To see the other types of publications on this topic, follow the link: Calcium concentration.
Journal articles on the topic 'Calcium concentration'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Calcium concentration.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Zhu, Zhiming, Martin Tepel, Marcus Neusser, and Walter Zidek. "Low Concentrations of Ouabain Increase Cytosolic Free Calcium Concentration in Rat Vascular Smooth Muscle Cells." Clinical Science 90, no. 1 (1996): 9–12. http://dx.doi.org/10.1042/cs0900009.
Full textAbstract:
1. Low ouabain concentrations in the nanomolar range significantly increased cytosolic free calcium concentration. 2. The ouabain-induced cytosolic free calcium concentration increase was due to transplasmamembrane calcium influx, which could be prevented in the absence of extracellular calcium or by addition of the calcium channel blocker nifedipine. 3. The amount of stored cellular Ca2+, as determined by the thapsigargin-induced cytosolic free calcium concentration increase, was also enhanced by 1 nmol/l ouabain. 4. It is concluded that low ouabain concentrations affect intracellular cytosolic free calcium concentration homoeostasis.
2
Cho, Hyunji, Jisoo Lee, Seoyoung Jang, et al. "CaSR-Mediated hBMSCs Activity Modulation: Additional Coupling Mechanism in Bone Remodeling Compartment." International Journal of Molecular Sciences 22, no. 1 (2020): 325. http://dx.doi.org/10.3390/ijms22010325.
Full textAbstract:
Near the bone remodeling compartments (BRC), extracellular calcium concentration (Ca2+o) is locally elevated and bone marrow stromal cells (BMSCs) close to the BRC can be exposed to high calcium concentration. The calcium-sensing receptor (CaSR) is known to play a key role in maintaining extracellular calcium homeostasis by sensing fluctuations in the levels of extracellular calcium (Ca2+o). When human BMSCs (hBMSCs) were exposed to various calcium concentrations (1.8, 3, 5, 10, 30 mM), moderate-high extracellular calcium concentrations (3–5 mM) stimulated proliferation, while a high calcium concentration (30 mM) inhibited the proliferation. Exposure to various calcium concentrations did not induce significant differences in the apoptotic cell fraction. Evaluation of multi-lineage differentiation potential showed no significant difference among various calcium concentration groups, except for the high calcium concentration (30 mM) treated group, which resulted in increased calcification after in vitro osteogenic differentiation. Treatment of NPS2143, a CaSR inhibitor, abolished the stimulatory effect on hBMSCs proliferation and migration indicating that CaSR is involved. These results suggest that the calcium concentration gradient near the BRC may play an important role in bone remodeling by acting as an osteoblast–osteoclast coupling mechanism through CaSR.
3
Weinreich, Thomas, A. Colombi, H. H. Echterhoff, et al. "Transperitoneal Calcium Mass Transfer using Dialv Sate with a Low Calcium Concentration (1.0 mM)." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 13, no. 2_suppl (1993): 467–70. http://dx.doi.org/10.1177/089686089301302s117.
Full textAbstract:
Lower dialysate calcium concentrations were recently proposed to overcome the risk of hypercalcemia In continuous ambulatory peritoneal dialysis (CAPD) patients on calcium containing phosphate binders and/or vitamin D metabolites using the standard dialysate calcium concentration (sCa) of 1.75 mM. To assess transperitoneal calcium mass transfer (CaMT) in CAPD patients using a dialysate with a low calcium concentration (LCa, 1.00 mM), 18 stable patients were randomly allocated to receive either LCa or SCa. CaMT was assessed over 4 hours using 2L dialysate bags with three different dialysate glucose concentrations (1.5%, 2.3%, 4.25%). Total serum calcium (tCa), Ionized calcium (iCa), and the exact dialysate volume were measured before and after the 4-hour dwell. A sample of the drained dialysate was obtained to measure the dialysate calcium concentration. The tCa and iCa levels were not significantly different In both groups prior to and did not change throughout the test. CaMT (median/range) was .0.64 mmol/exchange (0.35 –1.29 mmol/exchange) using LCa with 1.5% glucose compared to 0.23 mmol (.0.18 -0.87 mmol) with SCa (p<0.0001). CaMT was negatively correlated to ICa and ultrafiltration volume [4.25%: LCa -1.22 (.0.84 -1.9); SCa .0.43 (-1.35 -0.13); p<0.001]. In summary, LCa results in a loss of calcium into the dialysate even at low ultrafiltration volumes and serum ICa levels. This might facilitate the prevention and therapy of renal osteodystrophy with calclum-containing phosphate binders and calcitriol. However, patients using LCa must be carefully monitored for calcium homeostasis and bone turnover.
4
Patel, Prerna, M. Zulf Mughal, Pinal Patel, et al. "Dietary calcium intake influences the relationship between serum 25-hydroxyvitamin D3 (25OHD) concentration and parathyroid hormone (PTH) concentration." Archives of Disease in Childhood 101, no. 4 (2015): 316–19. http://dx.doi.org/10.1136/archdischild-2015-308985.
Full textAbstract:
ObjectivesTo investigate whether dietary calcium intake will modify the relationship between serum 25-hydroxyvitamin D3 (25OHD) with intact serum parathyroid hormone (PTH) concentrations in apparently healthy Indian adolescents.Study designCross-sectional study.Setting and participantsApparently healthy adolescents aged 10–14 years (n=181), from Gujarat, western India. Study conducted from January 2012 to March 2014.MethodsSerum 25OHD concentrations and intact serum PTH concentrations (both using chemiluminescent microparticle immunoassay) were measured. Diet was recorded through 24 h diet recall and calcium intake was computed (C-diet V.2.1). To assess relationship between 25OHD and PTH, data were dichotomised according to median calcium intakes (520 mg/day) and relationship between serum 25OHD and PTH in the two subgroups was plotted.ResultsSubjects with calcium intakes above median (>520 mg/day) had lower intact serum PTH values for given serum 25OHD concentration while those with calcium intakes below median (<520 mg/day) had higher intact serum PTH values for given serum 25OHD concentration. Serum 25OHD concentration was negatively correlated with intact serum PTH concentration at lower as well as higher calcium intakes (r=− 0.606 and −0.483, respectively, p<0.01 for both). Using a regression analysis, predicted values for intact serum PTH concentration for the given serum 25OHD concentrations were plotted. The plot revealed a negative shift with increasing calcium intake.ConclusionsDietary calcium intake modifies the relationship between serum 25OHD concentrations and intact serum PTH concentrations. Thus, dietary calcium intake should be taken into account when assessing an individual's vitamin D status.
5
Weber, Lynn P., Wing L. Chow, Janice Moshenko, Slavica Belsher, and Kathleen M. MacLeod. "Pharmacological investigation of signaling mechanisms contributing to phasic and tonic components of the contractile response of rat arteries to noradrenaline." Canadian Journal of Physiology and Pharmacology 73, no. 5 (1995): 594–601. http://dx.doi.org/10.1139/y95-075.
Full textAbstract:
The mechanisms contributing to the contractile responses to two different concentrations of noradrenaline (NA) in rat aorta and mesenteric artery were compared using nifedipine, which inhibits calcium influx through dihydropyridine-sensitive channels, ryanodine, which depletes intracellular calcium stores, and calphostin C, which inhibits protein kinase C (PKC). Both submaximal and maximal concentrations of NA induced a biphasic response in aorta and mesenteric artery, with an early fast phase and a later sustained tonic component. Calcium release from intracellular stores contributed to the phasic component of contraction to both concentrations of NA in aorta, although to a greater extent to the submaximal concentration. In aorta, inhibiting both intracellular calcium release and calcium influx through dihydropyridine-sensitive channels simultaneously or inhibiting PKC activity alone significantly reduced the tonic response to a maximal concentration of NA. However, the tonic response to a submaximal concentration of NA in aorta was significantly inhibited only when intracellular calcium stores were depleted with ryanodine. In mesenteric artery, the phasic response to a maximal concentration of NA was significantly depressed only when both calcium influx and intracellular calcium release were inhibited simultaneously. However, the phasic response to a submaximal concentration of NA was significantly inhibited by blocking calcium influx alone, but not by blocking intracellular calcium release alone. The tonic component of the contractile response to both concentrations of NA in mesenteric artery appeared to be mediated in part by calcium from both intracellular and extracellular sources. However, the submaximal concentration relied on calcium influx to a greater extent than the maximal concentration, while PKC contributed to a greater extent to the response to the maximal concentration of NA in this artery. These results indicate that the relative contributions of the signaling mechanisms activated by NA differ between maximal and submaximal concentrations of the agonist as well as between different arteries.Key words: noradrenaline, vasoconstriction, ryanodine, nifedipine, calphostin C.
6
Li, Hui, Yaoyao Zhao, Xiaohang Weng, et al. "The Most Suitable Calcium Concentration for Growth Varies among Different Tree Species—Taking Pinus tabuliformis, Pinus sylvestris var. mongolica, Populus, and Morus alba as Examples." Forests 14, no. 7 (2023): 1437. http://dx.doi.org/10.3390/f14071437.
