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Calcium carbonate ReagentPlus®; CAS Number: 471-34-1; EC Number: 207-439-9; Linear Formula: CaCO3; find Sigma-Aldrich-C6763 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich

Calcium carbonate ReagentPlus , SAFC Yes 471-34-1

Calcium carbonate

Kinetics of calcium carbonate decomposition.

Polymorphs calcium carbonate on temperature reaction.

Permeability of porous ceramic based on calcium carbonate as pore generating agent.

Calcium carbonate nanoparticles as cancer drug delivery system.

Aluminum release from microwave-assisted reaction of coal fly ash with calcium carbonate.

Opposite particle size effect on amorphous calcium carbonate crystallization in water and during heating in air.

Phosphate binders (calcium-based and calcium-free) are recommended to lower serum phosphate and prevent hyperphosphataemia in patients with chronic kidney disease, but their effects on mortality and cardiovascular outcomes are unknown. We aimed to update our meta-analysis on the effect of calcium-based versus non-calcium-based phosphate binders on mortality in patients with chronic kidney disease. We did a systematic review of articles published in any language after Aug 1, 2008, up until Oct 22, 2012, by searching Medline, Embase, International Pharmaceutical Abstracts, Cochrane Central Register of Controlled Trials, and Cumulative Index to Nursing and Allied Health Literature. We included all randomised and non-randomised trials that compared outcomes between patients with chronic kidney disease taking calcium-based phosphate binders with those taking non-calcium-based binders. Eligible studies, determined by consensus with predefined criteria, were reviewed, and data were extracted onto a standard form. We combined data from randomised trials to assess the primary outcome of all-cause mortality using the DerSimonian and Laird random effects model. Our search identified 847 reports, of which eight new studies (five randomised trials) met our inclusion criteria and were added to the ten (nine randomised trials) included in our previous meta-analysis. Analysis of the 11 randomised trials (4622 patients) that reported an outcome of mortality showed that patients assigned to non-calcium-based binders had a 22% reduction in all-cause mortality compared with those assigned to calcium-based phosphate binders (risk ratio 0·78, 95% CI 0·61-0·98). Non-calcium-based phosphate binders are associated with a decreased risk of all-cause mortality compared with calcium-based phosphate binders in patients with chronic kidney disease. Further studies are needed to identify causes of mortality and to assess whether mortality differs by type of non-calcium-based phosphate binder. None.

Effect of calcium-based versus non-calcium-based phosphate binders on mortality in patients with chronic kidney disease: an updated systematic review and meta-analysis.

Polysaccharides and proteoglycans in calcium carbonate-based biomineralization.

Clinical outcomes of the Women's Health Initiative (WHI) calcium plus vitamin D supplementation trial have been reported during 7.0 years of active intervention. We now report outcomes 4.9 years after the intervention stopped and cumulative findings. Postmenopausal women (N=36,282) were randomized; postintervention follow-up continued among 29,862 (86%) of surviving participants. Primary outcomes were hip fracture and colorectal cancer. Breast cancer, all cancers, cardiovascular disease (CVD), and total mortality were predetermined major study outcomes. Hip fracture incidence was comparable in the supplement and the placebo groups, postintervention hazard ratio (HR)=0.95, 95% confidence interval (95% CI: 0.78, 1.15) and overall HR=0.91 (95% CI: 0.79, 1.05). Overall, colorectal cancer incidence did not differ between randomization groups, HR=0.95 (95% CI: 0.80, 1.13). Throughout, there also was no difference in invasive breast cancer, CVD, and all-cause mortality between groups. In subgroup analyses, the invasive breast cancer effect varied by baseline vitamin D intake (p=0.03 for interaction). Women with vitamin D intakes >600 IU/d, had an increased risk of invasive breast cancer, HR=1.28 (95% CI; 1.03, 1.60). Over the entire study period, in post hoc analyses, the incidence of vertebral fractures, HR=0.87 (95% CI: 0.76, 0.98) and in situ breast cancers, HR=0.82 (95% CI: 0.68, 0.99) were lower among women randomized to supplementation. After an average of 11 years, calcium and vitamin D supplementation did not decrease hip fracture or colorectal cancer incidence. Exploratory analyses found lower vertebral fracture and in situ breast cancer incidence in the supplement users. There was no effect on CVD or all-cause mortality.

Calcium plus vitamin D supplementation and health outcomes five years after active intervention ended: the Women's Health Initiative.

