recurrent calcium oxalate containing stones, we investigated both, the consequence of a low-sodium diet on urinary volume and calcium excretion, and the influence of a low-sodium low-calcium diet on urinary oxalate excretion. Of the 169 patients with CaOx stones, 49 presented with hypercalciuria at baseline. The diet resulted in a highly significant reduction in 24-h urinary sodium and calcium excretion: from 201 ± 89 at baseline to 128 ± 88 mmol/d for sodium (p < 0.0001), and from 5.67 ± 3.01 to 4.06 ± 2.46 mmol/d (p < 0.0001) for calcium, respectively. Urine volume remained unchanged. Notably, no increase in oxalate excretion occurred on the restricted diet (0.39 ± 0.26 vs 0.39 ± 0.19 mmol/d, p = 0.277). Calculated Psf (probability of stone formation) values were only predictive for the risk of calcium phosphate stones. A diet low in sodium and calcium in recurrent calcium oxalate stone formers resulted in a significant reduction of urinary calcium excretion, but no change in urine volume. In this population with apparently low intake of dairy products, calcium restriction does not necessarily result in increased urinary oxalate excretion. However, based on previous studies, we recommend a normal dietary calcium intake to avoid a potential increase in urinary oxalate excretion and unfavorable effects on bone metabolism in hypercalciuric KSFs.

Calcium supplementation in osteoporosis: useful or harmful?

PubMed

Chiodini, Iacopo; Bolland, Mark J

2018-04-01

Osteoporosis and fragility fractures are important social and economic problems worldwide and are due to both the loss of bone mineral density and sarcopenia. Indeed, fragility fractures are associated with increased disability, morbidity and mortality. It is known that a normal calcium balance together with a normal vitamin D status is important for maintaining well-balanced bone metabolism, and for many years, calcium and vitamin D have been considered crucial in the prevention and treatment of osteoporosis. However, recently, the usefulness of calcium supplementation (alone or with concomitant vitamin D) has been questioned, since some studies reported only weak efficacy of these supplementations in reducing fragility fracture risk. On the other hand, besides the gastrointestinal side effects of calcium supplements and the risk of kidney stones related to use of co-administered calcium and vitamin D supplements, other recent data suggested potential adverse cardiovascular effects from calcium supplementation. This debate article is focused on the evidence regarding both the possible usefulness for bone health and the potential harmful effects of calcium and/or calcium with vitamin D supplementation. © 2018 European Society of Endocrinology.

Mechanically induced intercellular calcium communication in confined endothelial structures.

PubMed

Junkin, Michael; Lu, Yi; Long, Juexuan; Deymier, Pierre A; Hoying, James B; Wong, Pak Kin

2013-03-01

Calcium signaling in the diverse vascular structures is regulated by a wide range of mechanical and biochemical factors to maintain essential physiological functions of the vasculature. To properly transmit information, the intercellular calcium communication mechanism must be robust against various conditions in the cellular microenvironment. Using plasma lithography geometric confinement, we investigate mechanically induced calcium wave propagation in networks of human umbilical vein endothelial cells organized. Endothelial cell networks with confined architectures were stimulated at the single cell level, including using capacitive force probes. Calcium wave propagation in the network was observed using fluorescence calcium imaging. We show that mechanically induced calcium signaling in the endothelial networks is dynamically regulated against a wide range of probing forces and repeated stimulations. The calcium wave is able to propagate consistently in various dimensions from monolayers to individual cell chains, and in different topologies from linear patterns to cell junctions. Our results reveal that calcium signaling provides a robust mechanism for cell-cell communication in networks of endothelial cells despite the diversity of the microenvironmental inputs and complexity of vascular structures. Copyright © 2012 Elsevier Ltd. All rights reserved.

Calcium Supplements and Cardiovascular Disease: A Review.

PubMed

Waldman, Talya; Sarbaziha, Raheleh; Merz, C Noel Bairey; Shufelt, Chrisandra

2015-07-01

Dietary or supplemental calcium intake has long been encouraged for optimal bone health. However, more recently, the safety of calcium supplementation has been questioned because of a possible association between supplemental calcium and cardiovascular risk. Whereas calcium may have a beneficial or neutral effect on cardiovascular risk factors such as blood pressure, cholesterol, weight, and diabetes, available evidence does not provide a definitive answer for an association with cardiovascular disease (CVD). To date, no calcium trials have studied cardiovascular disease as a primary end point, and larger trials with longer follow-up are needed. In this review, we present results from observational studies and randomized controlled trials (RCTs) that have evaluated calcium intake (dietary or supplemental) in relation to cardiovascular risk factors and cardiovascular disease as a secondary outcome. Results from RCTs are mixed regarding CVD risk in those using supplemental calcium with or without vitamin D, and more large-scale randomized trials designed specifically with CVD as the primary end point are needed. Evidence suggests that it is reasonable to encourage adequate dietary calcium intake, especially for postmenopausal women who are at greatest risk for osteoporotic fracture.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramer, L.

The effect of drugs such as glucocorticoids and thyroid extract on calcium metabolism is unknown. However, several other medications affect the excretion and intestinal absorption of calcium. A controlled study was carried out to investigate these aspects. Urinary calcium was determined for 3 months during the long-term intake of the antituberculous drug isoniazid (INH) and of the antibiotic tetracycline. The effect of the diuretics furosemide and hydrochlorothiazide, of several aluminum-containing antacids, of thyroid extract and of corticosteroids was also studied. Metabolic balances of calcium, phosphorus, magnesium and zinc were determined, as well as the intestinal absorption of calcium using Camore » 47. Plasma levels, urinary and fecal excretions of Ca 47 were determined. All drugs tested increased urinary calcium except for the diuretic hydrochlorothiazide. Regarding the effect of corticosteroids: the intestinal absorption of calcium was unchanged after the short-term use and was very high after long-term use. The studies have shown that several commonly used drugs induce an increase in urinary calcium excretion which may contribute to calcium loss, if this increase persists for prolonged periods of time. Urinary excretions of phosphorus, magnesium and zinc increased in some of the studies.« less

Calcium metabolism before, during, and after a 3-mo spaceflight: kinetic and biochemical changes

NASA Technical Reports Server (NTRS)

Smith, S. M.; Wastney, M. E.; Morukov, B. V.; Larina, I. M.; Nyquist, L. E.; Abrams, S. A.; Taran, E. N.; Shih, C. Y.; Nillen, J. L.; Davis-Street, J. E.;

Activity-Dependent Gating of Calcium Spikes by A-type K+ Channels Controls Climbing Fiber Signaling in Purkinje Cell Dendrites

PubMed Central

Otsu, Yo; Marcaggi, Païkan; Feltz, Anne; Isope, Philippe; Kollo, Mihaly; Nusser, Zoltan; Mathieu, Benjamin; Kano, Masanobu; Tsujita, Mika; Sakimura, Kenji; Dieudonné, Stéphane

2014-01-01

Summary In cerebellar Purkinje cell dendrites, heterosynaptic calcium signaling induced by the proximal climbing fiber (CF) input controls plasticity at distal parallel fiber (PF) synapses. The substrate and regulation of this long-range dendritic calcium signaling are poorly understood. Using high-speed calcium imaging, we examine the role of active dendritic conductances. Under basal conditions, CF stimulation evokes T-type calcium signaling displaying sharp proximodistal decrement. Combined mGluR1 receptor activation and depolarization, two activity-dependent signals, unlock P/Q calcium spikes initiation and propagation, mediating efficient CF signaling at distal sites. These spikes are initiated in proximal smooth dendrites, independently from somatic sodium action potentials, and evoke high-frequency bursts of all-or-none fast-rising calcium transients in PF spines. Gradual calcium spike burst unlocking arises from increasing inactivation of mGluR1-modulated low-threshold A-type potassium channels located in distal dendrites. Evidence for graded activity-dependent CF calcium signaling at PF synapses refines current views on cerebellar supervised learning rules. PMID:25220810

Apo calmodulin binding to the L-type voltage-gated calcium channel Ca{sub v}1.2 IQ peptide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian Luyun; Myatt, Daniel; Kitmitto, Ashraf

2007-02-16

The influx of calcium through the L-type voltage-gated calcium channels (LTCCs) is the trigger for the process of calcium-induced calcium release (CICR) from the sarcoplasmic recticulum, an essential step for cardiac contraction. There are two feedback mechanisms that regulate LTCC activity: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF), both of which are mediated by calmodulin (CaM) binding. The IQ domain (aa 1645-1668) housed within the cytoplasmic domain of the LTCC Ca{sub v}1.2 subunit has been shown to bind both calcium-loaded (Ca{sup 2+}CaM ) and calcium-free CaM (apoCaM). Here, we provide new data for the structural basis for the interaction ofmore » apoCaM with the IQ peptide using NMR, revealing that the apoCaM C-lobe residues are most significantly perturbed upon complex formation. In addition, we have employed transmission electron microscopy of purified LTCC complexes which shows that both apoCaM and Ca{sup 2+}CaM can bind to the intact channel.« less

Delay in onset of metabolic alkalosis during regional citrate anti-coagulation in continuous renal replacement therapy with calcium-free replacement solution.

PubMed

See, Kay Choong; Lee, Margaret; Mukhopadhyay, Amartya

2009-01-01

Regional citrate anti-coagulation for continuous renal replacement therapy chelates calcium to produce the anti- coagulation effect. We hypothesise that a calcium-free replacement solution will require less citrate and produce fewer metabolic side effects. Fifty patients, in a Medical Intensive Care Unit of a tertiary teaching hospital (25 in each group), received continuous venovenous hemofiltration using either calcium-containing or calcium-free replacement solutions. Both groups had no significant differences in filter life, metabolic alkalosis, hypernatremia, hypocalcemia, and hypercalcemia. However, patients using calcium-containing solution developed metabolic alkalosis earlier, compared to patients using calcium-free solution (mean 24.6 hours,CI 0.8-48.4 vs. 37.2 hours, CI 9.4-65, P = 0.020). When calcium-containing replacement solution was used, more citrate was required (mean 280 ml/h, CI 227.2-332.8 vs. 265 ml/h, CI 203.4-326.6, P = 0.069), but less calcium was infused (mean 21.2 ml/h, CI 1.2-21.2 vs 51.6 ml/h, CI 26.8-76.4, P < or = 0.0001).