Full textAbstract:
Ca2+ is a crucial second messenger in plant cells that plays a vital role in various physiological and biochemical processes, including plant growth and development, photosynthesis, and enzyme regulation. Exogenous calcium concentrations can have different effects on plant growth. The purpose of this study was to determine the appropriate calcium concentration for the growth of four tree seedlings, namely Pinus tabuliformis, Pinus sylvestris var. mongolica, Populus, and Morus alba seedlings, and whether this optimal calcium concentration varies among different tree species. This study utilized five calcium concentration gradients (0, 100, 200, 400, 800 mg·kg−1) for each species with three repeated treatments. To determine each species’ calcium concentration needs, several growth indices, photosynthetic metrics, chlorophyll fluorescence parameters, water usage efficiency, and antioxidant enzyme activities were analyzed. The results showed that exogenous calcium significantly affected the growth and development of each seedling. The growth, biomass, photosynthetic parameters, photosynthetic products, photosynthetic pigments, water use efficiency, and antioxidant enzyme activity all increased initially and then decreased with the increasing calcium concentration. The exogenous calcium supply increased the concentration of calcium in the leaves. Thus, there was an optimal calcium concentration for plant growth, and a high or low calcium concentration was not conducive to plant growth. Furthermore, this study found that the optimum calcium concentration of different tree species was different. The optimal calcium concentration for Pinus tabuliformis, Pinus sylvestris var. mongolica, Populus, and Morus alba seedlings was 100, 100, 200, and 400 mg·kg−1, respectively, with broadleaf seedlings requiring higher calcium concentrations than coniferous seedlings.
7
Chew, Dennis J., Mark Leonard, and William Muir. "Effect of sodium bicarbonate infusions on ionized calcium and total calcium concentrations in serum of clinically normal cats." American Journal of Veterinary Research 50, no. 1 (1989): 145–50. https://doi.org/10.2460/ajvr.1989.50.01.145.
Full textAbstract:
SUMMARY The effects of sodium bicarbonate (0.5 mEq/kg of body weight, 1.0 mEq/kg, 2.0 mEq/kg, and 4.0 mEq//kg) on ionized and total calcium concentrations were determined in clinically normal cats. Also, serum pH, whole blood pH, and serum albumin, serum total protein, and serum phosrus concentrations were measured. Intravenous administration of sodium bicarbonate to awake cats decreased serum ionized calcium and serum total calcium concentrations. All dosages of sodium bicarbonate were associated with significant decreases of serum ionized calcium concentration. This effect lasted for > 180 minutes when cats were given 2.0 mEq/kg or 4.0 mEq/kg. When cats were given 4 mEq of sodium bicarbonate/kg, serum ionized calcium concentration was significantly decreased, compared with that when cats were given lower doses, but only at 10 minutes after infusion. After sodium bicarbonate infusion, serum total calcium concentration, measured by ion-specific electrode and colorimetry, was lower than baseline values at most of the times evaluated. Decreases in serum ionized calcium and serum total calcium concentrations can be attributed only in part to an increase in serum or whole blood pH and to a decrease in serum protein concentration. Serum total calcium concentrations measured by ionspecific electrode and by colorimetry were positively correlated, but the variability was high. Only 44 % of the variability in serum ionized calcium concentration could be predicted when serum total calcium, albumin, total protein, phosphorus, and bicarbonate concentrations and pH were considered.
8
Zhu, Wen Kun, Xue Gang Luo, Xiao Yan Lin, and Pan He. "Effects of Ca2+ Concentration on Calcium Carbonate Crystallization in Lignin Solution System." Materials Science Forum 695 (July 2011): 521–24. http://dx.doi.org/10.4028/www.scientific.net/msf.695.521.
Full textAbstract:
The calcium carbonate crystallization was controlled by Ca2+concentrations, under the system of lignin solution with concentration of 10 g / L. Its morphology, structure and thermal decomposition were characterized by FT-IR, SEM, XRD and TG. Results showed that in lignin solution system, concentration of Ca2+had significant effects on the crystallized morphology, orientation and crystallinity of calcium carbonate. Calcium carbonate crystal under low Ca2+concentration had more uniform size while under high Ca2+concentration which tended to form various sizes with more complete crystallization. The calcium carbonate crystals were all calcite calcium carbonate, which formed under different Ca2+concentrations.
9
Flanders, J. A., S. Neth, H. N. Erb, and F. A. Kallfelz. "Functional analysis of ectopic parathyroid activity in cats." American Journal of Veterinary Research 52, no. 8 (1991): 1336–40. http://dx.doi.org/10.2460/ajvr.1991.52.08.1336.
Full textAbstract:
Summary The ability of ectopic parathyroid tissue to support calcium homeostasis was evaluated by measuring serum concentrations of calcium, phosphorus, albumin, magnesium, and parathyroid hormone before and for 12 weeks after bilateral thyroparathyroidectomy in 14 cats. During the immediate postoperative period, significant decrease was observed in serum calcium, magnesium, and parathyroid hormone (pth) concentrations. Serum pth concentration remained subnormal and did not significantly increase during the 12-week observation period. Despite persistent hypoparathyroidism, serum calcium and magnesium concentrations gradually increased. Ectopic parathyroid tissue is not capable of maintaining normal serum calcium concentration immediately after thyroparathyroidectomy. Serum calcium concentration gradually normalizes after thyroparathyroidectomy, apparently by means of a pth-independent mechanism.
10
Fluck, R. J., A. C. McMahon, F. M. Alameddine, A. B. S. Dawnay, L. R. I. Baker, and A. E. G. Raine. "Platelet cytosolic free calcium concentration and parathyroid hormone: changing relationships with haemodialysis in end-stage renal disease." Clinical Science 82, no. 6 (1992): 651–58. http://dx.doi.org/10.1042/cs0820651.
Full textAbstract:
1. Twelve patients receiving haemodialysis for end-stage renal failure were studied at a single dialysis session. Platelet cytosolic calcium concentration, plasma ionized calcium concentration and serum parathyroid hormone concentration were measured before dialysis, mid-dialysis and 30 min after dialysis. 2. Plasma ionized calcium concentration increased towards dialysate calcium concentrations, falling insignificantly after cessation of dialysis. Serum parathyroid hormone concentration fell by 39% during dialysis, with incomplete recovery afterwards. There was no overall change in platelet cytosolic calcium concentration. 3. Patients were divided into two subgroups: low parathyroid hormone (serum parathyroid hormone concentration < 10 pmol/l) and high parathyroid hormone (serum parathyroid hormone concentration > 10 pmol/l). Before dialysis, values of platelet cytosolic calcium concentration or plasma ionized calcium concentration were not statistically different between the subgroups, but the platelet cytosolic calcium concentration was higher in the high-parathyroid hormone subgroup during and after dialysis. 4. Before haemodialysis there was a linear correlation between plasma ionized calcium concentration and platelet cytosolic calcium concentration, which disappeared during dialysis. In contrast, there was no relationship between serum parathyroid hormone concentration and platelet cytosolic calcium concentration before dialysis, but after dialysis a hyperbolic relationship was evident. 5. These results suggest that uraemic toxins may interfere with cytosolic calcium homoeostasis, allowing passive diffusion of extracellular calcium to influence the resting concentration, and that this effect is reversible by haemodialysis.
11
Christensen, Kenneth A., Jesse T. Myers, and Joel A. Swanson. "pH-dependent regulation of lysosomal calcium in macrophages." Journal of Cell Science 115, no. 3 (2002): 599–607. http://dx.doi.org/10.1242/jcs.115.3.599.
Full textAbstract:
Calcium measurements in acidic vacuolar compartments of living cells are few, primarily because calibration of fluorescent probes for calcium requires knowledge of pH and the pH-dependence of the probe calcium-binding affinities. Here we report pH-corrected measurements of free calcium concentrations in lysosomes of mouse macrophages, using both ratiometric and time-resolved fluorescence microscopy of probes for pH and calcium. Average free calcium concentration in macrophage lysosomes was 4-6×10-4 M, less than half of the extracellular calcium concentration, but much higher than cytosolic calcium levels. Incubating cells in varying extracellular calcium concentrations did not alter lysosomal pH, and had only a modest effect on lysosomal calcium concentrations, indicating that endocytosis of extracellular fluid provided a small but measurable contribution to lysosomal calcium concentrations. By contrast, increases in lysosomal pH, mediated by either bafilomycin A1 or ammonium chloride, decreased lysosomal calcium concentrations by several orders of magnitude. Re-acidification of the lysosomes allowed rapid recovery of lysosomal calcium concentrations to higher concentrations. pH-dependent reductions of lysosomal calcium concentrations appeared to result from calcium movement out of lysosomes into cytoplasm,since increases in cytosolic calcium levels could be detected upon lysosome alkalinization. These studies indicate that lysosomal calcium concentration is high and is maintained in part by the proton gradient across lysosomal membranes. Moreover, lysosomes could provide an intracellular source for physiological increases in cytosolic calcium levels.
