Calcium Crystals Research Articles

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

Crystals of calcium oxalate often form in cells adjacent to the vascular bundles in the tissues along the xylem stream. This spatial crystal pattern suggests a role for calcium oxalate formation in regulating calcium transport and partitioning to edible organs such as seeds. To investigate this potential role, microscopic and biochemical comparisons were conducted on the different tissues of Medicago truncatula wild-type and the calcium oxalate defective (cod) 5 which lacks the ability to accumulate prismatic crystals in the cells adjacent to the vascular bundles. Calcium measurements showed that cod5 seeds had more calcium and cod5 pods contained less calcium than the corresponding wild-type tissues. Roots, stems, and leaves from cod5 and wild-type had similar calcium content. Although cod5 was devoid of prismatic crystals, cod5 pods were observed to form druse crystals of calcium oxalate not found in wild-type pods. Taken together these findings suggest a functional role for calcium oxalate formation in regulating calcium transport to the seeds. Regulating calcium uptake at the roots also appeared to be another point of control in determining seed calcium content. Overall, regulating the long distance transport and partitioning of calcium to the seeds appears to be a complex process with multiple points of control.

Матриксний Gla-протеїн та його роль у кальцифікації судинної стінки

Data on the structure of matrix Gla-protein (MGP), its chemical characteristics, regulation of synthesis and post-translational modifications are described. The information on the structure of the MGP gene, its well distributed polymorphisms are presented. Factors that regulate expression and activity of MGP include vitamin D, retinoic acid, extracellular calcium ions, cytokines, and some hormones. It is emphasized that MGP is an important inhibitor of calcification of soft tissues. These properties of this protein are associated with the presence of residues of gamma-carboxiglutamic acid of its molecule. Four possible mechanisms of anticalcinogenic action of MGP are described: binding with calcium ions and crystals of hydroxyapatite, binding to extracellular matrix components, interaction with bone morphogenetic protein (BMP-2) and elimination the effects of the latter, participation in the regulation of apoptosis. It is emphasized that the study of allelic variants of the MGP gene is important in the context of their possible association with the development of cardiovascular and other diseases.

Phylogeny of whey acidic protein (WAP) four-disulfide core proteins and their role in lower vertebrates and invertebrates

Proteins containing WAP (whey acidic protein) domains with a characteristic WFDC (WAP four-disulfide core) occur not only in mammals (including marsupials and monotremes) but also in birds, reptiles, amphibians and fish. In addition, they are present in numerous invertebrates, from cnidarians to urochordates. Many of those from non-mammalian groups are poorly understood with respect to function or phylogeny. Those well characterized so far are waprins from snakes, perlwapins from bivalves and crustins from decapod crustaceans. Waprins are venom proteins with a single WAP domain at the C-terminus. They display antimicrobial, rather than proteinase inhibitory, activities. Perlwapins, in contrast, possess three WAP domains at the C-terminus and are expressed in the shell nacre of abalones. They participate in shell formation by inhibiting the growth of calcium crystals in the shell. The crustin group is the largest of all WFDC-containing proteins in invertebrates with the vast majority being highly expressed in the haemocytes. Most have a single WAP domain at the C-terminus. The presence and type of the domains between the signal sequence and the C-terminus WAP domain separate the different crustin types. Most of the TypeI and II crustins are antimicrobial towards Gram-positive bacteria, whereas the TypeIII crustins tend to display protease inhibition. Expression studies show that at least some crustins have other important biological effects, as levels change with physiological stress, wound repair, tissue regeneration or ecdysis. Thus WAP domains are widely distributed and highly conserved, serving in diverse physiological processes (proteinase inhibition, bacterial killing or inhibition of calcium transport).