Calcium Orthophosphates in Nature, Biology and Medicine

PubMed Central

Dorozhkin, Sergey V.

2009-01-01

The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. These materials are of the special significance because they represent the inorganic part of major normal (bones, teeth and dear antlers) and pathological (i.e. those appearing due to various diseases) calcified tissues of mammals. Due to a great chemical similarity with the biological calcified tissues, many calcium orthophosphates possess remarkable biocompatibility and bioactivity. Materials scientists use this property extensively to construct artificial bone grafts that are either entirely made of or only surface-coated with the biologically relevant calcium ortho-phosphates. For example, self-setting hydraulic cements made of calcium orthophosphates are helpful in bone repair, while titanium substitutes covered by a surface layer of calcium orthophosphates are used for hip joint endoprostheses and as tooth substitutes. Porous scaffolds made of calcium orthophosphates are very promising tools for tissue engineering applications. In addition, technical grade calcium orthophosphates are very popular mineral fertilizers. Thus ere calcium orthophosphates are of great significance for humankind and, in this paper, an overview on the current knowledge on this subject is provided.

Inhibitory effect of calcium on non-heme iron absorption may be related to translocation of DMT-1 at the apical membrane of enterocytes.

PubMed

Thompson, Ben A V; Sharp, Paul A; Elliott, Ruan; Fairweather-Tait, Susan J

2010-07-28

Many studies show that calcium reduces iron absorption from single meals, but the underlying mechanism is not known. We tested the hypothesis that calcium alters the expression and/or functionality of iron transport proteins. Differentiated Caco-2 cells were treated with ferric ammonium citrate and calcium chloride, and ferritin, DMT-1, and ferroportin were quantified in whole-cell lysate and cell-membrane fractions. Calcium attenuated the iron-induced increase in cell ferritin levels in a dose-dependent manner; a significant decrease was seen at calcium concentrations of 1.25 and 2.5 mM but was only evident after a 16-24 h incubation period. Calcium and iron treatments decreased DMT-1 protein in Caco-2 cell membranes, although total DMT-1 in whole cell lysates was unchanged by either iron or calcium. No change was seen in ferroportin expression. Our data suggest that calcium reduces iron bioavailability by decreasing DMT-1 expression at the apical cell membrane, thereby downregulating iron transport into the cell.

Activity-dependent gating of calcium spikes by A-type K+ channels controls climbing fiber signaling in Purkinje cell dendrites.

PubMed

Otsu, Yo; Marcaggi, Païkan; Feltz, Anne; Isope, Philippe; Kollo, Mihaly; Nusser, Zoltan; Mathieu, Benjamin; Kano, Masanobu; Tsujita, Mika; Sakimura, Kenji; Dieudonné, Stéphane

2014-10-01

In cerebellar Purkinje cell dendrites, heterosynaptic calcium signaling induced by the proximal climbing fiber (CF) input controls plasticity at distal parallel fiber (PF) synapses. The substrate and regulation of this long-range dendritic calcium signaling are poorly understood. Using high-speed calcium imaging, we examine the role of active dendritic conductances. Under basal conditions, CF stimulation evokes T-type calcium signaling displaying sharp proximodistal decrement. Combined mGluR1 receptor activation and depolarization, two activity-dependent signals, unlock P/Q calcium spikes initiation and propagation, mediating efficient CF signaling at distal sites. These spikes are initiated in proximal smooth dendrites, independently from somatic sodium action potentials, and evoke high-frequency bursts of all-or-none fast-rising calcium transients in PF spines. Gradual calcium spike burst unlocking arises from increasing inactivation of mGluR1-modulated low-threshold A-type potassium channels located in distal dendrites. Evidence for graded activity-dependent CF calcium signaling at PF synapses refines current views on cerebellar supervised learning rules. Copyright © 2014 Elsevier Inc. All rights reserved.

Oocyte cryopreservation and in vitro culture affect calcium signalling during human fertilization.

PubMed

Nikiforaki, D; Vanden Meerschaut, F; Qian, C; De Croo, I; Lu, Y; Deroo, T; Van den Abbeel, E; Heindryckx, B; De Sutter, P

2014-01-01

What are the precise patterns of calcium oscillations during the fertilization of human oocytes matured either in vivo or in vitro or aged in vitro and what is the effect of cryopreservation? Human oocytes matured in vivo exhibit a specific pattern of calcium oscillations, which is affected by in vitro maturation, in vitro ageing and cryopreservation. Oscillations in cytoplasmic calcium concentration are crucial for oocyte activation and further embryonic development. While several studies have described in detail the calcium oscillation pattern during fertilization in animal models, studies with human oocytes are scarce. This was a laboratory-based study using human MII oocytes matured in vivo or in vitro either fresh or after cryopreservation with slow freezing or vitrification. Altogether, 205 human oocytes were included in the analysis. In vivo and in vitro matured human oocytes were used for this research either fresh or following vitrification/warming (V/W) and slow freezing/thawing (F/T). Human oocytes were obtained following written informed consent from patients undergoing ovarian hyperstimulation. For the calcium pattern analysis, oocytes were loaded with the ratiometric calcium indicator fluorescent dye Fura-2. Following ICSI using sperm from a single donor, intracellular calcium was measured for 16 h at 37°C under 6% CO(2). The calcium oscillation parameters were calculated for all intact oocytes that showed calcium oscillations and were analyzed using the Mann-Whitney U-test. Human in vivo MII oocytes display a specific pattern of calcium oscillations following ICSI. This pattern is significantly affected by in vitro ageing, with the calcium oscillations occurring over a longer period of time and with a lower frequency, shorter duration and higher amplitude (P < 0.05). In vitro matured oocytes from the GV and MI stage exhibit a different pattern of calcium oscillations with calcium transients being of lower frequency and shorter duration compared with in vivo matured MII. In MI oocytes that reached the MII stage within 3 h the calcium oscillations additionally appear over a longer period of time (P < 0.05). In vivo MII oocytes show a different calcium oscillation pattern following V/W with calcium oscillations occurring over a longer period of time, with a higher amplitude and a lower frequency (P < 0.05). In vitro matured oocytes, either from the GV or the MI stage, also display an altered pattern of calcium oscillations after V/W and the parameters that were similarly affected in all these oocyte groups are the frequency and the amplitude of the calcium transients. Slow freezing/thawing differentially affects the calcium oscillation pattern of in vitro matured and in vitro aged oocytes. The relationship between a specific pattern of calcium oscillations and subsequent human embryonic development could not be evaluated since the calcium indicator used and the high-intensity excitation light impair development. Furthermore, all oocytes were derived from stimulated cycles and immature oocytes were denuded prior to in vitro maturation. Our data show for the first time how calcium signalling during human fertilization is affected by oocyte in vitro maturation, in vitro ageing as well as V/W and slow freezing/thawing. The analysis of calcium oscillations could be used as an oocyte quality indicator to evaluate in vitro culture and cryopreservation techniques of human oocytes. This work was supported by a clinical research mandate from the Flemish Foundation of Scientific Research (FWO-Vlaanderen, FWO09/ASP/063) to F.V.M, a fundamental clinical research mandate from the FWO-Vlaanderen (FWO05/FKM/001) to P.D.S and a Ghent University grant (KAN-BOF E/01321/01) to B.H. The authors have no conflict of interest to declare.

Mitochondrial Calcium Dysregulation Contributes to Dendrite Degeneration Mediated by PD/LBD-Associated LRRK2 Mutants.

PubMed

Verma, Manish; Callio, Jason; Otero, P Anthony; Sekler, Israel; Wills, Zachary P; Chu, Charleen T

2017-11-15

Mutations in leucine-rich repeat kinase 2 (LRRK2) contribute to development of late-onset familial Parkinson's disease (PD), with clinical features of motor and cognitive dysfunction indistinguishable from sporadic PD. Calcium dysregulation plays an important role in PD pathogenesis, but the mechanisms of neurodegeneration remain unclear. Recent reports indicate enhanced excitatory neurotransmission in cortical neurons expressing mutant LRRK2, which occurs before the well-characterized phenotype of dendritic shortening. As mitochondria play a major role in the rapid buffering of cytosolic calcium, we hypothesized that altered mitochondrial calcium handling contributes to dendritic retraction elicited by the LRRK2-G2019S and -R1441C mutations. In primary mouse cortical neurons, we observed increased depolarization-induced mitochondrial calcium uptake. We found that expression of mutant LRRK2 elicited transcriptional upregulation of the mitochondrial calcium uniporter (MCU) and the mitochondrial calcium uptake 1 protein (MICU1) with no change in levels of the mitochondrial calcium antiporter NCLX. Elevated MCU and MICU1 were also observed in LRRK2-mutated patient fibroblasts, along with increased mitochondrial calcium uptake, and in postmortem brains of sporadic PD/PDD patients of both sexes. Transcriptional upregulation of MCU and MICU1 was caused by activation of the ERK1/2 (MAPK3/1) pathway. Inhibiting ERK1/2 conferred protection against mutant LRRK2-induced neurite shortening. Pharmacological inhibitors or RNAi knockdown of MCU attenuated mitochondrial calcium uptake and dendritic/neuritic shortening elicited by mutant LRRK2, whereas expression of a constitutively active mutant of NCLX that enhances calcium export from mitochondria was neuroprotective. These data suggest that an increased susceptibility to mitochondrial calcium dysregulation contributes to dendritic injury in mutant LRRK2 pathogenesis. SIGNIFICANCE STATEMENT Cognitive dysfunction and dementia are common features of Parkinson's disease (PD), causing significant disability. Mutations in LRRK2 represent the most common known genetic cause of PD. We found that PD-linked LRRK2 mutations increased dendritic and mitochondrial calcium uptake in cortical neurons and familial PD patient fibroblasts, accompanied by increased expression of the mitochondrial calcium transporter MCU. Blocking the ERK1/2-dependent upregulation of MCU conferred protection against mutant LRRK2-elicited dendrite shortening, as did inhibiting MCU-mediated calcium import. Conversely, stimulating the export of calcium from mitochondria was also neuroprotective. These results implicate increased susceptibility to mitochondrial calcium overload in LRRK2-driven neurodegeneration, and suggest possible interventions that may slow the progression of cognitive dysfunction in PD. Copyright © 2017 the authors 0270-6474/17/3711152-15$15.00/0.