12
Yuan, Weiling, Shangyong Yuan, Zhixiong Liu, Leifu Chen, and Zhengming Qiu. "Effect of Foliar Application of CaCl2 on Lettuce Growth and Calcium Concentrations with Organic and Conventional Fertilization." HortScience 53, no. 6 (2018): 891–94. http://dx.doi.org/10.21273/hortsci13056-18.
Full textAbstract:
Calcium-rich vegetables in diet could minimize calcium deficiency and maximize good health and well-being. The aim of the present study was to determine the effect of different levels of foliar application of CaCl2 on lettuce (Lactuca sativa L.) growth and calcium concentrations with the application of organic and conventional fertilizers. Pot experiments were conducted with three calcium levels (60, 120, and 180 mg·L−1 of CaCl2) of an organic fertilizer (3N–0.8P–3.5K) and commercial conventional fertilizer (15N–15P–15K). Calcium in whole oven-ashed samples of shoots was analyzed by atomic absorption spectrometry. Nine lettuce cultivars including butterhead, romaine, and loose-leaf phenotype were tested. These results revealed that the calcium concentration in lettuce significantly increased as calcium levels increased from 60 to 180 mg·L−1. Elevated calcium concentrations in organic and conventional fertilizers increased the concentration of calcium in lettuce from 1.82% at 60 mg·L−1 to a mean of 2.15% at 120 and 180 mg·L−1. The concentration of calcium in the loose-leaf phenotype was 2.17%, 2.47%, and 3.80% higher than that in the butterhead and romaine phenotypes at 60, 120, and 180 mg Ca/L, respectively. Furthermore, the significant difference in calcium concentration among cultivars ranged from 1.27% to 3.05%. ‘Perilla Green’, ‘Breen lettuce’, and ‘Salinas’ had the highest calcium concentrations followed by ‘Jericho lettuce’, ‘Salad Bowl’ and ‘Crisp’, and ‘Kaiser’, whereas ‘Valmaine’ and ‘Rosa Green’ had the lowest calcium concentrations. The present study revealed that selecting fertilizers and cultivars with high calcium concentration can increase the total calcium content of lettuce.
13
Kramer, R. E. "Angiotensin II causes sustained elevations in cytosolic calcium in glomerulosa cells." American Journal of Physiology-Endocrinology and Metabolism 255, no. 3 (1988): E338—E346. http://dx.doi.org/10.1152/ajpendo.1988.255.3.e338.
Full textAbstract:
Studies were conducted to examine the effects of angiotensin II on cytosolic free calcium concentration in bovine adrenal glomerulosa cells maintained in primary culture. The calcium indicator, fura-2, and discontinuous dual-wavelength fluorescence spectroscopy were used to measure cytosolic free calcium in superfused adherent cell monolayers. Basal cytosolic free calcium concentration was 63.7 +/- 3.3 nM. The threshold concentration for angiotensin II-stimulated increases in cytosolic calcium was 10(-14)-10(-13) M, and maximal elevation of cytosolic calcium was produced by 10(-9) M angiotensin II. Angiotensin II (10(-13) M) produced a gradual increase in cytosolic calcium concentration that plateaued after 3-5 min of superfusion at a level approximately 1.2 times that of control cells. The calcium signal invoked by a maximal concentration (10(-9) M) of angiotensin II, in contrast, was characterized by an immediate, intense (approximately 8-fold) increase in cytosolic calcium concentration that decayed within 5 min to a lower, but sustained, level 2.5-3 times that of control cells. The calcium signals invoked by intermediate concentrations (10(-12)-10(-10) M) of angiotensin II exhibited dose-dependent increases in magnitude and a gradual transition in nature between those invoked by threshold and maximal concentrations of the peptide. The effect of angiotensin II to increase cytosolic calcium concentration was accompanied by an increase in aldosterone output. The increase in steroidogenesis was most closely correlated with the magnitude of the initial calcium signal. At high concentrations (10(-10) and 10(-9) M) of angiotensin II, there was a clear dissociation between aldosterone output and the magnitude of the sustained calcium signal.(ABSTRACT TRUNCATED AT 250 WORDS)
14
Butler, D. G. "STANNIECTOMY INCREASES RENAL MAGNESIUM AND CALCIUM EXCRETION IN FRESHWATER NORTH AMERICAN EELS (ANGUILLA ROSTRATA)." Journal of Experimental Biology 181, no. 1 (1993): 107–18. http://dx.doi.org/10.1242/jeb.181.1.107.
Full textAbstract:
The corpuscles of Stannius are linked to the renal transport of magnesium in freshwater North American eels. The urinary magnesium concentration and rate of magnesium excretion increased 3 days after the corpuscles had been removed, a trend which continued throughout a 14 day observation period. There was no overall change in urine flow rates except for a brief 50 % reduction 2 days after stanniectomy. Plasma magnesium concentrations drifted downward after stanniectomy. In contrast, plasma calcium concentrations increased significantly within 2 days following stanniectomy and they continued to increase thereafter. Urinary calcium concentrations and the rate of urinary calcium excretion increased 7 days after stanniectomy, implying that the renal response was subject to the increase in plasma calcium concentration: the urine/plasma calcium ratio remained constant. Even though the urinary calcium concentration increased after stanniectomy, the increase in urinary magnesium concentration was proportionally greater.
15
Jeziorski, Adam, and Norman D. Yan. "Species identity and aqueous calcium concentrations as determinants of calcium concentrations of freshwater crustacean zooplankton." Canadian Journal of Fisheries and Aquatic Sciences 63, no. 5 (2006): 1007–13. http://dx.doi.org/10.1139/f06-019.
Full textAbstract:
Calcium (Ca) is a major component of the crustacean zooplankton carapace. As crustacean zooplankton obtain most of their Ca from lake water, taxa with high Ca demands may be negatively affected if environmental Ca concentrations fall below thresholds necessary for adequate Ca uptake rates. Currently, Ca concentrations are falling in many soft-water lakes with a history of acid deposition, both within Canada and globally. Hence, there is a need to identify species with high Ca demands. We analyzed Ca concentrations of eight crustacean zooplankton taxa from nine lakes spanning a 0.435 mg·L1 Ca gradient. Our objectives were to determine (i) if both species identity and lake Ca concentrations are determinants of zooplankton Ca concentration and (ii) if zooplankton Ca concentration varies seasonally. Large differences in Ca concentrations were observed among taxa. Levels in Daphnia sp. ranged from 2% to 8% of dry body weight, whereas levels in copepods and non-daphniid cladocera were much lower at 0.2%0.4%. Seasonal variation in zooplankton Ca concentration was negligible, but positive correlations with lake Ca concentration were detected, with up to twofold differences in Ca concentration between lakes in three of the eight species. Species identity was the most important determinant of crustacean zooplankton Ca concentration.
16
Stern, Peter. "Controlling cellular calcium concentration." Science 358, no. 6364 (2017): 759.1–759. http://dx.doi.org/10.1126/science.358.6364.759-a.
Full text
17
Breitwieser, Gerda E., and Lucio Gama. "Calcium-sensing receptor activation induces intracellular calcium oscillations." American Journal of Physiology-Cell Physiology 280, no. 6 (2001): C1412—C1421. http://dx.doi.org/10.1152/ajpcell.2001.280.6.c1412.
Full textAbstract:
Parathyroid hormone secretion is exquisitely sensitive to small changes in serum Ca2+concentration, and these responses are transduced via the Ca2+-sensing receptor (CaR). We utilized heterologous expression in HEK-293 cells to determine the effects of small, physiologically relevant perturbations in extracellular Ca2+ on CaR signaling via phosphatidylinositol-phospholipase C, using changes in fura 2 fluorescence to quantify intracellular Ca2+. Chronic exposure of CaR-transfected cells to Ca2+ in the range from 0.5 to 3 mM modulated the resting intracellular Ca2+concentration and the subsequent cellular responses to acute extracellular Ca2+ perturbations but had no effect on thapsigargin-sensitive Ca2+ stores. Modest, physiologically relevant increases in extracellular Ca2+concentration (0.5 mM increments) caused sustained (30–40 min) low-frequency oscillations of intracellular Ca2+ (∼45 s peak to peak interval). Oscillations were eliminated by 1 μM thapsigargin but were insensitive to protein kinase inhibitors (staurosporine, KN-93, or bisindolylmaleimide I). Staurosporine did increase the fraction of cells oscillating at a given extracellular Ca2+ concentration. Serum Ca2+ concentrations thus chronically regulate cells expressing CaR, and small perturbations in extracellular Ca2+ alter both resting intracellular Ca2+ as well as Ca2+ dynamics.