An organic matrix consisting of a protein-polysaccharide complex is generally accepted as an important medium for the calcification process. While the role this "calcified organic matrix" plays in the calcification process has long been appreciated, the complex mixture of proteins that is induced and assembled during the mineral phase of calcification remains uncharacterized in many organisms. Thus, we investigated organic matrices from the calcitic sclerites of a soft coral, Sinularia sp., and used a proteomic approach to identify the functional matrix proteins that might be involved in the biocalcification process. We purified eight organic matrix proteins and performed in-gel digestion using trypsin. The tryptic peptides were separated by nano-liquid chromatography (nano-LC) and analyzed by tandem mass spectrometry (MS/MS) using a matrix-assisted laser desorption/ionization (MALDI) - time-of-flight-time-of-flight (TOF-TOF) mass spectrometer. Periodic acid Schiff staining of an SDS-PAGE gel indicated that four proteins were glycosylated. We identified several proteins, including a form of actin, from which we identified a total of 183 potential peptides. Our findings suggest that many of those peptides may contribute to biocalcification in soft corals.

Analysis of the proteinaceous components of the organic matrix of calcitic sclerites from the soft coral Sinularia sp.

To examine whether combined vitamin D and calcium supplementation improves insulin sensitivity, insulin secretion, β-cell function, inflammation and metabolic markers. 6-month randomized, placebo-controlled trial. Ninety-five adults with serum 25-hydroxyvitamin D [25(OH)D] ≤55 nmol/L at risk of type 2 diabetes (with prediabetes or an AUSDRISK score ≥15) were randomized. Analyses included participants who completed the baseline and final visits (treatment n = 35; placebo n = 45). Daily calcium carbonate (1,200 mg) and cholecalciferol [2,000-6,000 IU to target 25(OH)D >75 nmol/L] or matching placebos for 6 months. Insulin sensitivity (HOMA2%S, Matsuda index), insulin secretion (insulinogenic index, area under the curve (AUC) for C-peptide) and β-cell function (Matsuda index x AUC for C-peptide) derived from a 75 g 2-h OGTT; anthropometry; blood pressure; lipid profile; hs-CRP; TNF-α; IL-6; adiponectin; total and undercarboxylated osteocalcin. Participants were middle-aged adults (mean age 54 years; 69% Europid) at risk of type 2 diabetes (48% with prediabetes). Compliance was >80% for calcium and vitamin D. Mean serum 25(OH)D concentration increased from 48 to 95 nmol/L in the treatment group (91% achieved >75 nmol/L), but remained unchanged in controls. There were no significant changes in insulin sensitivity, insulin secretion and β-cell function, or in inflammatory and metabolic markers between or within the groups, before or after adjustment for potential confounders including waist circumference and season of recruitment. In a post hoc analysis restricted to participants with prediabetes, a significant beneficial effect of vitamin D and calcium supplementation on insulin sensitivity (HOMA%S and Matsuda) was observed. Daily vitamin D and calcium supplementation for 6 months may not change OGTT-derived measures of insulin sensitivity, insulin secretion and β-cell function in multi-ethnic adults with low vitamin D status at risk of type 2 diabetes. However, in participants with prediabetes, supplementation with vitamin D and calcium may improve insulin sensitivity. Australian New Zealand Clinical Trials Registry ACTRN12609000043235.

Effects of combined calcium and vitamin D supplementation on insulin secretion, insulin sensitivity and β-cell function in multi-ethnic vitamin D-deficient adults at risk for type 2 diabetes: a pilot randomized, placebo-controlled trial.

Arsenic contamination of floodplain soils is extensive and additional fresh arsenic inputs to the pedosphere from human activities are ongoing. We investigate the cumulative effects of repetitive soil redox cycles, which occur naturally during flooding and draining, on a calcareous fluvisol, the native microbial community and arsenic mobility following a simulated contamination event. We show through bioreactor experiments, spectroscopic techniques and modelling that repetitive redox cycling can decrease arsenic mobility during reducing conditions by up to 45%. Phylogenetic and functional analyses of the microbial community indicate that iron cycling is a key driver of observed changes to solution chemistry. We discuss probable mechanisms responsible for the arsenic immobilisation observed in-situ. The proposed mechanisms include, decreased heterotrophic iron reduction due to the depletion of labile particulate organic matter (POM), increases to the proportion of co-precipitated vs. aqueous or sorbed arsenic with α-FeOOH/Fe(OH)3 and potential precipitation of amorphous ferric arsenate.

The impact of oscillating redox conditions: arsenic immobilisation in contaminated calcareous floodplain soils.