Crucial role of the cryptic epitope SLAYGLR within osteopontin in renal crystal formation of mice

Osteopontin plays a crucial role in the formation of renal calcium crystals, which are primarily induced by renal tubular cell injury, especially mitochondrial damage. We have previously shown that the impaired Arg-Gly-Asp (RGD) sequence of osteopontin inhibits renal crystal formation by using OPN-transgenic mice and OPN-knockout (OPN-KO) mice. Here, we investigated the effects of an antimurine osteopontin antibody (35B6-Ab) that specifically reacts with the (162) SLAYGLR(168) sequence, which is exposed by thrombin cleavage and is located adjacent to the RGD sequence, on renal crystal formation. Renal crystals induced by daily administration of glyoxylate over 9 days (from days 1 to 9) in a murine model were sporadically detected in the renal tubular cells at the corticomedullary junction, where thrombin-cleaved osteopontin expression was also coincidentally detected. On days 0, 3, 6, and 9, 35B6-Ab administration inhibited renal crystal formation and induced significant morphological changes in a dose-dependent manner (250, 500, and 1000 µg per mouse). Scanning electron microscopy showed that the crystals in 35B6-Ab-treated mice were aberrantly formed and their density was low; in contrast, the crystals in untreated mice that were not administered 35B6-Ab had a radial pattern of growth (rosette petal-like crystals), and their density was high. Microstructure analysis of renal tubular cells by transmission electron microscopy revealed that untreated mice showed collapsed mitochondria in the flattened cytoplasm of renal tubular cells, unlike the corresponding structures in 35B6-Ab-treated mice, in which renal tubular cell injury was inhibited. In vitro, 35B6-Ab was found to inhibit the attachment of (14) C-labeled crystals to renal tubular culture cells and reduce morphological damage to these cells. We conclude that thrombin-cleaved osteopontin plays an important role in formation of renal calcium crystals and that 35B6-Ab contributes to the remarkable inhibition of early-stage renal crystal formation by preventing renal tubular cell injury and crystal-cell attachment.

NLRP3 inflammasome plays a critical role in the pathogenesis of hydroxyapatite-associated arthropathy

The proinflammatory and catabolic cytokine IL-1β has been implicated in the pathogenesis of osteoarthritis (OA) by mediating synovial inflammation and cartilage degeneration. Although synovial macrophages are suggested to be the source of IL-1β, the mechanism remains unclear. Ectopic deposition of hydroxyapatite (HA) crystals in joints is closely associated with OA and other arthropathies, but the precise role of HA in arthritis pathogenesis has not been clearly demonstrated. Here we show that HA crystals of a particular size and shape can stimulate robust secretion of proinflammatory cytokines IL-1β and IL-18 from murine macrophages in a NLRP3 inflammasome-dependent manner. HA-induced inflammasome activation is dependent on potassium efflux, generation of reactive oxygen species (ROS), and lysosomal damage, but independent of cell death. Mice lacking the inflammasome components are protected against HA-induced neutrophilic inflammation in the air-pouch model of synovitis, and they show decreased joint pathology accompanying spontaneous HA deposition in the ank-deficient mouse model of arthritis. Moreover, calcium crystal positive synovial fluids from some OA patients exhibited inflammasome-stimulatory activity in vitro. These results demonstrate that the NLRP3 inflammasome mediates the pathological effect of HA crystals in vitro and in vivo and suggest a critical role for the inflammasome in the pathogenesis of OA.

Matrix vesicles are present in human osteoarthritic synovial fluid and promote formation of monosodium urate crystals

BackgroundMatrix vesicles (MVs) are membrane-bound organelles that are physiologic components of the extracellular matrix of connective tissues. MVs from articular cartilage are well characterised and range in size from 50–100...

First-principles calculation of the energy of compressed calcium

The energy of a calcium crystal with a simple cubic lattice as a function of the ratio (t/U) between two internal parameters of the Hubbard model has been calculated using the Hubbard model for the s bands, equations of motion, and direct algebraic method. The electronic spectra have been calculated for the 4s band of the crystal in two principal symmetry directions of the first Brillouin zone. The calculations have been performed at temperatures T1 = 0 K and T2 = 1000 K. All calculations have been carried out for different interaction energies U of s electrons, one angle, and their different concentrations n in the range 0 ≤ n ≤ 2. The calculations have demonstrated that the dependences of the energy and electronic spectra in this compressed state are very smooth. The occupation of the Ca 4s band is in good agreement with the results of the pioneering calculations of compressed Ca (and a number of other metals), which were carried out by Gandel’man and his colleagues in the Wigner-Seitz spherical cell approximation. It has been shown that the performed analysis accurately reproduces the data obtained on the superconductivity in terms of the Bardeen-Cooper-Schrieffer theory if the 4s band is half-occupied.