18
Hanssen, R. G., F. P. Lafeber, G. Flik, and S. E. Wendelaar Bonga. "Ionic and total calcium levels in the blood of the European eel (Anguilla anguilla): effects of stanniectomy and hypocalcin replacement therapy." Journal of Experimental Biology 141, no. 1 (1989): 177–86. http://dx.doi.org/10.1242/jeb.141.1.177.
Full textAbstract:
Removal of the corpuscles of Stannius (STX) in the freshwater European eel causes a marked increase in the concentrations of blood ionic calcium and protein-bound calcium. The hypercalcaemia peaks 20 days after STX and lasts at least another 20 days. In stanniectomized eels hypocalcin decreased both blood ionic and total calcium concentrations. The reduction of plasma total calcium concentration by hypocalcin is attributed to a reduction in blood ionic calcium concentration. We conclude that hypocalcin regulates blood ionic calcium levels in fish.
19
Takasugi, Satoshi, Tohru Matsui, and Hideo Yano. "Iron supplementation by intraperitoneal injection eliminates the accumulation of hepatic copper induced by excess calcium in rats." British Journal of Nutrition 102, no. 2 (2009): 258–63. http://dx.doi.org/10.1017/s0007114508184707.
Full textAbstract:
Excess calcium is well known to induce iron deficiency. Furthermore, excess calcium increases hepatic copper concentration and decreases renal copper concentration. We investigated the effect of iron supplementation on the tissue distribution of copper in rats given a high-calcium diet. Male rats (5 weeks old) were divided into four groups; a control group, and three groups given a diet containing 5-fold higher calcium than its requirement and an intraperitoneal iron supplementation of 0, 1 or 2 mg/week as iron dextran. The animals were fed their respective experimental diets with or without iron supplementation for 4 weeks. Although the high-calcium diet had no effect on calcium concentrations in the liver, kidney, testis, spleen and plasma, it reduced haematocrit and iron concentrations in the liver, kidney and testis and the rats had a moderate iron deficiency. The iron supplementation restored to normal these signs of iron deficiency. The high-calcium diet increased hepatic copper concentration but decreased plasma copper concentration and ceruloplasmin activity, which was restored by the iron supplementation. The copper concentration in bile was neither affected by the high-calcium diet nor the iron supplementation. The high-calcium diet decreased the copper concentration in the kidney, which was not restored by the iron supplementation. These results suggest that secondary iron deficiency stimulates hepatic accumulation of copper in rats given excess calcium by suppressing copper efflux into the circulation. The reduced renal copper concentration by excess calcium is independent of the iron deficiency.
20
Payne, R. B., A. J. Little, and R. T. Evans. "Albumin-adjusted calcium concentration in serum increases during normal pregnancy." Clinical Chemistry 36, no. 1 (1990): 142–44. http://dx.doi.org/10.1093/clinchem/36.1.142.
Full textAbstract:
Abstract Concentrations of total calcium and albumin were measured in serum specimens from 41 women at intervals before, during, and after 42 pregnancies. The albumin concentration decreased but the calcium decreased more slowly, so that the albumin-adjusted calcium concentration increased from conception to term. These findings, taken in conjunction with published observations of hypercalciuria, increased concentrations of 1,25-dihydroxycholecalciferol and calcitonin in serum, and decreased concentrations of intact parathyrin in serum, strongly suggest that maternal ionized calcium increases throughout normal pregnancy.
21
Queen, W. Gregory, Gay Y. Miller, and Margaret A. Masterson. "Effects of oral administration of a calcium-containing gel on serum calcium concentration in postparturient dairy cows." Journal of the American Veterinary Medical Association 202, no. 4 (1993): 607–9. http://dx.doi.org/10.2460/javma.1993.202.04.607.
Full textAbstract:
Summary: Various nutrious nutritional-supplement gels are being marketed for use in veterinary medicine. This study was designed to determine whether serum calcium, phosphorous, or magnesium concentrations were different between cows given a gel containing calcium chloride as its active ingredient (treated) and cows given inert carrier gel (control). The study revealed a significant (P < 0.01) increase in serum total calcium concentration within 5 minutes of administration of a calcium gel given to cows within 1 hour of parturition. Serum total calcium concentration had returned to baseline value by 24 hours after calcium gel administration. Serum inorganic phosphorus concentration also increased significantly (P < 0.05) after treatment. Significant changes in serum magnesium concentrations were not detected.
22
Yap, M. Y., M. W. Lim, and L. K. W. Brendan. "Influence of calcium macronutrient on tip burn occurrence in hydroponically cultivated lettuces." IOP Conference Series: Materials Science and Engineering 1257, no. 1 (2022): 012003. http://dx.doi.org/10.1088/1757-899x/1257/1/012003.
Full textAbstract:
Abstract Tip burn in hydroponics lettuce is an undesirable phenomenon identified by necrotic breakdown of marginal tissue of leaves. A deep-water culture hydroponics system was designed to determine the effect of increasing nutritional calcium concentration and varying nutritional calcium sources in alleviating the tip burn development for the hydroponics growth of lettuce (Lactuca sativa). Lettuces was cultivated separately in an untreated fish wastewater (150mg/L) and four treated fish wastewaters with calcium addition by calcium hydroxide and calcium carbonate to concentrations of 250 and 350mg/L respectively. Increasing calcium concentration from 150 to 350mg/L demonstrated not only an increase in tip burn incidence by 33.33% (calcium carbonate) and 50% (calcium hydroxide), but a slower plant growth in comparison with lettuces cultivated at 150mg/L. Besides, lettuces treated by calcium carbonate has greater leaf calcium concentrations by 48.17% at constant calcium concentration, attributed to its high solubility to release more Ca2+ ions in fish wastewater for plant adsorption. Results suggest that the addition of calcium carbonate to fish wastewater for hydroponics cultivation is more suitable for reducing the tip burn occurrence and growth inhibition at concentrations up to 150mg/L.
23
Drobatz, Kenneth J., and Dez Hughes. "Concentration of ionized calcium in plasma from cats with urethral obstruction." Journal of the American Veterinary Medical Association 211, no. 11 (1997): 1392–95. http://dx.doi.org/10.2460/javma.1997.211.11.1392.
Full textAbstract:
Objective To measure ionized calcium concentration in plasma from cats with urethral obstruction and to correlate these values with results of clinical biochemical analyses and physical examinations. Design Prospective study. Animals 24 male cats. Procedure Blood samples were obtained from each cat on admission, and PCV, pH, and concentrations of ionized calcium, total calcium, glucose, total solids, sodium, potassium, BUN, creatinine, chloride, magnesium, albumin, and phosphorus were determined. Mentation, tissue perfusion, and ECG recordings were also assessed. Results 18 (75%) cats had low ionized calcium concentrations (reference range, 2.4 to 2.8 mEq/L). Hypocalcemia was considered mild (2.0 to 2.36 mEq/L) in 9 (37.5%) cats, moderate (1.6 to 1.98 mEq/L) in 6 (25%), and severe (< 1.6 mEq/L) in 3 (12.5%). Significant positive correlations were found between ionized calcium concentration and heart rate, pH, and concentrations of sodium, chloride, and total calcium. Significant negative correlations were found between ionized calcium concentration and concentrations of potassium, BUN, creatinine, and phosphorus. Clinical Implications Most cats with urethral obstruction had a low concentration of ionized calcium. This may contribute to cardiac electrical and mechanical dysfunction in some severely affected cats. Although effects of IV administration of calcium were not evaluated, results of this study strengthen the rationale for its use in cats with urethral obstruction. (J Am Vet Med Assoc 1997;211:1392–1395)
24
McCarthy, S. T., J. P. Younger, and W. G. Owen. "Dynamic, spatially nonuniform calcium regulation in frog rods exposed to light." Journal of Neurophysiology 76, no. 3 (1996): 1991–2004. http://dx.doi.org/10.1152/jn.1996.76.3.1991.
Full textAbstract:
1. In intact rods of the bullfrog, Rana Catesbeiana, that were loaded with Fura-2 by incubation, we made high-resolution measurements of Na:Ca,K exchange currents and measured cytosolic free calcium concentrations during exposure to steps of illumination. The calcium dynamics we observed are indicative of unmanipulated rods because Fura-2 had little effect on calcium buffering within the outer segment. 2. In the dark, the total concentration of calcium within the outer segment, determined by integrating the exchange current, was near 50 microM. The free calcium concentration in darkness was 200-400 nM, indicating that > of = 99% of the internal calcium was bound to buffer molecules or equivalently sequestered. 3. During saturating illumination, the concentration of free calcium near the membrane (assayed by the exchange current) fell more rapidly than the space-averaged free calcium concentration (measured with Fura-2), but both had time courses that were best described by a sum of three exponential terms. The time constants were the same for each assay, but the weighting factors were different. 4. The relationship between the exchange current and space-averaged calcium concentration is consistent with significant concentration gradients within the outer segment resulting from high buffering power, diffusional restrictions, and the fact that all net gain and loss of calcium occurs at the membrane. The data further indicate that effective buffering, and hence calcium mobility, is not uniform within the outer segment. 5. Calcium kinetics were independent of the calcium concentration, indicating that the dominant buffers effectively have a low affinity for calcium (KD >> [Ca2+]dark free). 6. The dynamics of calcium changes and of exchange currents evoked by saturating and nonsaturating illumination are completely predictable from changes in the circulating current. Calcium and current are related by a linear transformation, indicating that calcium fluxes within the outer segment are passive and that buffers equilibrate rapidly. 7. Although calcium concentrations change slowly with respect to changes in the circulating current, both measured and calculated calcium dynamics are well correlated with changes in light adaptation. Responses to test flashes depended weakly on the detailed time course of the adapting stimulus but strongly on the free cytosolic calcium concentration at the time the test flash was delivered.
