Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CALCIFICATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,801 records · Page 100Linked to original sources
PubMed1989

Role of lipids in calcification of cartilage.

This review addresses the role of lipids and membranes in biologic calcification and examines their regulation during endochondral ossification. The close association of lipids with mineral deposition has been well established. Early observations indicated that lipids, particularly phospholipids, can not be totally extracted from calcified tissues until the tissues are decalcified. Phospholipids associated with mineral are also enriched in extracellular membrane vesicles, called matrix vesicles. Numerous studies indicate that mineral deposits in calcifying cartilage are first seen in these phosphatidylserine and alkaline phosphatase enriched vesicles and that the process of endochondral calcification of epiphyseal growth plate is possibly mediated by them. Matrix vesicles, and the phospholipids present in them, appear to be involved in initial formation of calcium hydroxyapatite crystals via the interaction of calcium and phosphate ions with phosphatidylserine to form phospholipid:Ca:Pi complexes (CPLX). CPLX is present in tissues which are undergoing initial mineral deposition but are absent from nonmineralizing tissues. Evidence suggests that CPLX resides in the interior of matrix vesicles where the earliest mineral crystals are formed in association with the vesicle membrane. More recently, it has been determined that specific membrane proteins, called proteolipids, participate in CPLX formation and hydroxyapatite deposition, in part by structuring phosphatidylserine in an appropriate conformation. Phosphatidylserine involvement in the initiation of mineralization has been extensively investigated because of its extremely high binding affinity for Ca2+. In addition to structuring a specific phospholipid environment, proteolipids may also act as ionophores, promoting export of protons and import of calcium and phosphate, both requirements of biologic calcification.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1980

Assessment of gestational age of Nigerian newborns using teeth calcification.

The relationship between fetal teeth calcification and gestational age was evaluated in 54 Nigerian newborn chest radiographs. The first deciduous molar was found to calcify at the 33rd week of gestation and the second molar at the 36th week. The pattern of calcification of fetal teeth is no significant difference in teeth calcification between the sexes.

Black People↗
PubMed1989

Immunoreactive calbindin-D9K localization in matrix vesicle-initiated calcification in rat epiphyseal cartilage: an immunoelectron microscope study.

Calbindin-D9K immunoreactivity was localized by electron microscopy in rat calcifying epiphyseal plate cartilage. Antigen-antibody reaction sites were visualized by the presence of protein A-gold complex particles on undecalcified material embedded in Lowicryl K4M. Immunoreactive calbindin-D9K was found in the hyaloplasm of hypertrophic chondrocytes and inside and at the ends of their cell processes. It was localized outside the cells, inside matrix vesicles (MVs), often against the inner face of the delimiting membrane, and inside the trilaminar membrane. Immunoreactive calbindin-D9K appeared to be extruded from the chondrocytes into the matrix vesicles when the latter were formed during the budding of cell processes. In calcifying MVs, gold particles were detected over the needle-shaped crystallites and often over the crystallites lying against the inner leaflet of the vesicular membrane. At a later stage of matrix vesicle calcification after MV membrane disruption, the number of gold particles remained unchanged over the clusters of crystallites at the loci from which the crystallites appeared to have grown and radiated. At a yet more advanced stage of calcification, they remained in the same areas, which were limited to the lateral edges of calcified cartilage longitudinal septa. These results suggest that immunoreactive calbindin-D9K plays a role in calcium input to matrix vesicles and may be involved in matrix vesicle calcification, perhaps in the initial event of matrix vesicle crystal nucleation.

Animals↗
PubMed1986

Ca-ATPase and ALPase activities at the initial calcification sites of dentin and enamel in the rat incisor.