Loss of NPP1 induces cartilage remodelling into bone and OA-like changes in mice

BackgroundCartilage calcification is common in osteoarthritis (OA) and correlates with the severity of cartilage breakdown. Nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) contributes to maintain an optimal balance of pyrophosphate (PPi) and...

Proteomic analysis of articular cartilage vesicles from normal and osteoarthritic cartilage

Articular cartilage vesicles (ACVs) are extracellular organelles found in normal articular cartilage. While they were initially defined by their ability to generate pathologic calcium crystals in cartilage of osteoarthritis (OA) patients, they can also alter the phenotype of normal chondrocytes through the transfer of RNA and protein. The purpose of this study was to analyze the proteome of ACVs from normal and OA human cartilage. ACVs were isolated from cartilage samples from 10 normal controls and 10 OA patients. We identified the ACV proteomes using in-gel trypsin digestion, nanospray liquid chromatography tandem mass spectrometry analysis of tryptic peptides, followed by searching an appropriate subset of the Uniprot database. We further differentiated between normal and OA ACVs by Holm-Sidak analysis for multiple comparison testing. More than 1,700 proteins were identified in ACVs. Approximately 170 proteins satisfied our stringent criteria of having >1 representative peptide per protein present, and a false discovery rate of ≤5%. These proteins included extracellular matrix components, phospholipid binding proteins, enzymes, and cytoskeletal components, including actin. While few proteins were seen exclusively in normal or OA ACVs, immunoglobulins and complement components were present only in OA ACVs. Compared to normal ACVs, OA ACVs displayed decreases in matrix proteoglycans and increases in transforming growth factor β-induced protein βig-H3, DEL-1, vitronectin, and serine protease HtrA1 (P < 0.01). These findings lend support to the concept of ACVs as physiologic structures in articular cartilage. Changes in OA ACVs are largely quantitative and reflect an altered matrix and the presence of inflammation, rather than revealing fundamental changes in composition.

Detection of basic calcium phosphate crystals in osteoarthritis

Osteoarthritis (OA) is the most common human joint disorder. Its complex pathogenesis remains poorly understood but appears multifactorial. To date, no specific pharmacological agent has been identified to alter the disease course of OA. Calcification of articular cartilage is a hallmark of OA and evidence suggests it contributes directly to joint degeneration. Calcium crystals are frequently found in OA synovial fluid but their exact role in the disease process is unclear. Basic calcium phosphate (BCP) crystals are the predominant crystal type found in OA and recent data indicate a pathogenic role for these crystals in OA. However, information on the exact frequency and distribution of BCP crystals vary considerably, mainly due to the lack of simple and reliable methods of detection. The purpose of this review is to describe the current available methods for detecting BCP crystals and to highlight their obvious advantages and limitations. Recent developments in the field are also discussed with particular reference to their potential clinical applicability. Improved methods of detection for BCP crystals could potentially aid the diagnosis of OA and the development of novel therapies.

Lymphatic vasculature is increased in heart valves, ischaemic and inflamed hearts and in cholesterol-rich and calcified atherosclerotic lesions

Despite the importance of myocardial vasculature in many pathological conditions, little information is available about cardiac and coronary lymphatic vessels in normal and pathological conditions. Vasculature was assessed by immunohistochemistry with CD 31 and lymphatic endothelium with markers podoplanin and LYVE-1 in 16 children and 20 adult autopsy hearts. Valve biopsies were collected from eight adults. The highest number of lymphatics was found in valves in infective endocarditis, where they accounted nearly 100% of all vessels in certain areas. An increased number of lymphatics was also found in degenerative calcified stenosis, whereas the number was reduced in myxoid degeneration. Lymphatics grew in areas rich in extracellular matrix, whereas inflammatory cell-rich areas were more prone to angiogenesis. Progressive atherosclerotic lesions rich in calcium and cholesterol crystals revealed increased lymphangiogenesis in media. The highest number of myocardial lymphatics was found in epicardium of ischaemic hearts in both acute and chronic phase. Additionally, an increased number of lymphatics accompanied myocarditis and acute myocardial infarction. The highest number of lymphatics was found in valves in infective endocarditis. Increases in lymphatics also accompanied major cardiac pathological changes, such as acute and chronic ischaemia, progressive atherosclerosis, myocarditis and hypertrophy. Thus, blocking of excess lymphangiogenesis might be useful in progressive atherosclerosis, whereas stimulation of lymphatic vascular growth and function might be useful in cardiac hypertrophy and heart failure.

