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Nature Reviews. Nephrology Sep 2016The most common presentation of nephrolithiasis is idiopathic calcium stones in patients without systemic disease. Most stones are primarily composed of calcium oxalate... (Review)
Review
The most common presentation of nephrolithiasis is idiopathic calcium stones in patients without systemic disease. Most stones are primarily composed of calcium oxalate and form on a base of interstitial apatite deposits, known as Randall's plaque. By contrast some stones are composed largely of calcium phosphate, as either hydroxyapatite or brushite (calcium monohydrogen phosphate), and are usually accompanied by deposits of calcium phosphate in the Bellini ducts. These deposits result in local tissue damage and might serve as a site of mineral overgrowth. Stone formation is driven by supersaturation of urine with calcium oxalate and brushite. The level of supersaturation is related to fluid intake as well as to the levels of urinary citrate and calcium. Risk of stone formation is increased when urine citrate excretion is <400 mg per day, and treatment with potassium citrate has been used to prevent stones. Urine calcium levels >200 mg per day also increase stone risk and often result in negative calcium balance. Reduced renal calcium reabsorption has a role in idiopathic hypercalciuria. Low sodium diets and thiazide-type diuretics lower urine calcium levels and potentially reduce the risk of stone recurrence and bone disease.
Topics: Apatites; Calcium; Humans; Hypercalciuria; Kidney Calculi
PubMed: 27452364
DOI: 10.1038/nrneph.2016.101 -
Joint Bone Spine Dec 2018Calcific tendonitis of the rotator cuff is due to apatite deposits in the shoulder tendons. Patients affected by calcific tendonitis have chronic shoulder pain and... (Review)
Review
Calcific tendonitis of the rotator cuff is due to apatite deposits in the shoulder tendons. Patients affected by calcific tendonitis have chronic shoulder pain and disability. Although the disease is frequent, about 10 to 42% of painful shoulders, mechanisms leading to this pathological mineralization are still largely unknown. Research reported in the 1990s suggested that the formation of calcific deposits is linked to cells looking like chondrocytes identified around calcium deposits within a fibrocartilage area. They were considered to be derived from tenocytes but more recently, tendon stem cells, able to differentiate into chondrocytes, were isolated. The pro-mineralizing properties of these chondrocytes-like cells, especially the role of alkaline phosphatase, are not currently clarified. The calcium deposits contain poorly crystalline carbonated apatite associated with protein. Among these proteins, only osteopontin has been consistently identified as a potential regulating factor. During the disease, spontaneous resorption can occur with migration of apatite crystals into the subacromial bursa causing severe pain and restriction of movement. In in vivo and in vitro experiments, apatite crystals were able to induce an influx of leucocytes and a release of IL-1β and IL-18 through the activation of the NLRP3 inflammasome. However, mechanisms leading to spontaneous resolution of this inflammation and disappearance of the calcification still need to be elucidated.
Topics: Apatites; Calcinosis; Humans; Rotator Cuff; Shoulder Joint; Tendinopathy; Tendons
PubMed: 29195923
DOI: 10.1016/j.jbspin.2017.10.004 -
International Journal of Molecular... Nov 2022The aim of the study was to analyze the chemical−physical properties and bioactivity (apatite-forming ability) of three recently introduced premixed bioceramic root...