Enzymatic activities of calcium-magnesium dependent adenosine triphosphatase (Ca-ATPase) and nonspecific alkaline phosphatase (ALPase) were localized at the initial calcification sites of dentin and enamel of rat incisor teeth using electron-microscopic cytochemistry. Ca-ATPase was localized in the Golgi cisternae, cytoplasmic vesicles and along the outer surface of the presecretory and secretory ameloblasts, whereas it was totally absent from the odontoblasts in the pulp. Inversely, ALPase reaction was localized along the outer surface of the odontoblasts, but almost completely absent from the ameloblasts. Diffuse extracellular reactions of both enzymes were distributed throughout the unmineralized fibrous matrix of mantle dentin in which a large number of matrix vesicles were scattered. Both Ca-ATPase and ALPase reactions, which appeared in the matrix vesicles in the process of formation of mantle dentin, became most conspicuous at the site of initial dentin calcification. At this stage, an intense Ca-ATPase reaction also appeared along some of the collagen fibrils adjacent to the reactive matrix vesicles. No ALPase reaction was localized along these Ca-ATPase reactive collagen fibrils. Our observations suggest strongly that Ca-ATPase in the matrix vesicles originates from the inner enamel epithelium and/or preameloblasts whereas ALPase originates from the odontoblasts in the pulp. The importance of the coexistence of both enzymes for the control of initial calcification of dental hard tissues is suggested.

Alkaline Phosphatase↗
PubMed1978

X-ray diffraction and electron microscope study of osteons during calcification.

To obtain information on the changes in the inorganic bone fraction during calcification, low- and wide-angle X-ray diffraction techniques and electron microscopy have been applied to single osteon samples. The samples were cylindrically shaped and their axes corresponded to the axes of the Haversian canals. The selection was made according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteon were selected, that is, longitudinally structured osteons, transversely structured osteons, and alternately structured osteons. The results indicate that in osteonic lamellar bone there are two types of inorganic particles: (1) granules arranged in linear or needle-shapred entities with maximum width 40-45 A, which are regularly distributed at the level of the main band of the collagen fibrils where their maximum length reaches the length of the main band itself; that is , about 400 A; and (2) very long crystallites, with a diameter of 40-45 A, which grow with their crystallographic c-axis parallel to the collagen fibrils and cover much more than a major collagen period.

Adolescent↗
PubMed2002

A highly potent 26,27-Hexafluoro-1a,25-dihydroxyvitamin D3 on calcification in SV40-transformed human fetal osteoblastic cells.

26,27-hexafluoro-1a,25-dihydroxyvitamin D3 (F6-D3) has been reported to be 5-10 times more potent than 1a,25-dihydroxyvitamin D3[1,25(OH)2D3] in biological systems in vivo and in vitro. However, the effect of F6-D3 on bone formation has yet to be clarified. In the present study, we investigated the effect of F6-D3 on SV40-transfected human fetal osteoblastic cells (SV-HFO) and found it to be about 100 times greater than that of 1,25(OH)2D3 in stimulating calcification. F6-D3 was also about 100 times more effective than 1,25(OH)2D3 in enhancing the expression of mRNA for alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). In the presence of 10?8 M F6-D3 and 10?6 M 1,25(OH)2D3, the calcification began on day 9 and increased up to day 19. Expression of mRNA for ALP and OCN reached a maximum on day 4 and thereafter declined. On the other hand, when osteoblastic cells were incubated with a low level of [1b-3H]-F6-D3- or [1b-3H]-1,25(OH)2D3, each radioactive peak could not be detected. However, on the incubation of osteoblastic cells and radioactive substrate in the presence of ketoconazole, a selective inhibitor of CYP24, a clear peak for each substrate was detected. This suggested that F6-D3 as well as 1,25(OH)2D3 is metabolized by CYP24. Osteoblastic cells were incubated with 10?8 M[1b-3H]-F6-D3 or 10?8 M[1b-3H]-1,25(OH)2D3 for 4, 9, and 14 days. A small peak of 1,25(OH)2D3 was observed and thereafter its level decreased. In addition, two unknown peaks increased when the culture period was extended. In the case of F6-D3, peaks of F6-D3 and 26,27-hexafluoro-23-oxo-1a,25(OH)2D3(23-oxo-F6) were clearly detected, the latter being about 4 times higher than the former. Both peaks was retained up to day 14. The amount of unlabeled F6-D3 and 23-oxo-F6 calculated from the specific radioactivity in the cells may be similar to the amount of 1,25(OH)2D3 and its metabolites. The strong activity of F6-D3 in stimulating calcification may be due to the fact that F6-D3 is much more potent than 1,25(OH)2D3 in enhancing the expression of mRNA for ALP, OCN, and OPN and that the amount of F6-D3 and 23-oxo-F6 accumulated in the cells is much greater than that of 1,25(OH)2D3 and its metabolite.