Renal Calcification in NICU Patients

Sequential renal ultrasonographic studies have shown renal calcifications to be more common in neonatal intensive care unit (NICU) patients than is commonly believed, especially in extremely low-birthweight (ELBW) infants. A family history of kidney stones is an independent risk factor for renal calcifications in ELBW infants. Understanding the role of inhibitors and promoters in crystal formation helps in understanding the pathophysiology of nephrocalcinosis. Identification of the presence or absence of hypercalcemia and hypercalciuria is an effective method of directing the diagnostic evaluation of infants who have nephrocalcinosis. Fortunately, ultrasonographic renal calcifications resolve spontaneously in most NICU patients. Renal calcifications can be associated with persistent abnormalities in renal function if hypercalciuria continues, such as in the rare very low-birthweight (VLBW) infant who receives long-term furosemide therapy after hospital discharge. Only in rare cases, often inborn errors of metabolism, can renal calcifications in NICU patients progress to chronic renal injury, such as in infants who have primary hyperoxaluria that involves persistence of oxalate in the urine, a potent promoter of calcium crystal formation.

Effects of Orthosiphon grandiflorus, Hibiscus sabdariffa and Phyllanthus amarus Extracts on Risk Factors for Urinary Calcium Oxalate Stones in Rats

We evaluated the antilithic effect of Orthosiphon grandiflorus, Hibiscus sabdariffa and Phyllanthus amarus extracts on known risk factors for calcium oxalate stones in rats. We divided 30 male Wistar rats into 5 equal groups. Controls were fed a standard diet and the remaining groups received a 3% glycolate diet for 4 weeks to induce hyperoxaluria. One glycolate fed group served as the untreated group and the others were given oral extracts of Orthosiphon grandiflorus, Hibiscus sabdariffa or Phyllanthus amarus at a dose of 3.5 mg daily. We collected 24-hour urine and blood samples. Kidneys were harvested for histological examination. We measured the renal tissue content of calcium and oxalate. The Hibiscus sabdariffa group showed significantly decreased serum oxalate and glycolate, and higher oxalate urinary excretion. The Phyllanthus amarus group showed significantly increased urinary citrate vs the untreated group. Histological examination revealed less CaOx crystal deposition in the kidneys of Hibiscus sabdariffa and Phyllanthus amarus treated rats than in untreated rats. Those rats also had significantly lower renal tissue calcium content than untreated rats. All parameters in the Orthosiphon grandiflorus treated group were comparable to those in the untreated group. Hibiscus sabdariffa and Phyllanthus amarus decreased calcium crystal deposition in the kidneys. The antilithic effect of Hibiscus sabdariffa may be related to decreased oxalate retention in the kidney and more excretion into urine while that of Phyllanthus amarus may depend on increased urinary citrate. In contrast, administering Orthosiphon grandiflorus had no antilithic effect.

Field Application of Calcium to Reduce Phytophthora Stem Rot of Soybean, and Calcium Distribution in Plants.

The effect of calcium compounds [Ca(HCOO)2-A and Ca(NO3)2] on the incidence of Phytophthora stem rot of soybean (Glycine max) cv. Tanbakuro was investigated in the field. Disease incidence in control plants in three fields naturally infested with Phytophthora sojae ranged from 11.7 to 52.0% at 140 days after transplanting. Independent of the pathotype diversity, 4 and 10 mM of the calcium compounds applied twice (prior to transplanting and 14 days after transplanting) significantly suppressed disease incidence and delayed onset. Ca(HCOO)2-A (Suicaru) was more effective than calcium nitrate for reducing disease incidence. In most cases, the calcium amendments increased plant height, number of nodes and pods, and seed yields, and reduced low-quality seeds. Scanning electron microscopy with fresh samples showed increased accumulation of calcium crystals around the cambium and xylem elements of soybean plants treated with 10-mM Ca(HCOO)2-A and Ca(NO3)2. Mycelial penetration was inhibited at these sites. These results indicated that calcium-rich areas may be more resistant to invasion by P. sojae, and the calcium crystals may play an important role in calcium ion storage and its availability for those tissues to maintain long-term field resistance.