[The peculiarities of calcium metabolism regulation in different periods of growth and development].

PubMed

Moĭsa, S S; Nozdrachev, A D

2014-01-01

The review contains literature data about calcium metabolism regulation in different periods of growth and development. The analyses of retrospective and current sources of information about the regulation of calcium homeostasis under the theory of functional systems, the regulation of calcium metabolism in prenatal and postnatal periods of the development, the significance of calcium metabolism disturbances in the development of pathological conditions were showed.

Impact of calcium and vitamin D insufficiencies on serum parathyroid hormone and bone mineral density: analysis of the 4th & 5th Korean National Health and Nutrition Examination Survey

USDA-ARS?s Scientific Manuscript database

The relative contributions of calcium and vitamin D to calcium metabolism and bone mineral density (BMD) have been examined previously, but not in a population with very low calcium intake. To determine the relative importance of dietary calcium intake and serum 25-hydroxyvitamin D [25(OH)D] concent...

Directionality in drug action on sodium-calcium exchange.

PubMed

Noble, D; Blaustein, M P

2007-03-01

In pathological conditions, the exchanger may generate deleterious calcium entry. A drug that inhibited calcium entry, while still allowing transport of calcium out of the cell would then seem attractive. In fact, this is impossible for thermodynamic reasons. Inhibitors may appear to be more effective when the exchanger is operating in net calcium entry mode than in calcium exit mode. This is, however, always attributable to differences in conditions because there is strong internal sodium dependence of drug action on the exchanger. When the exchanger is operating near equilibrium, drug action is found to be equally effective in both directions.

Calcium revisited, part III: effect of dietary calcium on BMD and fracture risk

PubMed Central

Burckhardt, Peter

2015-01-01

Food can be an excellent source of calcium. Dietary calcium is in general as well absorbed as calcium supplements, and exerts the same effects on bone. The main sources are dairy products, but also some vegetables and fruits contain considerable amounts of calcium. Mineral water can serve as a supplement. Cross-sectional, longitudinal and some interventional trials have shown positive effects on bone metabolism, bone density and bone loss. But the effect on fracture incidence is less certain, and that of milk, the most studied dairy product, still unproven. PMID:26331006

Voltage-Gated Calcium Channels

NASA Astrophysics Data System (ADS)

Zamponi, Gerald Werner

Voltage Gated Calcium Channels is the first comprehensive book in the calcium channel field, encompassing over thirty years of progress towards our understanding of calcium channel structure, function, regulation, physiology, pharmacology, and genetics. This book balances contributions from many of the leading authorities in the calcium channel field with fresh perspectives from risings stars in the area, taking into account the most recent literature and concepts. This is the only all-encompassing calcium channel book currently available, and is an essential resource for academic researchers at all levels in the areas neuroscience, biophysics, and cardiovascular sciences, as well as to researchers in the drug discovery area.

Role of calcium in phosphoinositide metabolism and inhibition of norepinephrine transport into synaptic vesicles by amphetamine analogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knepper, S.M.

1985-01-01

Norepinephrine-(NE) and calcium ionophore A23187-stimulated phosphoinositide (PIn) metabolism in rat brain slices was studied under varying calcium conditions. Tissue was labelled with /sup 3/H-myo-inositol and /sup 3/H-inositol phosphates (IPn), products of PIn metabolism were measured. In the absence of media calcium the response to NE was decreased while that to A23187 was little affected A23187 can release calcium from intracellular stores. Basal and stimulated accumulation of /sup 3/H-IPn was reversibly antagonized with EGTA by addition of calcium. Using calcium buffers, approximately 10/sup -7/ M free calcium was required to support hydrolysis. Free intracellular calcium is maintained at approximately this level.more » Thus calcium is required for PIn hydrolysis but appears to play a permissive role, basal levels being sufficient to support metabolism. Conformationally-defined (rigid) and -restricted (semi-rigid) analogs of the most stable conformations of amphetamine, antiperiplanar (exo) and gauche (endo), were utilized to probe the conformational requirements of vesicular NE transport. Analogs tested were 2-aminotetralin (2AT), 3-methyltetrahydroisoquinoline, anti- and syn-9-aminobenzobicyclo(2.2.1)heptene, and endo and exo conformers of 2-aminobenzobicyclo(2.2.1)heptene and 2-aminobenzobicyclo(2.2.2)octene.« less

Effects of Hydration and Calcium Supplementation on Urine Calcium Concentration in Healthy Postmenopausal Women.

PubMed

Harris, Susan S; Dawson-Hughes, Bess

2015-01-01

The aim of this study was to determine whether calcium supplementation, compared with placebo, increases urine calcium concentrations to levels indicative of increased renal stone risk, and the role that fluid intake, as indicated by urine volume, may play in mitigating this risk. This is a secondary analysis of data from a randomized placebo-controlled trial of 500 mg/d calcium supplementation to prevent bone loss. Subjects were 240 white postmenopausal women age 40 to 70 years in good general health. Effects of supplementation on 1-year changes in 24h urine calcium concentration and urine volume were examined. Both treatment group and urine volume were strong independent predictors of urine calcium concentration (p < 0.001). Among subjects with urine volume under 2 L/24 h, more than half of placebo subjects were at lowest risk for renal stones compared with less than 35% of calcium-supplemented subjects. Among those with higher urine volumes, all placebo subjects and more than 80% of calcium supplemented subjects were at lowest risk. The increased risk of renal stones with calcium supplement use may be largely eliminated with adequate fluid intake, but older adults may not spontaneously consume adequate fluids to minimize this risk and should be counseled to do so.

Calcium overloading in traumatic axonal injury by lateral head rotation: a morphological evidence in rat model.

PubMed

He, Xiao-Sheng; Xiang, Zhang; Zhou, Fei; Fu, Luo-An; Shuang, Wang

2004-05-01

The study investigated morphologically axonal calcium overloading and its relationship with axonal structural changes. Twelve SD rats were divided into an injury and a sham group. The rat model of traumatic axonal injury (TAI) by lateral head rotation was produced. The oxalate-pyroantimonate technique for calcium localization was used to process the rat's medulla oblongata tissues with thin sections observed electron-microscopically for axonal structure and calcium precipitates on it. The axonal damage in medulla oblongata appeared at 2 h post-injury, gradually became diffuse and severe, and continued to exist at 24 hours. At 2 hours, calcium precipitates were deposited on separated lamellae and axolemma, but were rarely distributed in the axoplasm. At 6 hours, calcium precipitates occurred on separated lamellae and axolemma in much higher density, but on axoplasm in extremely small amounts. Some axons, though lacking structural changes of the myelin sheath, sequestered plenty of calcium deposits on their swollen mitochondria. At 24 hours, damaged axons presented with much more severe lamellae separation and calcium deposits. Axonal calcium overloading developed in rat TAI model using lateral head rotation. This was significantly related to structural damage in the axons. These findings suggest the feasibility of using calcium antagonists in cope the management of human DAI in its very early stage.

Urine risk factors in children with calcium kidney stones and their siblings

PubMed Central

Bergsland, Kristin J.; Coe, Fredric L.; White, Mark D.; Erhard, Michael J.; DeFoor, William R.; Mahan, John D.; Schwaderer, Andrew L.; Asplin, John R.

2012-01-01

Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone forming children, we compared chemical measurements and the crystallization properties of 24-hour urine collections from 129 stone formers matched to 105 non-stone forming siblings and 183 normal, healthy children with no family history of stones; all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones. PMID:22358148

Restricting calcium currents is required for correct fiber type specification in skeletal muscle

PubMed Central

Sultana, Nasreen; Dienes, Beatrix; Benedetti, Ariane; Tuluc, Petronel; Szentesi, Peter; Sztretye, Monika; Rainer, Johannes; Hess, Michael W.; Schwarzer, Christoph; Obermair, Gerald J.; Csernoch, Laszlo

2016-01-01

ABSTRACT Skeletal muscle excitation-contraction (EC) coupling is independent of calcium influx. In fact, alternative splicing of the voltage-gated calcium channel CaV1.1 actively suppresses calcium currents in mature muscle. Whether this is necessary for normal development and function of muscle is not known. However, splicing defects that cause aberrant expression of the calcium-conducting developmental CaV1.1e splice variant correlate with muscle weakness in myotonic dystrophy. Here, we deleted CaV1.1 (Cacna1s) exon 29 in mice. These mice displayed normal overall motor performance, although grip force and voluntary running were reduced. Continued expression of the developmental CaV1.1e splice variant in adult mice caused increased calcium influx during EC coupling, altered calcium homeostasis, and spontaneous calcium sparklets in isolated muscle fibers. Contractile force was reduced and endurance enhanced. Key regulators of fiber type specification were dysregulated and the fiber type composition was shifted toward slower fibers. However, oxidative enzyme activity and mitochondrial content declined. These findings indicate that limiting calcium influx during skeletal muscle EC coupling is important for the secondary function of the calcium signal in the activity-dependent regulation of fiber type composition and to prevent muscle disease. PMID:26965373

Urine risk factors in children with calcium kidney stones and their siblings.