25
Matamoros, Natalia, María Bernardita Puchulu, Jorge E. Colman Lerner, et al. "Feasibility of increasing calcium content of drinking tap water following quality regulations to improve calcium intake at population level." Gates Open Research 8 (August 29, 2024): 5. http://dx.doi.org/10.12688/gatesopenres.15184.2.
Full textAbstract:
Background Calcium intake is below recommendations in several parts of the world. Improving calcium intake has benefits not only for bone health but also helps to prevent pregnancy hypertension disorders. Calcium concentration of tap water is usually low The aim of the present study was to determine the maximum amount of calcium that can be added to tap water while complying with drinking water Argentine regulations. Methods Tap water samples were collected from the Province of Buenos Aires (Argentina). Physicochemical properties and saturation index were measured. Different incremental concentrations of calcium chloride were added to the experimental aliquots. Results Baseline water had a mean calcium concentration of 22.00 ± 2.54 mg/L, water hardness of 89.9 ± 6.4 mg/L CaCO3, and a saturation index of -1.50 ± 0.11. After the addition of 0.4554 ± 0.0071 g of salt, water hard-ness reached 355.0 ± 7.1 mg/L CaCO3, a calcium concentration of 140.50 ± 2.12 mg/L, and a saturation index -0.53 ± 0.02. Conclusions This study shows that at laboratory level it is feasible to increase calcium concentration of drinking water by adding calcium chloride while complying with national standards. Calcium concentration of drinking tap water could be evaluated and minimum calcium concentration of tap water regulated so as to improve calcium intake in populations with low calcium intake.
26
Matamoros, Natalia, María Bernardita Puchulu, Jorge E. Coleman, et al. "Feasibility of increasing calcium content of drinking tap water following quality regulations to improve calcium intake at population level." Gates Open Research 8 (January 30, 2024): 5. http://dx.doi.org/10.12688/gatesopenres.15184.1.
Full textAbstract:
Background Calcium intake is below recommendations in several parts of the world. Improving calcium intake has benefits not only for bone health but also helps to prevent pregnancy hypertension disorders. Calcium concentration of tap water is usually low The aim of the present study was to determine the maximum amount of calcium that can be added to tap water while complying with drinking water local regulations. Methods Tap water samples were collected from the Province of Buenos Aires (Argentina). Physicochemical properties and saturation index were measured. Different incremental concentrations of calcium chloride were added to the experimental aliquots. Results Baseline water had a mean calcium concentration of 22.00 ± 2.54 mg/L, water hardness of 89.9 ± 6.4 mg/L CaCO3, and a saturation index of -1.50 ± 0.11. After the addition of 0.4554 ± 0.0071 g of salt, water hard-ness reached 355.0 ± 7.1 mg/L CaCO3, a calcium concentration of 140.50 ± 2.12 mg/L, and a saturation index -0.53 ± 0.02. Conclusions This study shows that at laboratory level it is feasible to increase calcium concentration of drinking water by adding calcium chloride while complying with national standards. Calcium concentration of drinking tap water could be evaluated and minimum calcium concentration of tap water regulated so as to improve calcium intake in populations with low calcium intake.
27
Cunningham, J. "Calcium concentration in the dialysate and calcium supplements." Nephrology Dialysis Transplantation 15, no. 90005 (2000): 34–35. http://dx.doi.org/10.1093/ndt/15.suppl_5.34.
Full text
28
Borowiec, Anne-Sophie, Gabriel Bidaux, Natascha Pigat, Vincent Goffin, Sophie Bernichtein, and Thierry Capiod. "Calcium channels, external calcium concentration and cell proliferation." European Journal of Pharmacology 739 (September 2014): 19–25. http://dx.doi.org/10.1016/j.ejphar.2013.10.072.
Full text
29
Al Safi, Hassan. "Effect of polyoxal and Seaweed Extract on some ions in soil, leaves and the early yield of eggplant Solanum melongena L. under protected cultivation." Muthanna Journal for Agricultural Sciences 9, no. 2 (2022): 1–14. http://dx.doi.org/10.52113/mjas04/9.2/12.
Full textAbstract:
This experiment was carried out in Al-Muthanna Governorate in one of the unheated greenhouses dimensions (9 x 54 m) affiliated to experiment station of agricultural research in Al-Bandar area on the side of the Euphrates River, affiliated to the College of Agriculture / University of Al-Muthanna for the winter agricultural season (2021-2022), to study the effect of adding polixal 20-8 at four concentrations (0, 4, 8, 12 ml L-1 ) and spraying seaweed extract (Algaren) at four concentrations (0, 1.5, 3, 4.5 ml L-1 ) on some ions in soil, leaves and the early yield of eggplant cv. Barcelona, The treatments were assigned to experimental following a randomized completely block design (R.C.B.D.). The results showed the significant superiority of adding a polixal (12 ml L -1 ) on the concentration of calcium, sodium and chloride ions in soil and plant, the calcium ion concentration in the soil was 431.8 PPM, the sodium ion concentration was 150.37 PPM, and the chlorine ion concentration was 1869 PPM, while the calcium ion concentration in the leave was 966.1 PPM, the sodium ion concentration was 443.2 PPM, and the chlorine ion concentration was 241.92 PPM, and the early yield is 1.38 kg house -1 Significant differences were also recorded for the results of spraying seaweed extract with a concentration of 4.5 ml L-1 on all studied traits, increasing the calcium concentration, and decreasing the sodium and chloride ions in the soil and plant as the calcium ion concentration in the soil was 395.3 PPM, the sodium ion concentration was 149.29 PPM and the chlorine ion concentration was PPM 2961, while the calcium ion concentration in the plant was PPM 948.4 and the calcium ion concentration in the plant was PPM 948.4. Sodium 431.9 PPM and chlorine ion concentration 241.92 PPM, and the early yield is 1.05 kg house
30
Wadhwani, K. C., H. Levitan, and S. I. Rapoport. "Calcium content of frog sciatic nerve during chronic hypocalcemia and hypercalcemia." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 253, no. 4 (1987): R655—R660. http://dx.doi.org/10.1152/ajpregu.1987.253.4.r655.
Full textAbstract:
We examined the calcium contents of desheathed peripheral nerve, perineurial sheath, and whole sciatic nerve in the frog as a function of the steady-state plasma concentration of ionized calcium. Chronic hypocalcemia was induced by parathyroidectomy and by bathing frogs in a phosphate medium. Chronic hypercalcemia was induced by administering vitamin D3 and by bathing frogs for up to 2 wk in medium containing 50 mM CaCl2. Calcium was measured with a calcium-sensitive electrode and by atomic absorption spectroscopy. The calcium contents (mmol/kg wet wt) in whole nerve, desheathed nerve, and the perineurial sheath varied linearly with slopes of 0.72, 0.71, and 1.72, respectively, with plasma concentration (mM) of ionized calcium, which ranged from 0.3 to 8.0 mM. In the same animals the calcium content in the cerebrum was independent of plasma calcium between 0.5 and 1.5 mM but rose at higher plasma concentrations. Our results indicate that net calcium concentration in the frog peripheral nerve is not regulated during chronic hypocalcemia and hypercalcemia, whereas brain calcium is regulated at plasma calcium concentrations less than 1.5 mM. The lack of calcium regulation in the nerve is attributed to the lack of calcium regulation in the endoneurial compartment.
31
LAM, George S. S., John R. ASPLIN, and Mitchell L. HALPERIN. "Does a high concentration of calcium in the urine cause an important renal concentrating defect in human subjects?" Clinical Science 98, no. 3 (2000): 313–19. http://dx.doi.org/10.1042/cs0980313.
Full textAbstract:
The objective of this study was to evaluate the hypothesis that a high concentration of ionized calcium in the lumen of the medullary collecting duct causes an osmole-free water diuresis. The urine flow rate and osmolality were measured in normal human subjects, as well as in patients with a history of nephrolithiasis who excreted more than 5 mmol of calcium per 24 h. There was an inverse relationship between the concentration of calcium in the urine and the 24 h urine volume both in normal subjects and in patients with a history of nephrolithiasis. When the concentration of calcium in the urine was greater than 5 mmol/l, the urine volume was less than 1 litre per day in the majority of subjects. After 16 h of water deprivation, when the concentration of calcium in the urine was as high as 17 mmol/l (ionized calcium 7.4 mmol/l), urine osmolality was 1258 mOsm/kg of water and the urine flow rate was 0.30 ml/min. We conclude that, although a calcium receptor may be present in the lumen of the medullary collecting duct in human subjects, an extremely high concentration of urinary total and ionized calcium does not cause a clinically important defect in the renal concentrating process.