Dual-Energy Multidetector CT: How Does It Work, What Can It Tell Us, and When Can We Use It in Abdominopelvic Imaging?

Dual-energy CT provides information about how substances behave at different energies, the ability to generate virtual unenhanced datasets, and improved detection of iodine-containing substances on low-energy images. Knowing how a substance behaves at two different energies can provide information about tissue composition beyond that obtainable with single-energy techniques. The term K edge refers to the spike in attenuation that occurs at energy levels just greater than that of the K-shell binding because of the increased photoelectric absorption at these energy levels. K-edge values vary for each element, and they increase as the atomic number increases. The energy dependence of the photoelectric effect and the variability of K edges form the basis of dual-energy techniques, which may be used to detect substances such as iodine, calcium, and uric acid crystals. The closer the energy level used in imaging is to the K edge of a substance such as iodine, the more the substance attenuates. In the abdomen and pelvis, dual-energy CT may be used in the liver to increase conspicuity of hypervascular lesions; in the kidneys, to distinguish hyperattenuating cysts from enhancing renal masses and to characterize renal stone composition; in the adrenal glands, to characterize adrenal nodules; and in the pancreas, to differentiate between normal and abnormal parenchyma.

Calcium deposition in osteoarthritic meniscus and meniscal cell culture

IntroductionCalcium crystals exist in the knee joint fluid of up to 65% of osteoarthritis (OA) patients and the presence of these calcium crystals correlates with the radiographic evidence of hyaline cartilaginous degeneration. This study sought to examine calcium deposition in OA meniscus and to investigate OA meniscal cell-mediated calcium deposition. The hypothesis was that OA meniscal cells may play a role in pathological meniscal calcification.MethodsStudies were approved by our human subjects Institutional Review Board. Menisci were collected during joint replacement surgeries for OA patients and during limb amputation surgeries for osteosarcoma patients. Calcium deposits in menisci were examined by alizarin red staining. Expression of genes involved in biomineralization in OA meniscal cells was examined by microarray and real-time RT-PCR. Cell-mediated calcium deposition in monolayer culture of meniscal cells was examined using an ATP-induced 45calcium deposition assay.ResultsCalcium depositions were detected in OA menisci but not in normal menisci. The expression of several genes involved in biomineralization including ENPP1 and ANKH was upregulated in OA meniscal cells. Consistently, ATP-induced calcium deposition in the monolayer culture of OA meniscal cells was much higher than that in the monolayer culture of control meniscal cells.ConclusionsCalcium deposition is common in OA menisci. OA meniscal cells calcify more readily than normal meniscal cells. Pathological meniscal calcification, which may alter the biomechanical properties of the knee meniscus, is potentially an important contributory factor to OA.

The meniscus, calcification and osteoarthritis: a pathologic team

Articular calcification correlates with osteoarthritis (OA) severity but its exact role in the disease process is unclear. In examining OA meniscal cell function, Sun and colleagues have shown recently that meniscal cells from end-stage OA subjects can generate calcium crystals and that genes involved in calcification are upregulated in OA meniscal cells. Also, this in vitro calcium deposition by OA menisci is inhibited by phosphocitrate. This study should catalyse further work examining the pathological contribution or otherwise of calcium crystals in OA. This would significantly aid the development of potential disease modifying agents in OA, which are currently unavailable.