PubMed

Bergsland, Kristin J; Coe, Fredric L; White, Mark D; Erhard, Michael J; DeFoor, William R; Mahan, John D; Schwaderer, Andrew L; Asplin, John R

2012-06-01

Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence, treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone-forming children, we compared chemical measurements and the crystallization properties of 24-h urine collections from 129 stone formers matched to 105 non-stone-forming siblings and 183 normal, healthy children with no family history of stones, all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH, and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones.

Novel calcium recognition constructions in proteins: Calcium blade and EF-hand zone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denesyuk, Alexander I., E-mail: adenesyu@abo.fi; Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino 142290; Permyakov, Sergei E.

Metal ions can regulate various cell processes being first, second or third messengers, and some of them, especially transition metal ions, take part in catalysis in many enzymes. As an intracellular ion, Ca{sup 2+} is involved in many cellular functions from fertilization and contraction, cell differentiation and proliferation, to apoptosis and cancer. Here, we have identified and described two novel calcium recognition environments in proteins: the calcium blade zone and the EF-hand zone, common to 12 and 8 different protein families, respectively. Each of the two environments contains three distinct structural elements: (a) the well-known characteristic Dx[DN]xDG motif; (b) anmore » adjacent structurally identical segment, which binds metal ion in the same way between the calcium blade zone and the EF-hand zone; and (c) the following structurally variable segment, which distinguishes the calcium blade zone from the EF-hand zone. Both zones have sequence insertions between the last residue of the zone and calcium-binding residues in positions V or VI. The long insertion often connects the active and the calcium-binding sites in proteins. Using the structurally identical segments as an anchor, we were able to construct the classical calmodulin type EF-hand calcium-binding site out of two different calcium-binding motifs from two unrelated proteins.« less

Action of cholecystokinin and cholinergic agents on calcium transport in isolated pancreatic acinar cells.

PubMed Central

Gardner, J D; Conlon, T P; Kleveman, H L; Adams, T D; Ondetti, M A

1975-01-01

COOH-terminal octapeptide of cholecystokinin (CCK-octapeptide) and the cholinergic agent carbamylcholine each produced a fourfold stimulation of calcium outflux in guinea pig isolated pancreatic acinar cells. Neither agent altered calcium influx. Stimulation of calcium outflux was rapid and specific, was abolished by reducing the incubation temperature to 4 degrees C, and was a saturable function of the secretagogue concentration. The concentrations of CCK-octapeptide and carbamylcholine that produced half-maximal stimulation of calcium outflux were 3.1 x 10(-10) M and 4.9 x 10(-5) M, respectively. The cholinergic antagonist antropine competitively inhibited carbamylcholine stimulation of calcium outflux but did not alter stimulation produced by CCK-octapeptide. Stimulation of calcium outflux by maximal concentrations of carbamycholine plus CCK-octapeptide was the same as that produced by a maximal concentration of either agent alone.Calcium outflux became refractory to stimulation by secretagogues, and incubation with either CCK-ostapeptide or carbamylcholine produced a refractoriness to both agents. The relative potencies with CCK and its related fragments stimulated calcium outflux were CCK-octapeptide greater than heptapeptide greater than CCK greater than hexapeptide = gastrin. Secretin, glucagon, and vasoactive intestinal peptide, at concentrations as high as 10(-5) M, failed to alter calcium outflux and did not affect stimulation by CCK-octapeptide or by carbamycholine. Images PMID:1150877

Efficacy of Mixtures of Magnesium, Citrate and Phytate as Calcium Oxalate Crystallization Inhibitors in Urine.

PubMed

Grases, Felix; Rodriguez, Adrian; Costa-Bauza, Antonia

2015-09-01

The main aim of the current study was to evaluate the effectiveness of mixtures of magnesium, citrate and phytate as calcium oxalate crystallization inhibitors. A turbidimetric assay in synthetic urine was performed to obtain induction times for calcium oxalate crystallization in the absence and presence of different mixtures of inhibitors. The morphology of calcium oxalate crystals in the absence or presence of inhibitors and mixtures of the inhibitors was evaluated in 2 crystallization experiments at low and high calcium oxalate supersaturation. The crystals formed were examined using scanning electron microscopy. Examination of crystallization induction times revealed clear inhibitory effects of magnesium, citrate and phytate on calcium oxalate crystallization, supporting usefulness in the treatment and prevention of calcium oxalate nephrolithiasis. Significant synergistic effects between magnesium and phytate were observed. Scanning electron microscopy images revealed that phytate is a powerful crystal growth inhibitor of calcium oxalate, totally preventing the formation of trihydrate and monohydrate. In addition to crystallization inhibition capacity, citrate and magnesium avoided calcium oxalate crystallization by decreasing its supersaturation. The synergistic effect between magnesium and phytate on calcium oxalate crystallization suggests that a combination of these 2 compounds may be highly useful as antilithiasis therapy. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Aspects of calcium oxalate crystallization: theory, in vitro studies, and in vivo implementation.

PubMed

Rodgers, A

1999-11-01

There are three main approaches to urolithiasis research: theory, basic science, and clinical implementation. Although each approach has yielded meaningful results, there does not appear to be complete synergy between them. This article examines these approaches as they pertain to urinary calcium oxalate crystallization processes. Theoretical calculations were performed to examine the role of oxalate concentration on calcium oxalate supersaturation. The effects of magnesium, citrate, and combinations thereof on calcium oxalate crystallization kinetics were examined in a mixed suspension, mixed product removal crystallizer. Finally, male volunteers were given supplements of calcium alone and binary combinations of calcium, magnesium, and citrate to investigate their effects on the urinary supersaturation of calcium oxalate. Calculations showed that oxalate is 23 times more potent than calcium in its effect on the supersaturation of calcium oxalate. In the in vitro experiments, magnesium and citrate reduced the growth and nucleation kinetics as well as the supersaturation. In combination, these two components were more effective than the individual components in reducing the growth rate and the supersaturation. All of the supplements favorably altered the kinetic and thermodynamic risk factors. Calcium was the most effective in reducing the urinary excretion of oxalate. Articulation of these three approaches is essential for the meaningful investigation and understanding of urolithiasis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Recker, R.R.

Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/-more » 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement.« less

Growth control in colon epithelial cells: gadolinium enhances calcium-mediated growth regulation.

PubMed

Attili, Durga; Jenkins, Brian; Aslam, Muhammad Nadeem; Dame, Michael K; Varani, James

2012-12-01

Gadolinium, a member of the lanthanoid family of transition metals, interacts with calcium-binding sites on proteins and other biological molecules. The overall goal of the present investigation was to determine if gadolinium could enhance calcium-induced epithelial cell growth inhibition in the colon. Gadolinium at concentrations as low as 1-5 μM combined with calcium inhibits proliferation of human colonic epithelial cells more effectively than calcium alone. Gadolinium had no detectable effect on calcium-induced differentiation in the same cells based on change in cell morphology, induction of E-cadherin synthesis, and translocation of E-cadherin from the cytosol to the cell surface. When the colon epithelial cells were treated with gadolinium and then exposed to increased calcium concentrations, movement of extracellular calcium into the cell was suppressed. In contrast, gadolinium treatment had no effect on ionomycin-induced release of stored intracellular calcium into the cytoplasm. Whether these in vitro observations can be translated into an approach for reducing abnormal proliferation in the colonic mucosa (including polyp formation) is not known. These results do, however, provide an explanation for our recent findings that a multi-mineral supplement containing all of the naturally occurring lanthanoid metals including gadolinium are more effective than calcium alone in preventing colon polyp formation in mice on a high-fat diet.

Inhibition of parathyroid hormone release by maitotoxin, a calcium channel activator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzpatrick, L.A.; Yasumoto, T.; Aurbach, G.D.

1989-01-01

Maitotoxin, a toxin derived from a marine dinoflagellate, is a potent activator of voltage-sensitive calcium channels. To further test the hypothesis that inhibition of PTH secretion by calcium is mediated via a calcium channel we studied the effect of maitotoxin on dispersed bovine parathyroid cells. Maitotoxin inhibited PTH release in a dose-dependent fashion, and inhibition was maximal at 1 ng/ml. Chelation of extracellular calcium by EGTA blocked the inhibition of PTH by maitotoxin. Maitotoxin enhanced the effects of the dihydropyridine calcium channel agonist (+)202-791 and increased the rate of radiocalcium uptake in parathyroid cells. Pertussis toxin, which ADP-ribosylates and inactivatesmore » a guanine nucleotide regulatory protein that interacts with calcium channels in the parathyroid cell, did not affect the inhibition of PTH secretion by maitotoxin. Maitotoxin, by its action on calcium channels allows entry of extracellular calcium and inhibits PTH release. Our results suggest that calcium channels are involved in the release of PTH. Inhibition of PTH release by maitotoxin is not sensitive to pertussis toxin, suggesting that maitotoxin may act distal to the site interacting with a guanine nucleotide regulatory protein, or maitotoxin could interact with other ions or second messengers to inhibit PTH release.« less

The role of calcium in osteoporosis.