In this work, we aimed at adsorbing the oligo-sugars of prehydrolysis liquor on precipitated calcium carbonate (PCC) to produce modified PCC. The results showed that the adsorptions of oligo-sugars, lignin and furfural were greater on porous PCC (PCC2) than on nano-sized PCC (PCC1) due to the larger surface area of PCC2. The adsorption reached its maximum in 5 h on PCC1, but it gradually increased on PCC2 due to the diffusion of oligo-sugars and lignin into the pores of PCC2. Also, the experimental isotherm and kinetic results were well fitted into Langmuir and pseudo-second order models, respectively. The adsorption was greater at a lower temperature (i.e. 40°C) and pH (i.e. 7). Alternatively, cationic poly acrylamide (CPAM) was added to the PHL/PCC system, which led to more promising results (than that to PHL/PCC system) with the maximum lignocelluloses adsorption of 0.36 g/g on PCC2, among which 0.22 g/g was oligo-sugars.

Adsorption of lignocelluloses of pre-hydrolysis liquor on calcium carbonate to induce functional filler.

Vitamin D insufficiency may increase the risk for cardio metabolic disturbances in patients with primary hyperparathyroidism (PHPT). To analyze the vitamin D status and indices of the metabolic syndrome in PHPT patients and the effect of vitamin D supplementation after parathyroid adenomectomy (PTX). Double-blinded, randomized clinical trial (ClinicalTrials.gov identifier: NCT00982722) performed at Karolinska University Hospital, Sweden, April 2008 to November 2011. One hundred and fifty consecutive patients with PHPT (119 women) were randomized after PTX, 75 to oral treatment with calcium carbonate 1000 mg daily and 75 to calcium carbonate 1000 mg and cholecalciferol 1600 IU daily over 12 months. Changes in metabolic profile and ambulatory blood pressure (BP) were analyzed. Main outcome measures were changes in metabolic factors, BP, and body composition. The 25-hydroxyvitamin D (25-OH-D)-level was <50 nmol/l in 76% of the patients before PTX. After PTX, glucose, insulin, and IGF1 decreased, while the 25-OH-D and the IGF-binding protein 1 increased and remained unchanged at follow-up after study medication. One year of vitamin D supplementation resulted in lower parathyroid hormone (PTH) (40 (34-52) vs 49 (38-66) ng/l) and higher 25-OH-D (76 (65-93) vs 49 (40-62) nmol/l; P<0.05). Other laboratory parameters were stable compared with after PTX. Systolic BP decreased and total bone mineral content increased in both groups. Except for the lowering of the PTH level, no additive effect of vitamin D supplementation was seen. However, PTX proved effective in reducing insulin resistance.

Primary hyperparathyroidism and metabolic risk factors, impact of parathyroidectomy and vitamin D supplementation, and results of a randomized double-blind study.

Hierarchical composite materials design in biological exoskeletons achieves penetration resistance through a variety of energy-dissipating mechanisms while simultaneously balancing the need for damage localization to avoid compromising the mechanical integrity of the entire structure and to maintain multi-hit capability. Here, we show that the shell of the bivalve Placuna placenta (~99 wt% calcite), which possesses the unique optical property of ~80% total transmission of visible light, simultaneously achieves penetration resistance and deformation localization via increasing energy dissipation density (0.290 ± 0.072 nJ μm(-3)) by approximately an order of magnitude relative to single-crystal geological calcite (0.034 ± 0.013 nJ μm(-3)). P. placenta, which is composed of a layered assembly of elongated diamond-shaped calcite crystals, undergoes pervasive nanoscale deformation twinning (width ~50 nm) surrounding the penetration zone, which catalyses a series of additional inelastic energy dissipating mechanisms such as interfacial and intracrystalline nanocracking, viscoplastic stretching of interfacial organic material, and nanograin formation and reorientation.

Pervasive nanoscale deformation twinning as a catalyst for efficient energy dissipation in a bioceramic armour.