32
Fakhri, Muhammad, Prive Widya Antika, Arning Wilujeng Ekawati, and Nasrullah Bai Arifin. "Growth, Pigment and Protein Production of Spirulina platensis under different Ca(NO3)2 concentrations." Journal of Aquaculture and Fish Health 9, no. 1 (2020): 38. http://dx.doi.org/10.20473/jafh.v9i1.15769.
Full textAbstract:
Spirulina platensis is a filamentous cyanobacterium that has been commerically used for fish feed and human food supplement. Low-cost production of Spirulina is needed when considering large-scale culture especially for industrial purposes. The aim of this study was to explain the effect of calcium nitrate (Ca(NO3)2) on growth, biomass, pigment, and protein production of S. platensis and to determine the best calcium nitrate concentration for Spirulina production.The microalgae was cultured at four calcium nitrate concentrations (1, 1.5, 2.0 and 2.5 g/L) with salinity of 15 ppt, constant light intensity of 4,000 lux and photoperiod of 24:0 light:dark cycles for 4 days. The results showed that different calcium nitrate concentrations remarkably affected the growth, biomass production, pigment and protein content of S. platensis (p<0.05). The highest specific growth rate of 0.721 day-1 and biomass concentration of 1.512 g/Lwere achieved at calcium nitrate concentration of 2.5 g/L. Moreover, the algae had the highest chlorophyll-a, carotenoid and protein content at 2.5 g L-1. Increasing calcium nitrate concentration from 1 to 2.5 g/L led to an increase in biomass, pigment and protein production of S. platensis. However, there was no significant difference between 2 and 2.5 g L-1 calcium nitrate concentrations. We suggest that 2-2.5 g/L Ca(NO3)2 concentration can be used profitably for S. platensis production.
33
Neufeld, D., and J. Cameron. "EFFECT OF THE EXTERNAL CONCENTRATION OF CALCIUM ON THE POSTMOULT UPTAKE OF CALCIUM IN BLUE CRABS (CALLINECTES SAPIDUS)." Journal of Experimental Biology 188, no. 1 (1994): 1–9. http://dx.doi.org/10.1242/jeb.188.1.1.
Full textAbstract:
The rate of calcium uptake in blue crabs (Callinectes sapidus Rathbun) acclimated to 2 sea water with a calcium concentration of 1.4 mmol l-1 was dependent on the magnitude and direction of the electrochemical gradient for calcium. When transferred to water with a high calcium concentration (6 mmol l-1), the electrochemical gradient for calcium favoured diffusive influx, and calcium uptake and apparent H+ excretion increased by approximately 50 %. When transferred to water with a low calcium concentration (0.10 mmol l-1), where the electrochemical gradient for calcium strongly favoured diffusive efflux, calcium uptake ceased but apparent H+ excretion continued at a reduced rate. Crabs regulated the free calcium concentration in their blood at approximately 8 mmol l-1 when the external concentration of calcium was 1.4 mmol l-1 or higher, but the concentration of free calcium in the blood decreased to 5.6 and 4.6 mmol l-1, respectively, at external concentrations of calcium of 0.25 and 0.10 mmol l-1. Crabs transferred to water with 0.10 mmol l-1 calcium for the first 2 days after moult accumulated only 2.5 g calcium kg-1 wet mass, about one-quarter of the mass normally accumulated. Seawater-acclimated crabs transferred to 2 salinity at 1 day postmoult took up calcium at a reduced rate, indicating that a period of acclimation is necessary for a component of the active transport system to increase its capacity, for diffusive efflux to be reduced, or for both to occur.
34
Newsom, Leslie, Brian L. Erstad, Paul Z. Nakazato, and John A. Daller. "Falsely Decreased Total Serum Calcium Concentration Associated With Iron Dextran Injection." Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy 15, no. 6 (1995): 789–92. http://dx.doi.org/10.1002/j.1875-9114.1995.tb02899.x.
Full textAbstract:
We cared for a patient in whom iron dextran administration interfered with the determination of total serum calcium concentration. An unexpected elevation in serum phosphorus concentration also occurred after the iron dextran infusion. A MEDLINE search from 1966 to present was conducted, and the manufacturer of the iron dextran was contacted for information related to these findings. Several drugs and diseases were found that may decrease serum calcium and increase phosphorus concentrations. We found one anecdotal citation of iron dextran interfering with serum calcium concentrations, but no reports of interference with serum phosphorus concentrations. Doses of iron dextran in excess of 250 mg may cause a false decrease in total calcium concentration more than 4 hours after the infusion is completed. A false increase in serum phosphorus concentrations after the infusion requires further investigation.
35
Mine, T., I. Kojima, and E. Ogata. "Role of calcium fluxes in the action of glucagon on glucose metabolism in rat hepatocytes." American Journal of Physiology-Gastrointestinal and Liver Physiology 265, no. 1 (1993): G35—G42. http://dx.doi.org/10.1152/ajpgi.1993.265.1.g35.
Full textAbstract:
The aim of the present study was to assess the role of calcium fluxes in the action of glucagon on glycogenolysis and gluconeogenesis in isolated rat hepatocytes. Calcium influx was blocked by two ways: by use of the compound tetramethrin and by reduction of extracellular calcium to 1 microM. The minimal concentration of tetramethrin that inhibited glucagon-mediated calcium entry was 7.5 x 10(-7) M. In the presence of 7.5 x 10(-7) M tetramethrin, glucagon-induced glycogenolysis was markedly attenuated when glucagon concentration was 10(-9) M or higher. In contrast, tetramethrin had no effect on glucogenolysis evoked by lower concentrations of glucagon. Similarly, tetramethrin greatly reduced gluconeogenesis induced by high concentrations of glucagon without affecting the effect of low concentrations of glucagon. The same results were obtained in the presence of 1 microM extracellular calcium. To abolish glucagon-induced elevation of cytoplasmic free calcium concentration, we heavily loaded quin2 into hepatocytes. In these cells, glycogenolysis evoked by low concentrations of glucagon was completely abolished. Glycogenolysis caused by high concentrations of glucagon was markedly inhibited. These results indicate that glucagon action on hepatic glucose metabolism is mediated by two different mechanisms, which depend on concentrations of glucagon.
36
Lee, Sean. "Investigating the Feasibility of Xylitol and Gelatin for Controlled Release System in Drug Delivery using Calcium Alginate." Journal of International Research in Medical and Pharmaceutical Sciences 19, no. 3 (2024): 52–69. http://dx.doi.org/10.56557/jirmeps/2024/v19i38890.
Full textAbstract:
Calcium Alginate-based beads have been recognized to have high potential for pharmaceutical applications thanks to their ease of use and biocompatibility. This study aims to investigate how xylitol and gelatin could be used for a controlled drug delivery system and how to manipulate such a delivery system. For the study, calcium alginate beads were synthesized using two different calcium compounds: calcium lactate (CL) and calcium chloride (CC). Varying concentrations of the calcium compounds in the beads were prepared to measure their effects on their characteristics, such as size, weight, strength, and, most importantly, the diffusion rate. The study attempted to manipulate the diffusion rates by incorporating xylitol and gelatin into the calcium alginate membrane. A comparative analysis revealed that CC and CL affected the beads differently. For instance, bead size increased with CC concentration up to 5%, after which it decreased, while CL showed a more consistent decrease in size as concentration increased. Weight generally decreased with higher concentrations of both CC and CL, but the reduction was more pronounced with CL. The popping force increased with CC concentration but had a non-linear relationship with CL, reaching around 7% concentration before decreasing. The study also examined the percentage change in weight after 48 hours of drying. For smaller beads (3mm), the weight change decreased with higher CC concentration, but for larger beads (7.05mm), the trend reversed, showing an increase in weight change at higher concentrations. Similar patterns were observed for CL, with weight change initially decreasing but increasing with higher concentrations. Our diffusion studies found that the xylitol concentration generally enhanced diffusion rates, with CL beads showing a greater initial diffusion than CC beads. In contrast, gelatin concentration has less predictable effects on diffusion rates. For CL beads, more gelatin results in less dye diffusion, suggesting that gelatin may impact the initial release of dye from the beads.
37
Hu, Qizhi, and Zekai Wang. "Experimental Study on Microbial Solidification of Gravel-Containing Silty Clay under Different Calcium Sources." Geofluids 2022 (September 23, 2022): 1–11. http://dx.doi.org/10.1155/2022/7321869.