PubMed

Arnaud, C D; Sanchez, S D

1990-01-01

Calcium requirements may vary throughout the lifespan. During the growth years and up to age 25-30, it is important to maximize dietary intake of calcium to maintain positive calcium balance and achieve peak bone mass, thereby possibly decreasing the risk of fracture when bone is subsequently lost. The RDA for age 10-25 is 1200 mg/day. Calcium intake need not be greater than 800 mg/day during the relatively short period of time between the end of bone building and the onset of bone loss (30 to 40 years old). Starting at age 40-45, both men and women lose bone slowly, but women lose bone more rapidly around the menopause and for about 10 years after. Intestinal calcium absorption and the ability to adapt to low calcium diets are impaired in many postmenopausal women and elderly persons owing to a suspected functional or absolute decrease in the ability of the kidney to produce 1,25(OH)2D3. The bones then become more and more a source of calcium to maintain critical extracellular fluid calcium levels. Available evidence suggests that the impairments of intestinal calcium absorption observed during the menopause and aging can be overcome only by inordinately large calcium intakes (1500 to 2500 mg/day). Since this amount is difficult to derive from the diet, can cause constipation, and may not prevent trabecular bone loss, it should not be used as a substitute for sex hormone replacement. Women taking estrogen replacement should be provided the RDA for calcium of 800 mg/day at a minimum. Those who cannot or will not take estrogen should be asked to ingest at least 1000 to 1500 mg/day of calcium to delay cortical bone loss and prevent secondary hyperparathyroidism. It should be emphasized that up to 2000 mg/day of calcium is safe in teenaged children and adults. Excessive dietary intake of protein and fiber may induce significant negative calcium balance and thus increase dietary calcium requirements. It is also possible that excessive intakes of phosphate could have a deleterious effect on calcium balance in populations whose need for calcium is great (e.g. growing children) or whose ability to produce 1,25(OH)2D3 is impaired (e.g. the elderly). Moderation in the intake of these nutrients is urged. Generally, the strongest risk factors for osteoporosis are uncontrollable (e.g. sex, age, and race) or less controllable (e.g. disease and medications). However, several factors such as diet, physical activity, cigarette smoking, and alcohol use are lifestyle related and can be modified to help reduce the risk of osteoporosis.

Proteomic Analysis of Calcium Effects on Soybean Root Tip under Flooding and Drought Stresses.

PubMed

Wang, Xin; Komatsu, Setsuko

2017-08-01

Flooding and drought are disadvantageous environmental conditions that induce cytosolic calcium in soybean. To explore the effects of flooding- and drought-induced increases in calcium, a gel-free/label-free proteomic analysis was performed. Cytosolic calcium was decreased by blocking calcium channels in the endoplasmic reticulum (ER) and plasma membrane under both stresses. Calnexin, protein disulfide isomerase, heat shock proteins and thioredoxin were predominantly affected as the ER proteins in response to calcium, and ER-associated degradation-related proteins of HCP-like superfamily protein were up-regulated under stress exposure and then down-regulated. Glycolysis, fermentation, the tricarboxylic acid cycle and amino acid metabolism were mainly induced as the types of cellular metabolism in response to calcium under both stresses. Pyruvate decarboxylase was increased and decreased under flooding and drought, respectively, and was further decreased by the reduction of cytosolic calcium; however, it was recovered by exogenous calcium under both stresses. Furthermore, pyruvate decarboxylase activity was increased under flooding, but decreased under drought. These results suggest that calcium is involved in protein folding in the ER, and ER-associated degradation might alleviate ER stress during the early stage of both stresses. Furthermore, calcium appears to modify energy metabolism, and pyruvate decarboxylase may be a key enzyme in this process under flooding and drought. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Sodium entry through endothelial store-operated calcium entry channels: regulation by Orai1

PubMed Central

Xu, Ningyong; Cioffi, Donna L.; Alexeyev, Mikhail; Rich, Thomas C.

2014-01-01

Orai1 interacts with transient receptor potential protein of the canonical subfamily (TRPC4) and contributes to calcium selectivity of the endothelial cell store-operated calcium entry current (ISOC). Orai1 silencing increases sodium permeability and decreases membrane-associated calcium, although it is not known whether Orai1 is an important determinant of cytosolic sodium transitions. We test the hypothesis that, upon activation of store-operated calcium entry channels, Orai1 is a critical determinant of cytosolic sodium transitions. Activation of store-operated calcium entry channels transiently increased cytosolic calcium and sodium, characteristic of release from an intracellular store. The sodium response occurred more abruptly and returned to baseline more rapidly than did the transient calcium rise. Extracellular choline substitution for sodium did not inhibit the response, although 2-aminoethoxydiphenyl borate and YM-58483 reduced it by ∼50%. After this transient response, cytosolic sodium continued to increase due to influx through activated store-operated calcium entry channels. The magnitude of this sustained increase in cytosolic sodium was greater when experiments were conducted in low extracellular calcium and when Orai1 expression was silenced; these two interventions were not additive, suggesting a common mechanism. 2-Aminoethoxydiphenyl borate and YM-58483 inhibited the sustained increase in cytosolic sodium, only in the presence of Orai1. These studies demonstrate that sodium permeates activated store-operated calcium entry channels, resulting in an increase in cytosolic sodium; the magnitude of this response is determined by Orai1. PMID:25428882

Crystal structure of metagenomic β-xylosidase/ α-l-arabinofuranosidase activated by calcium.

PubMed

Matsuzawa, Tomohiko; Kaneko, Satoshi; Kishine, Naomi; Fujimoto, Zui; Yaoi, Katsuro

2017-09-01

The crystal structure of metagenomic β-xylosidase/α-l-arabinofuranosidase CoXyl43, activated by calcium ions, was determined in its apo and complexed forms with xylotriose or l-arabinose in the presence and absence of calcium. The presence of calcium ions dramatically increases the kcat of CoXyl43 for p-nitrophenyl β-d-xylopyranoside and reduces the Michaelis constant for p-nitrophenyl α-l-arabinofuranoside. CoXyl43 consists of a single catalytic domain comprised of a five-bladed β-propeller. In the presence of calcium, a single calcium ion was observed at the centre of this catalytic domain, behind the catalytic pocket. In the absence of calcium, the calcium ion was replaced with one sodium ion and one water molecule, and the positions of these cations were shifted by 1.3 Å. The histidine-319 side chain, which coordinates to the 2-hydroxyl oxygen atom of the bound xylose molecule in the catalytic pocket, also coordinates to the calcium ion, but not to the sodium ion. The calcium-dependent increase in activity appears to be caused by the structural change in the catalytic pocket induced by the tightly bound calcium ion and coordinating water molecules, and by the protonation state of glutamic acid-268, the catalytic acid of the enzyme. Our findings further elucidate the complex relationship between metal ions and glycosidases. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Metabotropic and ionotropic glutamate receptors regulate calcium channel currents in salamander retinal ganglion cells

PubMed Central

Shen, Wen; Slaughter, Malcolm M

1998-01-01

Glutamate suppressed high-voltage-activated barium currents (IBa,HVA) in tiger salamander retinal ganglion cells. Both ionotropic (iGluR) and metabotropic (mGluR) receptors contributed to this calcium channel inhibition. Trans-ACPD (1-aminocyclopentane-trans-1S,3R-dicarboxylic acid), a broad-spectrum metabotropic glutamate receptor agonist, suppressed a dihydropyridine-sensitive barium current. Kainate, an ionotropic glutamate receptor agonist, reduced an ω-conotoxin GVIA-sensitive current. The relative effectiveness of selective agonists indicated that the predominant metabotropic receptor was the L-2-amino-4-phosphonobutyrate (l-AP4)-sensitive, group III receptor. This receptor reversed the action of forskolin, but this was not responsible for calcium channel suppression. l-AP4 raised internal calcium concentration. Antagonists of phospholipase C, inositol trisphosphate (IP3) receptors and ryanodine receptors inhibited the action of metabotropic agonists, indicating that group III receptor transduction was linked to this pathway. The action of kainate was partially suppressed by BAPTA, by calmodulin antagonists and by blockers of calmodulin-dependent phosphatase. Suppression by kainate of the calcium channel current was more rapid when calcium was the charge carrier, instead of barium. The results indicate that calcium influx through kainate-sensitive glutamate receptors can activate calmodulin, which stimulates phosphatases that may directly suppress voltage-sensitive calcium channels. Thus, ionotropic and metabotropic glutamate receptors inhibit distinct calcium channels. They could act synergistically, since both increase internal calcium. These pathways provide negative feedback that can reduce calcium influx when ganglion cells are depolarized. PMID:9660896

Calcium dynamics in cardiac excitatory and non-excitatory cells and the role of gap junction.

PubMed

Das, Phonindra Nath; Mehrotra, Parul; Mishra, Aseem; Bairagi, Nandadulal; Chatterjee, Samrat

2017-07-01

Calcium ions aid in the generation of action potential in myocytes and are responsible for the excitation-contraction coupling of heart. The heart muscle has specialized patches of cells, called excitatory cells (EC) such as the Sino-atrial node cells capable of auto-generation of action potential and cells which receive signals from the excitatory cells, called non-excitatory cells (NEC) such as cells of the ventricular and auricular walls. In order to understand cardiac calcium homeostasis, it is, therefore, important to study the calcium dynamics taking into account both types of cardiac cells. Here we have developed a model to capture the calcium dynamics in excitatory and non-excitatory cells taking into consideration the gap junction mediated calcium ion transfer from excitatory cell to non-excitatory cell. Our study revealed that the gap junctional coupling between excitatory and non-excitatory cells plays important role in the calcium dynamics. It is observed that any reduction in the functioning of gap junction may result in abnormal calcium oscillations in NEC, even when the calcium dynamics is normal in EC cell. Sensitivity of gap junction is observed to be independent of the pacing rate and hence a careful monitoring is required to maintain normal cardiomyocyte condition. It also highlights that sarcoplasmic reticulum may not be always able to control the amount of cytoplasmic calcium under the condition of calcium overload. Copyright © 2017 Elsevier Inc. All rights reserved.

Skin Barrier and Calcium.