The aim of the study was to analyze the chemical−physical properties and bioactivity (apatite-forming ability) of three recently introduced premixed bioceramic root canal sealers containing varied amounts of different calcium silicates (CaSi): a dicalcium and tricalcium silicate (1−10% and 20−30%)-containing sealer with zirconium dioxide and tricalcium aluminate (CERASEAL); a tricalcium silicate (5−15%)-containing sealer with zirconium dioxide, dimethyl sulfoxide and lithium carbonate (AH PLUS BIOCERAMIC) and a dicalcium and tricalcium silicate (10% and 25%)-containing sealer with calcium aluminate, tricalcium aluminate and tantalite (NEOSEALER FLO). An epoxy resin-based sealer (AH PLUS) was used as control. The initial and final setting times, radiopacity, flowability, film thickness, open pore volume, water absorption, solubility, calcium release and alkalizing activity were tested. The nucleation of calcium phosphates and/or apatite after 28 days aging in Hanks balanced salt solution (HBSS) was evaluated by ESEM-EDX, vibrational IR and micro-Raman spectroscopy. The analyses showed for NeoSealer Flo and AH Plus the longest final setting times (1344 ± 60 and 1300 ± 60 min, respectively), while shorter times for AH Plus Bioceramic and Ceraseal (660 ± 60 and 720 ± 60 min, respectively). Radiopacity, flowability and film thickness complied with ISO 6876/12 for all tested materials. A significantly higher open pore volume was observed for NeoSealer Flo, AH Plus Bioceramic and Ceraseal when compared to AH Plus (p < 0.05), significantly higher values were observed for NeoSealer Flo and AH Plus Bioceramic (p < 0.05). Ceraseal and AH Plus revealed the lowest solubility. All CaSi-containing sealers released calcium and alkalized the soaking water. After 28 days immersion in HBSS, ESEM-EDX analyses revealed the formation of a mineral layer that covered the surface of all bioceramic sealers, with a lower detection of radiopacifiers (Zirconium for Ceraseal and AH Plus Bioceramic, Tantalum for NeoSealer Flo) and an increase in calcium, phosphorous and carbon. The calcium phosphate (CaP) layer was more evident on NeoSealer Flo and AH Plus Bioceramic. IR and micro-Raman revealed the formation of calcium carbonate on the surface of all set materials. A thin layer of a CaP phase was detected only on AH Plus Bioceramic and NeoSealer Flo. Ceraseal did not show CaP deposit despite its highest calcium release among all the tested CaSi-containing sealers. In conclusion, CaSi-containing sealers met the required chemical and physical standards and released biologically relevant ions. Slight/limited apatite nucleation was observed in relation to the high carbonation processes.
Topics: Root Canal Filling Materials; Calcium; Dental Pulp Cavity; Silicates; Water; Apatites
PubMed: 36430393
DOI: 10.3390/ijms232213914 -
International Journal of Molecular... Aug 2022Apatites are one of the most intensively studied materials for possible biomedical applications. New perspectives of possible application of apatites correspond with the...
Apatites are one of the most intensively studied materials for possible biomedical applications. New perspectives of possible application of apatites correspond with the development of nanomaterials and nanocompounds. Here, an effort to systematize different kinds of human bioapatites forming bones, dentin, and enamel was undertaken. The precursors of bioapatites and hydroxyapatite were also considered. The rigorous consideration of compositions and stoichiometry of bioapatites allowed us to establish an order in their mutual sequence. The chemical reactions describing potential transformations of biomaterials from octacalcium phosphate into hydroxyapatite via all intermediate stages were postulated. Regardless of whether the reactions occur in reality, all apatite biomaterials behave as if they participate in them. To conserve the charge, additional free charges were introduced, with an assumed meaning to be joined with the defects. The distribution of defects was coupled with the values of crystallographic parameters "" and "". The energetic balances of bioapatite transformations were calculated. The apatite biomaterials are surprisingly regular structures with non-integer stoichiometric coefficients. The results presented here will be helpful for the further design and development of nanomaterials.
Topics: Apatites; Biocompatible Materials; Bone and Bones; Crystallography; Durapatite; Humans
PubMed: 36076932
DOI: 10.3390/ijms23179537 -
Journal of Dental Research Jun 2015Enamel is unique. It is the only epithelial-derived mineralized tissue in mammals and has a distinct micro- and nanostructure with nanofibrous apatite crystals as... (Review)
Review
Enamel is unique. It is the only epithelial-derived mineralized tissue in mammals and has a distinct micro- and nanostructure with nanofibrous apatite crystals as building blocks. It is synthesized by a highly specialized cell, the ameloblast, which secretes matrix proteins with little homology to any other known amino acid sequence, but which is composed of a primary structure that makes it competent to self-assemble and control apatite crystal growth at the nanometer scale. The end-product of ameloblast activity is a marvel of structural engineering: a material optimized to provide the tooth with maximum biting force, withstanding millions of cycles of loads without catastrophic failure, while also protecting the dental pulp from bacterial attack. This review attempts to bring into context the mechanical behavior of enamel with the developmental process of amelogenesis and structural development, since they are linked to tissue function, and the importance of controlling calcium phosphate mineralization at the nanometer scale. The origins of apatite nanofibers, the development of a stiffness gradient, and the biological processes responsible for the synthesis of a hard and fracture-resistant dental tissue are discussed with reference to the evolution of enamel from a fibrous composite to a complex, tough, and damage-tolerant coating on dentin.