Resistance to Brown Ring Disease in the Manila clam, Ruditapes philippinarum: A study of selected stocks showing a recovery process by shell repair

European stocks of the Manila clam Ruditapes philippinarum are affected by the Brown Ring Disease (BRD), which is caused by Vibrio tapetis. BRD is characterized by an accumulation of a brown organic matrix on the inner face of the shell. Clams that recover from BRD develop a white mineralized layer covering the brown matrix. Stocks of clams that showed resistance to BRD development, as enhanced recovery, have been monitored since 2000. We have examined two selected stocks: a Low Susceptibility (LS) stock and a High Susceptibility stock (HS), over three generations. The LS stock showed less evidence of the BRD symptoms, and more evidence of total shell repair, both in the field and following experimental challenge with V. tapetis, indicating that some clams may be less vulnerable to a V. tapetis attack than others. The inner face of the valves of the LS and HS clams of the two last generations were analysed with scanning electron microscopy. Examination of shells from BRD-affected clams showed that during the repair process, calcium crystals were progressively laid down until the affected zone was entirely covered. By the end of the shell repair process, a final organic layer covered the calcium crystal mounds. This layer seemed essential in the recovery process. The results indicate that the shell repair capability of the clams is the principal mechanism implicated in the development of BRD resistance in the Manila clam stocks. However, this resistance did not increase with generation because the broodstock was maintained at a site where selection pressure was low, due to a low prevalence of V. tapetis.

Diagnosing Early or Rheumatoid Arthritis. Which Is Better: Expert Opinion or Evidence?

All clinicians know about the complexity in diagnosing rheumatoid arthritis (RA), especially early in the disease. Because RA lacks pathognomonic features — that is, there are no clinical, biological, or radiological characteristics specific to RA diagnosis — doubt about the diagnosis may persist for some patients1,2. Examples are patients with “nude” polyarthritis [i.e., without positivity for serum rheumatoid factor (RF), anti-citrullinated peptide antibodies, typical erosion, or all 3], or even elderly people with erosive RF-positive polyarthritis associated with psoriasis or calcium crystal deposition disease features seen on joint radiography. When RA is neither obvious nor completely excluded, the clinician strikes a balance between possible or probable RA, depending on the level of confidence. In this context, in clinical research, RA classification criteria may be of some help because they ensure, at the group level, the diagnosis of RA with minimal error. However, in clinical practice, RA criteria cannot be used as the gold standard, especially in early arthritis (EA), as was previously shown3–5. In this issue of The Journal, Morvan, et al report on a cohort of patients with EA followed for 10 years to investigate discrepancies in RA diagnosed by American College of Rheumatology (ACR) classification criteria and final diagnosis by an office-based rheumatologist6. The authors noted poor agreement at the onset of the disease, as has been shown, but also at 2 years, when ACR criteria are supposed to be more accurate. If one assumes that the rheumatologist is an expert, who is right: the expert or the criteria? Eminence … Address correspondence to Dr. B. Fautrel, Department of Rheumatology, Pitié-Salpêtrière Hospital, 83 boulevard de l’Hôpital, 75651 Paris cedex 13, France. E-mail: bruno.fautrel{at}psl.aphp.fr

Crystalline bacterial biofilm formation on urinary catheters by urease-producing urinary tract pathogens: a simple method of control

The problem of catheter encrustation stems from infection by urease-producing bacteria. These organisms generate ammonia from urea, elevate the pH of urine and cause crystals of calcium and magnesium phosphates to form in the urine and the biofilm that develops on the catheter. In this study, a laboratory model was used to compare the ability of 12 urease-positive species of urinary tract pathogens to encrust and block catheters. Proteus mirabilis, Proteus vulgaris and Providencia rettgeri were able to raise the urinary pH above 8.3 and produce catheter-blocking crystalline biofilms within 40 h. Morganella morganii and Staphylococcus aureus elevated the pH of urine to 7.4 and 6.9, respectively, and caused some crystal deposition in the biofilms but did not block catheters in the 96 h experimental period. Isolates of Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa and Providencia stuartii were only capable of raising the pH of urine to a maximum of 6.4 and failed to cause crystal deposition in the biofilm. The most effective way to prevent catheter encrustation was shown to be diluting urine and increasing its citrate concentration. This strategy raises the nucleation pH (pH(n)) at which calcium and magnesium phosphates crystallize from urine. Increasing the fluid intake of a healthy volunteer with citrated drinks resulted in urine with a pH(n) of >8.0 in which catheter encrustation was inhibited. It is suggested that this dietary strategy will be an effective means of controlling catheter encrustation, whichever bacterial species is causing the problem.