PubMed

Lee, Sang Eun; Lee, Seung Hun

2018-06-01

Epidermal barrier formation and the maintenance of barrier homeostasis are essential to protect us from the external environments and organisms. Moreover, impaired keratinocytes differentiation and dysfunctional skin barrier can be the primary causes or aggravating factors for many inflammatory skin diseases including atopic dermatitis and psoriasis. Therefore, understanding the regulation mechanisms of keratinocytes differentiation and skin barrier homeostasis is important to understand many skin diseases and establish an effective treatment strategy. Calcium ions (Ca 2+ ) and their concentration gradient in the epidermis are essential in regulating many skin functions, including keratinocyte differentiation, skin barrier formation, and permeability barrier homeostasis. Recent studies have suggested that the intracellular Ca 2+ stores such as the endoplasmic reticulum (ER) are the major components that form the epidermal calcium gradient and the ER calcium homeostasis is crucial for regulating keratinocytes differentiation, intercellular junction formation, antimicrobial barrier, and permeability barrier homeostasis. Thus, both Ca 2+ release from intracellular stores, such as the ER and Ca 2+ influx mechanisms are important in skin barrier. In addition, growing evidences identified the functional existence and the role of many types of calcium channels which mediate calcium flux in keratinocytes. In this review, the origin of epidermal calcium gradient and their role in the formation and regulation of skin barrier are focused. We also focus on the role of ER calcium homeostasis in skin barrier. Furthermore, the distribution and role of epidermal calcium channels, including transient receptor potential channels, store-operated calcium entry channel Orai1, and voltage-gated calcium channels in skin barrier are discussed.

Structural dynamics of the cell nucleus: basis for morphology modulation of nuclear calcium signaling and gene transcription.

PubMed

Queisser, Gillian; Wiegert, Simon; Bading, Hilmar

2011-01-01

Neuronal morphology plays an essential role in signal processing in the brain. Individual neurons can undergo use-dependent changes in their shape and connectivity, which affects how intracellular processes are regulated and how signals are transferred from one cell to another in a neuronal network. Calcium is one of the most important intracellular second messengers regulating cellular morphologies and functions. In neurons, intracellular calcium levels are controlled by ion channels in the plasma membrane such as NMDA receptors (NMDARs), voltage-gated calcium channels (VGCCs) and certain α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as well as by calcium exchange pathways between the cytosol and internal calcium stores including the endoplasmic reticulum and mitochondria. Synaptic activity and the subsequent opening of ligand and/or voltage-gated calcium channels can initiate cytosolic calcium transients which propagate towards the cell soma and enter the nucleus via its nuclear pore complexes (NPCs) embedded in the nuclear envelope. We recently described the discovery that in hippocampal neurons the morphology of the nucleus affects the calcium dynamics within the nucleus. Here we propose that nuclear infoldings determine whether a nucleus functions as an integrator or detector of oscillating calcium signals. We outline possible ties between nuclear mophology and transcriptional activity and discuss the importance of extending the approach to whole cell calcium signal modeling in order to understand synapse-to-nucleus communication in healthy and dysfunctional neurons.

The role of uncoupling protein 3 regulating calcium ion uptake into mitochondria during sarcopenia

NASA Astrophysics Data System (ADS)

Nikawa, Takeshi; Choi, Inho; Haruna, Marie; Hirasaka, Katsuya; Maita Ohno, Ayako; Kondo Teshima, Shigetada

Overloaded mitochondrial calcium concentration contributes to progression of mitochondrial dysfunction in aged muscle, leading to sarcopenia. Uncoupling protein 3 (UCP3) is primarily expressed in the inner membrane of skeletal muscle mitochondria. Recently, it has been reported that UCP3 is associated with calcium uptake into mitochondria. However, the mechanisms by which UCP3 regulates mitochondrial calcium uptake are not well understood. Here we report that UCP3 interacts with HS-1 associated protein X-1 (Hax-1), an anti-apoptotic protein that is localized in mitochondria, which is involved in cellular responses to calcium ion. The hydrophilic sequences within the loop 2, matrix-localized hydrophilic domain of mouse UCP3 are necessary for binding to Hax-1 of the C-terminal domain in adjacent to mitochondrial innermembrane. Interestingly, these proteins interaction occur the calcium-dependent manner. Indeed, overexpression of UCP3 significantly enhanced calcium uptake into mitochondria on Hax-1 endogenously expressing C2C12 myoblasts. In addition, Hax-1 knock-down enhanced calcium uptake into mitochondria on both UCP3 and Hax-1 endogenously expressing C2C12 myotubes, but not myoblasts. Finally, the dissociation of UCP3 and Hax-1 enhances calcium uptake into mitochondria in aged muscle. These studies identify a novel UCP3-Hax-1 complex regulates the influx of calcium ion into mitochondria in muscle. Thus, the efficacy of UCP3-Hax-1 in mitochondrial calcium regulation may provide a novel therapeutic approach against mitochondrial dysfunction-related disease containing sarcopenia.

40 CFR 461.20 - Applicability; description of the calcium subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium subcategory. 461.20 Section 461.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS BATTERY MANUFACTURING POINT SOURCE CATEGORY Calcium Subcategory § 461.20 Applicability; description of the calcium subcategory. This subpart applies to discharges to...

21 CFR 582.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium hexametaphosphate. 582.6203 Section 582.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

40 CFR 415.310 - Applicability; description of the calcium hydroxide production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium hydroxide production subcategory. 415.310 Section 415.310 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Hydroxide Production Subcategory § 415.310 Applicability; description of the calcium hydroxide production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.40 - Applicability; description of the calcium chloride production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium chloride production subcategory. 415.40 Section 415.40 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Chloride Production Subcategory § 415.40 Applicability; description of the calcium chloride production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 461.20 - Applicability; description of the calcium subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium subcategory. 461.20 Section 461.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS BATTERY MANUFACTURING POINT SOURCE CATEGORY Calcium Subcategory § 461.20 Applicability; description of the calcium subcategory. This subpart applies to discharges to...

40 CFR 415.310 - Applicability; description of the calcium hydroxide production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium hydroxide production subcategory. 415.310 Section 415.310 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Hydroxide Production Subcategory § 415.310 Applicability; description of the calcium hydroxide production subcategory. The provisions of this subpart are applicable to discharges...

21 CFR 182.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium hexametaphosphate. 182.6203 Section 182.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

21 CFR 182.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium hexametaphosphate. 182.6203 Section 182.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

21 CFR 582.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium hexametaphosphate. 582.6203 Section 582.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

Calcium Blood Test

MedlinePlus

... Your health care provider may order a calcium test if you have a pre-existing condition that may affect your calcium levels. These include: Kidney disease Thyroid disease Malnutrition Certain types of cancer What happens during a calcium blood test? A health care professional will take a blood ...

40 CFR 415.40 - Applicability; description of the calcium chloride production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium chloride production subcategory. 415.40 Section 415.40 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Chloride Production Subcategory § 415.40 Applicability; description of the calcium chloride production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 461.20 - Applicability; description of the calcium subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium subcategory. 461.20 Section 461.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) BATTERY MANUFACTURING POINT SOURCE CATEGORY Calcium Subcategory § 461.20 Applicability; description of the calcium subcategory. This subpart applies to discharges...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 461.20 - Applicability; description of the calcium subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium subcategory. 461.20 Section 461.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) BATTERY MANUFACTURING POINT SOURCE CATEGORY Calcium Subcategory § 461.20 Applicability; description of the calcium subcategory. This subpart applies to discharges...

40 CFR 415.310 - Applicability; description of the calcium hydroxide production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium hydroxide production subcategory. 415.310 Section 415.310 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Hydroxide Production Subcategory § 415.310 Applicability; description of the calcium hydroxide production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.310 - Applicability; description of the calcium hydroxide production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium hydroxide production subcategory. 415.310 Section 415.310 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Hydroxide Production Subcategory § 415.310 Applicability; description of the calcium hydroxide production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.310 - Applicability; description of the calcium hydroxide production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium hydroxide production subcategory. 415.310 Section 415.310 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Hydroxide Production Subcategory § 415.310 Applicability; description of the calcium hydroxide production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.40 - Applicability; description of the calcium chloride production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium chloride production subcategory. 415.40 Section 415.40 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Chloride Production Subcategory § 415.40 Applicability; description of the calcium chloride production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.40 - Applicability; description of the calcium chloride production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium chloride production subcategory. 415.40 Section 415.40 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Chloride Production Subcategory § 415.40 Applicability; description of the calcium chloride production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 461.20 - Applicability; description of the calcium subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium subcategory. 461.20 Section 461.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) BATTERY MANUFACTURING POINT SOURCE CATEGORY Calcium Subcategory § 461.20 Applicability; description of the calcium subcategory. This subpart applies to discharges...

21 CFR 582.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium hexametaphosphate. 582.6203 Section 582.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

21 CFR 182.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium hexametaphosphate. 182.6203 Section 182.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

21 CFR 582.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium hexametaphosphate. 582.6203 Section 582.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

40 CFR 415.40 - Applicability; description of the calcium chloride production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium chloride production subcategory. 415.40 Section 415.40 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Chloride Production Subcategory § 415.40 Applicability; description of the calcium chloride production subcategory. The provisions of this subpart are applicable to discharges...

21 CFR 582.6203 - Calcium hexametaphosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium hexametaphosphate. 582.6203 Section 582.6203 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6203 Calcium hexametaphosphate. (a) Product. Calcium hexametaphosphate. (b) Conditions of use. This...

Calcium leakage as a cause of the high resting tension in vascular smooth muscle from the spontaneously hypertensive rat.