Topics: Ameloblasts; Amelogenesis; Apatites; Biomechanical Phenomena; Calcium Phosphates; Crystallization; Dental Enamel; Dental Enamel Proteins; Humans; Nanofibers; Tooth Calcification
PubMed: 25800708
DOI: 10.1177/0022034515577963 -
Dental Materials : Official Publication... Nov 2022The aim of this study was to investigate the degradation of inert glass fillers which are commonly used in conventional resin-based composites to provide radiopacity,...
OBJECTIVES
The aim of this study was to investigate the degradation of inert glass fillers which are commonly used in conventional resin-based composites to provide radiopacity, reduce the polymerization shrinkage and improve the mechanical properties.
METHODS
75 mg of five different glass powders (1 µm) was immersed separately into 50 mL of acetic acid (pH 4) and tris buffer (pH 7.4) for up to 4 weeks. At each time point the glass powder was filtered and dried for characterization using ATR-FTIR and XRD to assess the degradation behavior and crystallization. ICP-OES, ISE and pH measurements were performed on the supernatant solutions to monitor the pH and ion release.
RESULTS
Although FTIR and XRD analysis showed no significant glass degradation or crystallization upon immersion, there was a substantial release of ions from the inert fillers, especially from BABFG and CDL. Barium release for these fillers were 270 and 165 ppm respectively. G018-373 glass presented the lowest ion release followed by GM27884 and BABG. The ion release was more pronounced in acidic conditions compared to neutral conditions apart from the fluoride release.
SIGNIFICANCE
Inert glasses are not as inert as previously thought. This may result in leaching of ions, potentially causing toxicity, reduction in mechanical properties, increased wear and subsequent failure of the composite material. The ions released from the inert glass may interfere with other glass fillers such as bioactive glass fillers, inhibiting degradation of the bioactive glass, beneficial ion release from the bioactive glass, pH neutralization and apatite formation.
Topics: Apatites; Barium; Fluorides; Glass; Materials Testing; Powders; Tromethamine
PubMed: 36154969
DOI: 10.1016/j.dental.2022.09.004 -
Journal of Structural Biology Dec 2021During enamel formation, the organic enamel protein matrix interacts with calcium phosphate minerals to form elongated, parallel, and bundled enamel apatite crystals of... (Review)
Review
During enamel formation, the organic enamel protein matrix interacts with calcium phosphate minerals to form elongated, parallel, and bundled enamel apatite crystals of extraordinary hardness and biomechanical resilience. The enamel protein matrix consists of unique enamel proteins such as amelogenin, ameloblastin, and enamelin, which are secreted by highly specialized cells called ameloblasts. The ameloblasts also facilitate calcium and phosphate ion transport toward the enamel layer. Within ameloblasts, enamel proteins are transported as a polygonal matrix with 5 nm subunits in secretory vesicles. Upon expulsion from the ameloblasts, the enamel protein matrix is re-organized into 20 nm subunit compartments. Enamel matrix subunit compartment assembly and expansion coincide with C-terminal cleavage by the MMP20 enamel protease and N-terminal amelogenin self-assembly. Upon enamel crystal precipitation, the enamel protein phase is reconfigured to surround the elongating enamel crystals and facilitate their elongation in C-axis direction. At this stage of development, and upon further amelogenin cleavage, central and polyproline-rich fragments of the amelogenin molecule associate with the growing mineral crystals through a process termed "shedding", while hexagonal apatite crystals fuse in longitudinal direction. Enamel protein sheath-coated enamel "dahlite" crystals continue to elongate until a dense bundle of parallel apatite crystals is formed, while the enamel matrix is continuously degraded by proteolytic enzymes. Together, these insights portrait enamel mineral nucleation and growth as a complex and dynamic set of interactions between enamel proteins and mineral ions that facilitate regularly seeded apatite growth and parallel enamel crystal elongation.