Full textAbstract:
Crushed silty clay is widely distributed in engineering foundations. Because of its local hardness and uneven soil distribution, it is not a good foundation material. Based on microbial solidification technology, microbial solidification tests of silty clay containing crushed stone were carried out by selecting cementing liquids with different calcium sources to study the effect of the calcium source on the solidification effect. With Pasteurella as the main solidified bacterial solution, calcium chloride, calcium acetate, and calcium gluconate were mixed into urea to prepare cementing solutions with different calcium sources at concentrations of 0.6, 1.0, and 1.4 mol/L. Microbial solidification tests were carried out under different calcium source concentrations, the calcium carbonate formation of the samples after solidification was examined, and unconfined compressive strength and triaxial tests were conducted. When calcium chloride and calcium acetate were used to solidify the clay, the solidification strength gradually decreased with the increase in the concentration, while the solidification strength of calcium gluconate was the highest at 1.0 mol/L. When calcium chloride with a concentration of 0.6 mol/L was used as the calcium source, the curing effect was the best. The internal friction angle and cohesion of the triaxial test were increased by 35.19% and 99.1%, respectively, and the unconfined compressive strength was increased by 37.94%. The yield ratio was 3.76%. The concentration of 1.0 mol/L was the best concentration of calcium gluconate as the calcium source, and the reinforcement effect was slightly less than that of 0.6 mol/L calcium chloride.
38
Lapre, J. A., H. T. De Vries, and R. van der Meer. "Dietary calcium phosphate inhibits cytotoxicity of fecal water." American Journal of Physiology-Gastrointestinal and Liver Physiology 261, no. 6 (1991): G907—G912. http://dx.doi.org/10.1152/ajpgi.1991.261.6.g907.
Full textAbstract:
The effects of dietary steroid and CaHPO4 supplementation on the solubility of bile acids and cytotoxicity of fecal water were studied in rats. Dietary steroid supplementation increased the bile acid concentration of both feces and fecal water. CaHPO4 supplementation produced a slight increase in total fecal bile acid concentration but resulted in a drastic decrease in soluble bile acid concentration. Cytotoxicity of fecal water on control and steroid-supplemented diets decreased with CaHPO4 supplementation analogous to the decrease in soluble bile acid concentration. The concentrations of precipitated Ca and Pi were highly correlated (r greater than 0.90) with the concentration of precipitated bile acids and with inhibition of cytotoxicity. However, there was no significant correlation between the logarithms of soluble calcium and soluble bile acids, indicating that solubility of bile acids is not determined by soluble calcium. Concentrations of calcium and phosphate in fecal water indicated the formation of insoluble calcium phosphate in the intestine. Thus dietary CaHPO4 causes a decrease in soluble bile acid concentration, which is probably due to the formation of an insoluble bile acid calcium phosphate complex. Consequently, cytotoxicity of fecal water is inhibited, which might have implications for the protective effect of dietary calcium with regard to colonic cancer in humans.
39
Eich, Torsten, Magnus Ståhle, Bengt Gustafsson, et al. "Calcium." Cell Transplantation 27, no. 7 (2018): 1031–38. http://dx.doi.org/10.1177/0963689718779350.
Full textAbstract:
Background: Effective digestive enzymes are crucial for successful islet isolation. Supplemental proteases are essential because they synergize with collagenase for effective pancreatic digestion. The activity of these enzymes is critically dependent on the presence of Ca2+ ions at a concentration of 5–10 mM. The present study aimed to determine the Ca2+ concentration during human islet isolation and to ascertain whether the addition of supplementary Ca2+ is required to maintain an optimal Ca2+ concentration during the various phases of the islet isolation process. Methods: Human islets were isolated according to standard methods and isolation parameters. Islet quality control and the number of isolations fulfilling standard transplantation criteria were evaluated. Ca2+ was determined by using standard clinical chemistry routines. Islet isolation was performed with or without addition of supplementary Ca2+ to reach a Ca2+ of 5 mM. Results: Ca2+ concentration was markedly reduced in bicarbonate-based buffers, especially if additional bicarbonate was used to adjust the pH as recommended by the Clinical Islet Transplantation Consortium. A major reduction in Ca2+ concentration was also observed during pancreatic enzyme perfusion, digestion, and harvest. Additional Ca2+ supplementation of media used for dissolving the enzymes and during digestion, perfusion, and harvest was necessary in order to obtain the concentration recommended for optimal enzyme activity and efficient liberation of a large number of islets from the human pancreas. Conclusions: Ca2+ is to a large extent consumed during clinical islet isolation, and in the absence of supplementation, the concentration fell below that recommended for optimal enzyme activity. Ca2+ supplementation of the media used during human pancreas digestion is necessary to maintain the concentration recommended for optimal enzyme activity. Addition of Ca2+ to the enzyme blend has been implemented in the standard isolation protocols in the Nordic Network for Clinical Islet Transplantation.
40
Sasaki, Koichi, Hideharu Shintani, Junpei Itoh, Takuji Kamogawa, and Yousei Kajihara. "Effect of Calcium in Assay Medium on DValue of Bacillus stearothermophilus ATCC 7953 Spores." Applied and Environmental Microbiology 66, no. 12 (2000): 5509–13. http://dx.doi.org/10.1128/aem.66.12.5509-5513.2000.
Full textAbstract:
ABSTRACT The D value of commercial biological indicator spore strips using Bacillus stearothermophilus ATCC 7953 was increased by higher calcium concentrations in assay media. The calcium concentration in assay media varied among the manufacturers. The calcium concentration in assay media is an important factor to consider to minimize the variation of D value.
41
Fahd, Alsalleeh, Stephenson Lane., Lyons Nickolas., Young Ashley., and Williams Stetson. "Human Periodontal Ligament Cells Response to Commercially Available Calcium Hydroxide Pastes." International Journal of Dentistry and Oral Science (IJDOS) 1, no. 1 (2014): 6–9. https://doi.org/10.19070/2377-8075-140002.
Full textAbstract:
Several studies have shown that calcium hydroxidebased medicaments have a cytotoxic effect on human cells. The purpose of this study was to evaluate the cytoxicity of several calcium hydroxideproducts on periodontal ligament (PDL) cells. Calcium hydroxide powder (Avantor Performance Materials Inc.), Calasept® (Nordiska Dental AB), Metapaste® (Meta Biomed Co., Ltd.), Vitapex® (Neo Dental International Inc.), Ultracal® (Ultradent Products, Inc.), and Pulpdent® (Pulpdent Corporation) products were tested. PDL cells were exposed to various concentrations of calcium hydroxidefrom each product (1.0, 0.5, 0.25, and 0.125 mg/mL). Cell viability was measured after 24 h and 48 h by Cell Proliferation Assay. All materials tested had a more toxic effect on PDL cells after 48 h.At 24 and 48 h, Metapaste® was the most toxic regardless of concentrations used. Products with a1.0 and 0.5 mg/mL concentration hadstatistically significant more cytotoxic effectswhen compared to the negative control. Pure calcium hydroxide and Calacept® induced 35% cell death at a 1 mg/mL concentration and 15-20% cell death at 0.5, 0.25, and 0.125 mg/mL after 24 h. Pulpdent® and Ultracal® induced 30-35% cell death at a 1 mg/mL concentration and its effect diminished at 0.25 and 0.125 mg/mL at 24 h. The Vitapex® preparation induced 20% PDL cell death at 24 h regardless of the concentration and was the least toxic significantly at 1 mg/ mL compared to other brands, except Pulpdent®, at the same concentration at 24 h.All calcium hydroxideproducts showed evidence of cytoxicity on PDL cells, with Metapaste being the most cytotoxic. The cytotoxicity was related to concentration and exposure time. Pulpdent® and Ultracal® had excellent biocompatibility at lower concentrations.
42
Nóbrega, Diego Figueiredo, Tarcísio Jorge Leitão, Jaime Aparecido Cury, and Livia Maria Andaló Tenuta. "Fluoride Binding to Dental Biofilm Bacteria: Synergistic Effect with Calcium Questioned." Caries Research 53, no. 1 (2018): 10–15. http://dx.doi.org/10.1159/000488598.
Full textAbstract:
It has been suggested that fluoride binding to dental biofilm is enhanced when more bacterial calcium binding sites are available. However, this was only observed at high calcium and fluoride concentrations (i.e., when CaF2 precipitation may have occurred). We assessed fluoride binding to Streptococcus mutans pellets treated with calcium and fluoride at concentrations allowing CaF2 precipitation or not. Increasing calcium concentration resulted in a linear increase (p < 0.01) in fluoride concentration only in the pellets in which CaF2 precipitated. The results suggest that CaF2 precipitation, rather than bacterially bound fluoride, is responsible for the increase in fluoride binding to dental biofilm with the increase in calcium availability.
43
Alteraifi, A. M., and D. V. Zhelev. "Transient increase of free cytosolic calcium during neutrophil motility responses." Journal of Cell Science 110, no. 16 (1997): 1967–77. http://dx.doi.org/10.1242/jcs.110.16.1967.