PubMed

Noon, J P; Rice, P J; Baldessarini, R J

1978-03-01

Aortic strips from spontaneously hypertensive (SH) rats relax in calcium-free physiological medium and contract to approximately 60% of maximum when calcium is again restored to the medium. In vivid contrast, the resting tension of aortic strips from normal rats is unaffected by manipulation of the calcium concentration of the bathing medium. These findings, as well as the reduced sensitivity of aortic strips from SH rats to norepinephrine and the observation that aortic strips from SH rats relax at a faster rate in calcium-free medium in comparison with aortic strips from normal rats, are consistent with the hypothesis that vascular smooth muscle membranes from SH rats leak calcium at a rate that is only partially compensated by the calcium pump.

Yeast respond to hypotonic shock with a calcium pulse

NASA Technical Reports Server (NTRS)

Batiza, A. F.; Schulz, T.; Masson, P. H.

1996-01-01

We have used the transgenic AEQUORIN calcium reporter system to monitor the cytosolic calcium ([Ca2+]cyt) response of Saccharomyces cerevisiae to hypotonic shock. Such a shock generates an almost immediate and transient rise in [Ca2+]cyt which is eliminated by gadolinium, a blocker of stretch-activated channels. In addition, this transient rise in [Ca2+]cyt is initially insensitive to 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), an extracellular calcium chelator. However, BAPTA abruptly attenuates the maintenance of that transient rise. These data show that hypotonic shock generates a stretch-activated channel-dependent calcium pulse in yeast. They also suggest that the immediate calcium influx is primarily generated from intracellular stores, and that a sustained increase in [Ca2+]cyt depends upon extracellular calcium.

Calcium Intake and the Risk of Ovarian Cancer: A Meta-Analysis.

PubMed

Song, Xingxing; Li, Zongyao; Ji, Xinqiang; Zhang, Dongfeng

2017-06-30

Several epidemiological studies have evaluated the association between calcium intake and the risk of ovarian cancer. However, the results of these studies remain controversial. Thus, we performed a meta-analysis to explore the association between calcium intake and the risk of ovarian cancer. Pubmed, Embase and Web of Science were searched for eligible publications up to April 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Small-study effect was estimated using Egger's test and the funnel plot. Among 15 epidemiological studies involving 493,415 participants and 7453 cases eligible for this meta-analysis, 13 studies were about dietary calcium intake, 4 studies about dairy calcium intake and 7 studies about dietary plus supplemental calcium intake. When comparing the highest with the lowest intake, the pooled RRs of ovarian cancer were 0.80 (95% CI 0.72-0.89) for dietary calcium, 0.80 (95% CI 0.66-0.98) for dairy calcium and 0.90 (95% CI 0.65-1.24) for dietary plus supplemental calcium, respectively. Dietary calcium was significantly associated with a reduced risk of ovarian cancer among cohort studies (RR = 0.86, 95% CI 0.74-0.99) and among case-control studies ( RR = 0.75, 95% CI 0.64-0.89). In subgroup analysis by ovarian cancer subtypes, we found a statistically significant association between the dietary calcium ( RR = 0.78, 95% CI 0.69-0.88) and the risk of epithelial ovarian cancer (EOC). This meta-analysis indicated that increased calcium intake might be inversely associated with the risk of ovarian cancer; this still needs to be confirmed by larger prospective cohort studies.

Calcium Intake and the Risk of Ovarian Cancer: A Meta-Analysis

PubMed Central

Song, Xingxing; Li, Zongyao; Ji, Xinqiang; Zhang, Dongfeng

2017-01-01

Several epidemiological studies have evaluated the association between calcium intake and the risk of ovarian cancer. However, the results of these studies remain controversial. Thus, we performed a meta-analysis to explore the association between calcium intake and the risk of ovarian cancer. Pubmed, Embase and Web of Science were searched for eligible publications up to April 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Small-study effect was estimated using Egger’s test and the funnel plot. Among 15 epidemiological studies involving 493,415 participants and 7453 cases eligible for this meta-analysis, 13 studies were about dietary calcium intake, 4 studies about dairy calcium intake and 7 studies about dietary plus supplemental calcium intake. When comparing the highest with the lowest intake, the pooled RRs of ovarian cancer were 0.80 (95% CI 0.72–0.89) for dietary calcium, 0.80 (95% CI 0.66–0.98) for dairy calcium and 0.90 (95% CI 0.65–1.24) for dietary plus supplemental calcium, respectively. Dietary calcium was significantly associated with a reduced risk of ovarian cancer among cohort studies (RR = 0.86, 95% CI 0.74–0.99) and among case-control studies (RR = 0.75, 95% CI 0.64–0.89). In subgroup analysis by ovarian cancer subtypes, we found a statistically significant association between the dietary calcium (RR = 0.78, 95% CI 0.69–0.88) and the risk of epithelial ovarian cancer (EOC). This meta-analysis indicated that increased calcium intake might be inversely associated with the risk of ovarian cancer; this still needs to be confirmed by larger prospective cohort studies. PMID:28665326

Investigation of calcium-dependent activity and conformational dynamics of zebra fish 12-lipoxygenase.

PubMed

Mittal, Monica; Hasan, Mahmudul; Balagunaseelan, Navisraj; Fauland, Alexander; Wheelock, Craig; Rådmark, Olof; Haeggström, Jesper Z; Rinaldo-Matthis, Agnes

2017-08-01

A 12-lipoxygenase in zebra fish (zf12-LOX) was found to be required for normal embryonic development and LOXs are of great interest for targeted drug designing. In this study, we investigate the structural-functional aspects of zf12-LOX in response to calcium. A soluble version of zf12-LOX was created by mutagenesis. Based on multiple sequence alignment, we mutated the putative calcium-responsive amino acids in N-PLAT domain of soluble zf12-LOX. Using a series of biophysical methods, we ascertained the oligomeric state, stability, structural integrity and conformational changes of zf12-LOX in response to calcium. We also compared the biophysical properties of soluble zf12-LOX with the mutant in the absence and presence of calcium. Here we provide a detailed characterization of soluble zf12-LOX and the mutant. Both proteins exist as compact monomers in solution, however the enzyme activity of soluble zf12-LOX is significantly increased in presence of calcium. We find that the stimulatory effect of calcium on zf12-LOX is related to a change in protein structure as observed by SAXS, adopting an open-state. In contrast, enzyme with a mutated calcium regulatory site has reduced activity-response to calcium and restricted large re-modeling, suggesting that it retains a closed-state in response to calcium. Taken together, our study suggests that Ca 2+ -dependent regulation is associated with different domain conformation(s) that might change the accessibility to substrate-binding site in response to calcium. The study can be broadly implicated in better understanding the mode(s) of action of LOXs, and the enzymes regulated by calcium in general. Copyright © 2017 Elsevier B.V. All rights reserved.

Redox and Activation of Protein Kinase A Dysregulates Calcium Homeostasis in Pulmonary Vein Cardiomyocytes of Chronic Kidney Disease.

PubMed

Huang, Shih-Yu; Chen, Yao-Chang; Kao, Yu-Hsun; Hsieh, Ming-Hsiung; Lin, Yung-Kuo; Chen, Shih-Ann; Chen, Yi-Jen

2017-07-12

Chronic kidney disease (CKD) increases the occurrence of atrial fibrillation and pulmonary vein (PV) arrhythmogenesis. Calcium dysregulation and reactive oxygen species (ROS) enhance PV arrhythmogenic activity. The purposes of this study were to investigate whether CKD modulates PV electrical activity through dysregulation of calcium homeostasis and ROS. Biochemical and electrocardiographic studies were conducted in rabbits with and without CKD (induced by 150 mg/kg per day neomycin sulfate and 500 mg/kg per day cefazolin). Confocal microscopy with fluorescence and a whole-cell patch clamp were applied to study calcium homeostasis and electrical activities in control and CKD isolated single PV cardiomyocytes with or without treatment with H89 (1 μmol/L, a protein kinase A inhibitor) and MPG (N-[2-mercaptopropionyl]glycine; 100 μmol/L, a ROS scavenger). The ROS in mitochondria and cytosol were evaluated via intracellular dye fluorescence and lipid peroxidation. CKD rabbits had excessive atrial premature captures over those of control rabbits. Compared with the control, CKD PV cardiomyocytes had a faster beating rate and larger calcium transient amplitudes, sarcoplasmic reticulum calcium contents, sodium/calcium exchanger currents, and late sodium currents but smaller L-type calcium current densities. CKD PV cardiomyocytes had a higher frequency and longer duration of calcium sparks and more ROS in the mitochondria and cytosol than did controls. Moreover, H89 suppressed all calcium sparks in CKD PV cardiomyocytes, and H89- and MPG-treated CKD PV cardiomyocytes had similar calcium transients compared with control PV cardiomyocytes. CKD increases PV arrhythmogenesis with enhanced calcium-handling abnormalities through activation of protein kinase A and ROS. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Imaging-based assessment of the mineral composition of urinary stones: an in vitro study of the combination of hounsfield unit measurement in noncontrast helical computerized tomography and the twinkling artifact in color Doppler ultrasound.

PubMed

Hassani, Hakim; Raynal, Gauthier; Spie, Romain; Daudon, Michel; Vallée, Jean-Noël

2012-05-01

We evaluated the value of combining noncontrast helical computerized tomography (NCHCT) and color Doppler ultrasound in the assessment of the composition of urinary stones. In vitro, we studied 120 stones of known composition, that separate into the five main types: 18 calcium oxalate monohydrate (COM) stones, 41 calcium oxalate dihydrate (COD) stones, 24 uric acid stones, 25 calcium phosphate stones and 12 cystine calculi. Stones were characterized in terms of their Hounsfield density (HU) in NCHCT and the presence of a twinkling artifact (TA) in color Doppler ultrasound. There were statistically significant HU differences between calcium and non-calcium stones (p < 0.001), calcium oxalate stones and calcium phosphate stones (p < 0.001) and uric acid stones and cystine calculi (p < 0.001) but not between COM and COD stones (p = 0.786). Hence, the HU was a predictive factor of the composition of all types of stones, other than for COM and COD stones within the calcium oxalate class (p > 0.05). We found that the TA does not enable differentiation between calcium and non-calcium stones (p > 0.999), calcium oxalate stones and calcium phosphate stones (p = 0.15), or uric acid stones and cystine calculi (p = 0.079). However, it did reveal a significant difference between COM and COD stones (p = 0.002). The absence of a TA is a predictive factor for the presence of COM stones (p = 0.008). Hence, the association of NCHCT and Doppler enables the accurate classification of the five types of stones in vitro. Copyright © 2012 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Calcium plus vitamin D3 supplementation facilitated fat loss in overweight and obese college students with very-low calcium consumption: a randomized controlled trial.