Topics: Ameloblasts; Amelogenesis; Amelogenin; Animals; Apatites; Calcium; Calcium Phosphates; Crystallization; Dental Enamel; Dental Enamel Proteins; Humans; Microscopy, Electron; Minerals
PubMed: 34748943
DOI: 10.1016/j.jsb.2021.107809 -
BioMed Research International 2013Calcium phosphate apatites are inorganic compounds encountered in many different mineralized tissues. Bone mineral, for example, is constituted of nanocrystalline... (Review)
Review
Calcium phosphate apatites are inorganic compounds encountered in many different mineralized tissues. Bone mineral, for example, is constituted of nanocrystalline nonstoichiometric apatite, and the production of "analogs" through a variety of methods is frequently reported. In another context, the ability of solid surfaces to favor the nucleation and growth of "bone-like" apatite upon immersion in supersaturated fluids such as SFB is commonly used as one evaluation index of the "bioactivity" of such surfaces. Yet, the compounds or deposits obtained are not always thoroughly characterized, and their apatitic nature is sometimes not firmly assessed by appropriate physicochemical analyses. Of particular importance are the "actual" conditions in which the precipitation takes place. The precipitation of a white solid does not automatically indicate the formation of a "bone-like carbonate apatite layer" as is sometimes too hastily concluded: "all that glitters is not gold." The identification of an apatite phase should be carefully demonstrated by appropriate characterization, preferably using complementary techniques. This review considers the fundamentals of calcium phosphate apatite characterization discussing several techniques: electron microscopy/EDX, XRD, FTIR/Raman spectroscopies, chemical analyses, and solid state NMR. It also underlines frequent problems that should be kept in mind when making "bone-like apatites."
Topics: Apatites; Biomimetic Materials; Crystallization; Microscopy, Electron, Scanning; Spectrometry, X-Ray Emission; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction
PubMed: 23984373
DOI: 10.1155/2013/490946 -
Calcified Tissue International Oct 2013Relationships between geological phosphorite deposition and biological apatite nucleation have often been overlooked. However, similarities in biological apatite and... (Review)
Review
Relationships between geological phosphorite deposition and biological apatite nucleation have often been overlooked. However, similarities in biological apatite and phosphorite mineralogy suggest that their chemical formation mechanisms may be similar. This review serves to draw parallels between two newly described phosphorite mineralization processes, and proposes a similar novel mechanism for biologically controlled apatite mineral nucleation. This mechanism integrates polyphosphate biochemistry with crystal nucleation theory. Recently, the roles of polyphosphates in the nucleation of marine phosphorites were discovered. Marine bacteria and diatoms have been shown to store and concentrate inorganic phosphate (Pi) as amorphous, polyphosphate granules. Subsequent release of these P reserves into the local marine environment as Pi results in biologically induced phosphorite nucleation. Pi storage and release through an intracellular polyphosphate intermediate may also occur in mineralizing oral bacteria. Polyphosphates may be associated with biologically controlled apatite nucleation within vertebrates and invertebrates. Historically, biological apatite nucleation has been attributed to either a biochemical increase in local Pi concentration or matrix-mediated apatite nucleation control. This review proposes a mechanism that integrates both theories. Intracellular and extracellular amorphous granules, rich in both calcium and phosphorus, have been observed in apatite-biomineralizing vertebrates, protists, and atremate brachiopods. These granules may represent stores of calcium-polyphosphate. Not unlike phosphorite nucleation by bacteria and diatoms, polyphosphate depolymerization to Pi would be controlled by phosphatase activity. Enzymatic polyphosphate depolymerization would increase apatite saturation to the level required for mineral nucleation, while matrix proteins would simultaneously control the progression of new biological apatite formation.
Topics: Animals; Apatites; Bacteria; Calcification, Physiologic; Calcium; Diatoms; Geology; Humans; Invertebrates; Microscopy, Fluorescence; Minerals; Mitochondria; Phosphates; Phosphorus; Polyphosphates; Spectrometry, Fluorescence; Vertebrates
PubMed: 24077874
DOI: 10.1007/s00223-013-9784-9 -
The American Journal of Medicine Nov 1987Calcium pyrophosphate and apatite crystals are common in osteoarthritic knee effusions. One or the other crystal was found in 60 percent or more of cases. These crystals... (Review)
Review
Calcium pyrophosphate and apatite crystals are common in osteoarthritic knee effusions. One or the other crystal was found in 60 percent or more of cases. These crystals offer the potential for mechanical effects in cartilage but are also often phagocytized by synovial cells. A low-grade inflammation with release of proteases and other mediators of inflammation may be an important factor in the pain and joint damage of osteoarthritis. Crystal-associated changes may merit specific attention in any future approach to therapy.
Topics: Apatites; Calcium Pyrophosphate; Crystallization; Diphosphates; Humans; Inflammation; Knee Joint; Microscopy, Electron; Osteoarthritis; Phagocytosis; Synovial Fluid; Synovial Membrane
PubMed: 2825522
DOI: 10.1016/0002-9343(87)90845-x