Calcium supplementation, particularly with vitamin D, has been an approved public health intervention to reduce fracture risk. Enthusiasm for this intervention has been mitigated by meta-analyses suggesting that calcium supplementation with or without vitamin D increases myocardial infarction (MI) risk; however, concern has been raised over the design of these meta-analyses. We, therefore, undertook a meta-analysis of randomized controlled trials with placebo or no-treatment control groups to determine if these supplements increase all-cause mortality and coronary heart disease (CHD) risk including MI, angina pectoris and acute coronary syndrome, and chronic CHD verified by clinical review, hospital record, or death certificate in elderly women. The Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE databases were searched from January 1, 1966, to May 24, 2013, for potentially eligible studies, reference lists were checked, and trial investigators were contacted where additional unpublished data were required. The search yielded 661 potentially eligible reports of which 18 met the inclusion criteria and contributed information on 63,563 participants with 3390 CHD events and 4157 deaths. Two authors extracted the data independently with trial data combined using random-effects meta-analysis to calculate the relative risk (RR). Five trials contributed CHD events with pooled relative RR of 1.02 (95% confidence interval [CI], 0.96-1.09; p = 0.51). Seventeen trials contributed all-cause mortality data with pooled RR of 0.96 (95% CI, 0.91-1.02; p = 0.18). Heterogeneity among the trials was low for both primary outcomes (I(2)  = 0%). For secondary outcomes, the RR for MI was 1.08 (95% CI, 0.92-1.26; p = 0.32), angina pectoris and acute coronary syndrome 1.09 (95% CI, 0.95-1.24; p = 0.22) and chronic CHD 0.92 (95% CI, 0.73-1.15; p = 0.46). In conclusion, current evidence does not support the hypothesis that calcium supplementation with or without vitamin D increases coronary heart disease or all-cause mortality risk in elderly women.

The effects of calcium supplementation on verified coronary heart disease hospitalization and death in postmenopausal women: a collaborative meta-analysis of randomized controlled trials.

The often astonishing material properties of crystalline biominerals are generally related to the hierarchical assembly of specifically interacting organic and inorganic components. To synthesize new materials with similar advanced properties applying nature's biomimeralization strategies we need to unravel the mechanisms of biologically and biomimetically controlled mineral formation. Since the literature is extensive this tutorial review is focussed on CaCO(3), the most abundant biomineral. We will first review the different approaches to biomimetic mineralization and describe the most recent advancements in the field. Subsequently the importance of in situ and time-resolved experiments, with their possibilities and limitations, is discussed with selected references.

In situ techniques in biomimetic mineralization studies of calcium carbonate.

Ultraviolet (UV) radiation induces adaptive responses that can be used for plant production improvement. The aim of this study was to assess the effect of solar UV exclusion on the physiology and phenolic compounds of leaves and berry skins of Vitis vinifera L. cv. Graciano under field conditions. Phenolic compounds were analyzed globally and individually in both the vacuolar fraction and, for the first time in grapevine, the cell wall-bound fraction. These different locations may represent diverse modalities of phenolic response to and protection against UV. UV exclusion led to a decrease in Fv /Fm in leaves, revealing that solar UV is needed for adequate photoprotection. Only p-caffeoyl-tartaric acid from the soluble fraction of leaves and myricetin-3-O-glucoside from the soluble fraction of berry skins were significantly higher in the presence of UV radiation, and thus they could play a role in UV protection. Other hydroxycinnamic acids, flavonols, flavanols and stilbenes did not respond to UV exclusion. UV exclusion led to subtle changes in leaves and berry skins of Graciano cultivar, which would be well adapted to current UV levels. This may help support decision-making on viticultural practices modifying UV exposure of leaves and berries, which could improve grape and wine quality.

Effects of UV exclusion on the physiology and phenolic composition of leaves and berries of Vitis vinifera cv. Graciano.

Carotenoids and tocopherols from botanical species abundant in Atlantic mountain grasslands were simultaneously extracted using one-step solid-liquid phase. A single n-hexane/2-propanol extract containing both types of compounds was injected twice under two different sets of HPLC conditions to separate the tocopherols by normal-phase chromatography and carotenoids by reverse-phase mode. The method allowed reproducible quantification in plant samples of very low amounts of α-, β-, γ- and δ-tocopherols (LOD from 0.0379 to 0.0720 μg g(-1) DM) and over 15 different xanthophylls and carotene isomers. The simplified one-step extraction without saponification significantly increased the recovery of tocopherols and carotenoids, thereby enabling the determination of α-tocopherol acetate in plant samples. The two different sets of chromatographic analysis provided near baseline separation of individual compounds without interference from other lipid compounds extracted from plants, and a very sensitive and accurate detection of tocopherols and carotenoids. The detection of minor individual components in botanical species from grasslands is nowadays of high interest in searching for biomarkers for foods derived from grazing animals.

Simultaneous analysis of carotenoids and tocopherols in botanical species using one step solid-liquid extraction followed by high performance liquid chromatography.

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