PubMed

Zhu, Wei; Cai, Donglian; Wang, Ying; Lin, Ning; Hu, Qingqing; Qi, Yang; Ma, Shuangshuang; Amarasekara, Sidath

2013-01-08

Recent evidence suggests that higher calcium and/or vitamin D intake may be associated with lower body weight and better metabolic health. Due to contradictory findings from intervention trials, we investigated the effect of calcium plus vitamin D3 (calcium+D) supplementation on anthropometric and metabolic profiles during energy restriction in healthy, overweight and obese adults with very-low calcium consumption. Fifty-three subjects were randomly assigned in an open-label, randomized controlled trial to receive either an energy-restricted diet (-500 kcal/d) supplemented with 600 mg elemental calcium and 125 IU vitamin D3 or energy restriction alone for 12 weeks. Repeated measurements of variance were performed to evaluate the differences between groups for changes in body weight, BMI, body composition, waist circumference, and blood pressures, as well as in plasma TG, TC, HDL, LDL, glucose and insulin concentrations. Eighty-one percent of participants completed the trial (85% from the calcium + D group; 78% from the control group). A significantly greater decrease in fat mass loss was observed in the calcium + D group (-2.8±1.3 vs.-1.8±1.3 kg; P=0.02) than in the control group, although there was no significant difference in body weight change (P>0.05) between groups. The calcium + D group also exhibited greater decrease in visceral fat mass and visceral fat area (P<0.05 for both). No significant difference was detected for changes in metabolic variables (P>0.05). Calcium plus vitamin D3 supplementation for 12 weeks augmented body fat and visceral fat loss in very-low calcium consumers during energy restriction. ClinicalTrials.gov (NCT01447433, http://clinicaltrials.gov/).

Prevention of nutritional rickets in Nigerian children with dietary calcium supplementation.

PubMed

Thacher, Tom D; Fischer, Philip R; Isichei, Christian O; Zoakah, Ayuba I; Pettifor, John M

2012-05-01

Nutritional rickets in Nigerian children usually results from dietary calcium insufficiency. Typical dietary calcium intakes in African children are about 200mg daily (approximately 20-28% of US RDAs for age). We sought to determine if rickets could be prevented with supplemental calcium or with an indigenous food rich in calcium. We enrolled Nigerian children aged 12 to 18months from three urban communities. Two communities were assigned calcium, either as calcium carbonate (400mg) or ground fish (529±109mg) daily, while children in all three communities received vitamin A (2500IU) daily as placebo. Serum markers of mineral homeostasis and forearm bone density (pDEXA) were measured and radiographs were obtained at enrollment and after 18months of supplementation. The overall prevalence of radiographic rickets at baseline was 1.2% and of vitamin D deficiency [serum 25(OH)D<12ng/ml] 5.4%. Of 647 children enrolled, 390 completed the 18-month follow-up. Rickets developed in 1, 1, and 2 children assigned to the calcium tablet, ground fish, and control groups, respectively (approximate incidence 6.4/1000 children/year between 1 and 3years of age). Children who developed rickets in the calcium-supplemented groups had less than 50% adherence. Compared with the group that received no calcium supplementation, the groups that received calcium had a greater increase in areal bone density of the distal and proximal 1/3 radius and ulna over time (P<0.04). We conclude that calcium supplementation increased areal bone density at the radius and ulna, but a larger sample size would be required to determine its effect on the incidence of rickets. Copyright © 2012 Elsevier Inc. All rights reserved.

Calcium binding properties of calcium dependent protein kinase 1 (CaCDPK1) from Cicer arietinum.

PubMed

Dixit, Ajay Kumar; Jayabaskaran, Chelliah

2015-05-01

Calcium plays a crucial role as a secondary messenger in all aspects of plant growth, development and survival. Calcium dependent protein kinases (CDPKs) are the major calcium decoders, which couple the changes in calcium level to an appropriate physiological response. The mechanism by which calcium regulates CDPK protein is not well understood. In this study, we investigated the interactions of Ca(2+) ions with the CDPK1 isoform of Cicer arietinum (CaCDPK1) using a combination of biophysical tools. CaCDPK1 has four different EF hands as predicted by protein sequence analysis. The fluorescence emission spectrum of CaCDPK1 showed quenching with a 5 nm red shift upon addition of calcium, indicating conformational changes in the tertiary structure. The plot of changes in intensity against calcium concentrations showed a biphasic curve with binding constants of 1.29 μM and 120 μM indicating two kinds of binding sites. Isothermal calorimetric (ITC) titration with CaCl2 also showed a biphasic curve with two binding constants of 0.027 μM and 1.7 μM. Circular dichroism (CD) spectra showed two prominent peaks at 208 and 222 nm indicating that CaCDPK1 is a α-helical rich protein. Calcium binding further increased the α-helical content of CaCDPK1 from 75 to 81%. Addition of calcium to CaCDPK1 also increased fluorescence of 8-anilinonaphthalene-1-sulfonic acid (ANS) indicating exposure of hydrophobic surfaces. Thus, on the whole this study provides evidence for calcium induced conformational changes, exposure of hydrophobic surfaces and heterogeneity of EF hands in CaCDPK1. Copyright © 2015 Elsevier GmbH. All rights reserved.

The degree of resistance of erythrocyte membrane cytoskeletal proteins to supra-physiologic concentrations of calcium: an in vitro study.

PubMed

Mostafavi, Ebrahim; Nargesi, Arash Aghajani; Ghazizadeh, Zaniar; Larry, Mehrdad; Farahani, Roya Horabad; Morteza, Afsaneh; Esteghamati, Alireza; Vigneron, Claude; Nakhjavani, Manouchehr

2014-08-01

Calcium is a key regulator of cell dynamics. Dysregulation of its cytosolic concentration is implicated in the pathophysiology of several diseases. This study aimed to assess the effects of calcium on the network of membrane cytoskeletal proteins. Erythrocyte membranes were obtained from eight healthy donors and incubated with 250 µM and 1.25 mM calcium solutions. Membrane cytoskeletal proteins were quantified using SDS-PAGE at baseline and after 3 and 5 days of incubation. Supra-physiologic concentrations of calcium (1.25 mM) induced a significant proteolysis in membrane cytoskeletal proteins, compared with magnesium (p < 0.001). Actin exhibited the highest sensitivity to calcium-induced proteolysis (6.8 ± 0.3 vs. 5.3 ± 0.6, p < 0.001), while spectrin (39.9 ± 1.0 vs. 40.3 ± 2.0, p = 0.393) and band-6 (6.3 ± 0.3 vs. 6.8 ± 0.8, p = 0.191) were more resistant to proteolysis after incubation with calcium in the range of endoplasmic reticulum concentrations (250 µM). Aggregation of membrane cytoskeletal proteins was determined after centrifugation and was significantly higher after incubation with calcium ions compared with control, EDTA and magnesium solutions (p < 0.001). In a supra-physiologic range of 1.25-10 mM of calcium ions, there was a nearly perfect linear relationship between calcium concentration and aggregation of erythrocyte membrane cytoskeletal proteins (R(2) = 0.971, p < 0.001). Our observation suggests a strong interaction between calcium ions and membrane cytoskeletal network. Cumulative effects of disrupted calcium homeostasis on cytoskeletal proteins need to be further investigated at extended periods of time in disease states.

Cumulative effects of calcium supplementation and physical activity on bone accretion in premenarchal children: a double-blind randomised placebo-controlled trial.

PubMed

Courteix, D; Jaffré, C; Lespessailles, E; Benhamou, L

2005-06-01

High calcium intake combined with physical activity during childhood have been shown to improve bone mass accrual and bone mineral density. Our aim was to study the combined effect of calcium and exercise on bone gain in children. Two milk-powder products containing either 800 mg of calcium phosphate (calcium) or not (placebo) were randomly allocated to 113 healthy premenarchal girls on a daily basis for 1 year. The group was composed of 63 exercise (7.2 +/- 4 hours of exercise/week) and 50 sedentary (1.2 +/- 0.8 hours of exercise/week) children. The final experiment had 4 groups: exercise/calcium (n = 12), exercise/placebo (n = 42), sedentary/calcium (n = 10), and sedentary/placebo (n = 21). Bone mineral density (BMD) at 6 skeletal sites and body composition were determined by DXA. Bone age was calculated and the daily spontaneous calcium intake was assessed by a frequency questionnaire. All the tests were performed at baseline and 1 year by the same observer. BMD gains were significantly greater in the exercise/calcium group than in other groups at the total body (increase of 6.3 %, p < 0.05), lumbar spine (11 %, p < 0.05), femoral neck (8.2 %, p < 0.02), and Ward's triangle (9.3 %, p < 0.01). There was no difference between the other groups. These data suggest that calcium supplementation increases the effect of physical exercise on bone mineral acquisition in the period preceding puberty, and that calcium supplementation without physical activity does not improve the BMD acquisition during this period. Physical exercise that stimulates bone accretion needs a high calcium intake to be completely effective.