Full textAbstract:
The release of free cytosolic calcium is a secondary messenger for many cell functions. Here we study the coupling between the release of intracellular calcium and motility responses of the human neutrophil. Two groups of motility responses are studied: motility responses in the presence of adhesion, such as cell crawling and phagocytosis, and motility responses ‘in suspension’, such as pseudopod formation. The motility responses are stimulated by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP) and the release of calcium is monitored by measuring the fluorescence from fluo-3. fMLP induces a single release of free cytosolic calcium both in suspended cells and in crawling cells. Calcium release is a threshold process where the number of cells releasing calcium is dependent on the chemoattractant concentration while the amount of released calcium is not. For suspended cells the threshold fMLP concentration for calcium release is in the order of 10(−7) M, while for crawling cells it is in the order of 5x10(−9) M. The smaller value of the threshold fMLP concentration for crawling cells compared to that for suspended cells suggests that bound adhesion receptors are involved in the calcium release. The threshold fMLP concentration for suspended cells is also larger than the minimum fMLP concentration (in the order of 10(−10) M) for initiating pseudopod formation. So, there is a range of fMLP concentrations where pseudopod formation occurs without calcium release. To explore this relationship further, pseudopod extension and calcium release are stimulated many times in a single cell by using fMLP concentrations above the threshold. The result is that calcium release is desensitized by fMLP while pseudopod extension is not. All the results taken together suggest that the release of free cytosolic calcium and the rearrangement of the F-actin network during motility follow different signaling pathways.
44
Jean, Guillaume, and Charles Chazot. "Individualizing the dialysate calcium concentration." Current Opinion in Nephrology and Hypertension 24, no. 6 (2015): 538–45. http://dx.doi.org/10.1097/mnh.0000000000000176.
Full text
45
Niu, Xufeng, Rui Fan, Feng Tian, et al. "Calcium concentration dependent collagen mineralization." Materials Science and Engineering: C 73 (April 2017): 137–43. http://dx.doi.org/10.1016/j.msec.2016.12.079.
Full text
46
Jansen, I., and L. Edvinsson. "Effects of Extracellular Calcium and of the Calcium Entry Blockers Flunarizine and Nimodipine on Contractile Responses in Human Temporal Arteries." Cephalalgia 6, no. 4 (1986): 235–40. http://dx.doi.org/10.1046/j.1468-2982.1986.0604235.x.
Full textAbstract:
Contraction induced by 124 mM potassium followed the depolarization of smooth-muscle cells and activation of potential-operated calcium channels in human temporal arteries. The contraction elicited consisted of two phases, one rapid and one slowly developing stable phase; both were affected by the two calcium entry blockers flunarizine and nimodipine but at significantly different concentrations. In calcium-free medium 124 mM potassium resulted in a weak contraction. Addition of calcium caused a concentration-dependent contraction that was attenuated by the calcium entry blockers at concentrations comparable to those inhibiting the second phase. The results suggested that in human temporal arteries flunarizine and nimodipine act as calcium entry blockers; there was good correlation with the therapeutic plasma concentration for nimodipine but not for flunarizine.
47
Howell, John N., and Hans Oetliker. "Effects of repetitive activity, ruthenium red, and elevated extracellular calcium on frog skeletal muscle: implications for t-tubule conduction." Canadian Journal of Physiology and Pharmacology 65, no. 4 (1987): 691–96. http://dx.doi.org/10.1139/y87-114.
Full textAbstract:
In this report we review evidence that indicates that experimental elevation of t-tubular calcium can lead to failure of action potential propagation within the t system and we present some new evidence suggesting that t-tubular calcium concentration may rise during repetitive activity. The evidence for t-tubular conduction failure consists of comparisons of the effects of high calcium and of ruthenium red on excitation and excitation–contraction coupling as well as morphological observations of wavy myofibrils in the axial core of fibers contracting tetanically in solutions containing elevated calcium concentrations. Evidence for elevation of t-tubular calcium concentration during repetitive activity comes from the following. During twitches, the early, large birefringence signal and force development arc delayed in onset if the extracellular calcium and (or) potassium concentrations are above normal or if the fiber has been stimulated tetanically just prior to the test twitch. The delays that occur in twitches following tetanic contractions are attenuated when the extracellular and, therefore, the t-tubular calcium concentration is buffered with citrate.
48
Lincoln, S. D., and V. M. Lane. "Serum ionized calcium concentration in clinically normal dairy cattle, and changes associated with calcium abnormalities." Journal of the American Veterinary Medical Association 197, no. 11 (1990): 1471–74. http://dx.doi.org/10.2460/javma.1990.197.11.1471.
Full textAbstract:
Summary Serum ionized calcium (ICa) concentration was determined in 141 clinically normal dairy cattle by use of a direct-measuring calcium ion-selective electrode instrument. Mean serum ICa concentration 2 hours after blood withdrawal was 4.59 mg/dl; range varied from 3.79 to 5.25 mg/dl. Regression analysis indicated a high degree of correlation between ICa and serum total calcium concentrations if serum stored at 23 C was analyzed within 12 hours after blood withdrawal. Abnormal ICa concentration was detected in 19 of 85 dairy cows that were affected with various pathologic conditions. All 19 cows had hypocalcemia (n = 13 with parturient hypocalcemia, 4 with hypomagnesemic tetany, and 2 with renal disease). In all cases, the ICa concentration clearly related to the clinical manifestation of disease and the functional status of the cow's calcium metabolism.
49
Portale, A. A., E. T. Lonergan, D. M. Tanney, and B. P. Halloran. "Aging alters calcium regulation of serum concentration of parathyroid hormone in healthy men." American Journal of Physiology-Endocrinology and Metabolism 272, no. 1 (1997): E139—E146. http://dx.doi.org/10.1152/ajpendo.1997.272.1.e139.
Full textAbstract:
We examined the effect of aging on the relationship between the concentrations of blood ionized calcium and of serum parathyroid hormone (PTH) in 22 healthy men [9 elderly (age 74 +/- 2 yr) and 13 young (age 39 +/- 1 yr)] in whom the glomerular filtration rate was > 70 ml/min. Throughout a 24-h period, serum concentrations of PTH in the elderly men were twice those in the young men, whereas blood ionized calcium did not differ between the two groups. With intravenous infusion of calcium gluconate, the minimum PTH concentration was two- to threefold higher in the elderly men. With infusion of NaEDTA. the maximum PTH concentration was 20% higher in the elderly men. The calcium set point for PTH release was higher in the elderly than in the young men (4.71 +/- 0.04 vs. 4.54 +/- 0.03 mg/dl, respectively, P < 0.005). In these healthy men, the age-related increase in serum PTH could not be attributed to a sustained decrease in concentration of either blood ionized calcium or 1,25-hydroxyvitamin D. These findings suggest that, with aging, the relationship between calcium and PTH is altered such that at any given level of calcium, the concentration of PTH is higher.
50
NEUFELD, DOUGLAS S., and JAMES N. CAMERON. "Postmoult Uptake of Calcium by the Blue Crab (Callinectes Sapidus) in Water of low Salinity." Journal of Experimental Biology 171, no. 1 (1992): 283–99. http://dx.doi.org/10.1242/jeb.171.1.283.
Full textAbstract:
After moulting, blue crabs (Callinectes sapidus) acclimated to a salinity of 2‰ were able to calcify as rapidly and accumulate as much calcium as crabs in sea water. Immediately after moult, the total masses of calcium, magnesium and strontium present in the whole body were 4.6, 15.6 and 3.0%, respectively, of their intermoult values. During the time of most rapid calcification, calcium uptake was 5.4±1.4mmoll−1, which is comparable to the maximum rate found in seawater-acclimated crabs. The concentrations of bound and free calcium in the blood changed very little with acclimation salinity, remaining at approximately 3 and 8mmoll−1, respectively, both during intermoult and 1 day postmoult. Free calcium changed relatively little through the moult cycle, varying between 6.9 and 8.1mmoll−1, but bound calcium rose to a peak of 6.4mmoll−1 prior to moult then dropped to 2.6mmoll−1 after moult, concurrent with a decrease of approximately 80% in the protein concentration of the blood. The concentration of total magnesium in the blood increased from a premoult low of 9.0mmoll−1 to a postmoult high of 11.7mmoll−1 and remained elevated throughout the period of rapid mineralization. During the postmoult period of rapid calcium uptake, the internal-to-external concentration ratio for total calcium was 6.6 to 1. The activity ratio, however, was only 2.5 to 1 because 28% of the calcium in the blood was bound to protein, and because the lower ionic strength of the medium resulted in a 2.5-fold higher activity coefficient for the water compared to blood. The transepithelial potential at postmoult (−5.4±0.7mV) was significantly more negative than at intermoult (−3.1±0.6mV). In artificial 2‰ sea water, the transepithelial potential (−9.3±0.7mV) was higher than the equilibrium potential for calcium (−12.0±0.5mV), implicating active transport in the uptake of calcium.