Alkaline Phosphatase↗
PubMed2006

Site-specific in vivo calcification and osteogenesis stimulated by bone sialoprotein.

Bone sialoprotein (BSP) is one of the major non-collagenous glycosylated phosphoproteins of the extracellular matrix in bone. In vitro studies suggest that BSP may play important roles in the initiation and/or growth of calcium-phosphate crystals. To investigate the potential role of BSP in more complex in vivo environments, we implanted purified bovine BSP with type-I collagen as a carrier into surgically created rat calvarial defects and thoracic subcutaneous pouches. The responses to the implants were assessed by histochemistry, immunohistochemistry, in situ hybridization, quantitative real-time PCR, and biochemical analyses. BSP-collagen, but not collagen alone, elicited mineral deposition in the matrix of proliferating cells near the dura at days 4-5 followed by osteoblast differentiation and synthesis of new bone in the mid-portion of the calvarial defects. In contrast, implantation of BSP-collagen into subcutaneous pouches did not induce calcification or osteogenesis over the same experimental period. We explored the underlying mechanisms for the site-specific responses to BSP-collagen implants and found that higher levels of calcium content and alkaline phosphatase activity at the cranial site at days 2-5 were associated with the BSP-mediated calcification. We also found that BSP stimulated osteoblast differentiation through up-regulation of cbfa1 and osterix, key transcription factors of osteoblast differentiation, which occurred in the calvarial defects but not in the subcutaneous tissue. These results demonstrate that BSP stimulates calcification and osteogenesis in a site-specific manner, and that local environment and the specificities of responding cells may play critical roles in the function of BSP in vivo.

Alkaline Phosphatase↗
PubMed2000

Matrix vesicle calcification in bones of adult rats.

To clarify the calcification mechanism that functions in bone formation in adult rats, the ultrastructure of tibial trabeculae and calvarial endostea obtained from 8- to 18-month-old rats was investigated morphologically, and compared with that of 19.5-day post-coitum fetal rats. In both samples, osteoid was observed between the activated osteoblasts and the calcified matrix, which contained matrix vesicles enclosed by a biological membrane. Some of these vesicles contained needle-like crystals thought to be hydroxyapatite, suggesting probable matrix vesicle calcification. These results indicate that matrix vesicle function not only in the initial calcification that occurs during embryonic ossification but also contribute to bone formation in adults.

Animals↗
PubMed2006

In vivo light-microscopic documentation for primary calcification processes in the hermatypic coral Stylophora pistillata.

Skeletogenesis in the hermatypic coral Stylophora pistillata was studied by using the lateral skeleton preparative (LSP) assay, viz., a coral nubbin attached to a glass coverslip glued to the bottom of a Petri dish. Observations on tissue and skeletal growth were made by polarized microscopy and by using vital staining. The horizontal distal tissue edges developed thin transparent extensions of ectodermal and calicoblastic layers only. Four stages (I-IV) of skeletogenesis were observed at these edges, underneath the newly developed tissue. In stage I, a thin clear layer of coral tissue advanced 3-40 microm beyond the existing LSP peripheral zone, revealing no sign of spiculae deposition. At stage II, primary fusiform crystals (1 microm each) were deposited, forming a primary discontinuous skeletal front 5-30 microm away from the previously deposited skeleton. During stage III, needle-like crystals appeared, covering the primary fusiform crystals. Stage IV involved further lengthening of the needle-like crystals, a process that resulted in occlusion of the spaces between adjacent crystals. Calcification stages I-III developed within hours, whereas stage IV was completed in several days to weeks. Two basic skeletal structures, "scattered" and "laminar" skeletons, were formed, integrating the growth patterns of the needle-like crystals. High variation was recorded in the expression of the four calcification stages, either between different locations along a single LSP or between different preparations observed at the same diurnal time. All four skeletogenesis stages took place during both day and night periods, indicating that an intrinsic process controls S. pistillata calcification.

Animals↗
PubMed2003

Matrix vesicles and calcification.

Matrix vesicles (MVs) are extracellular, 100 nM in diameter, membrane-invested particles selectively located at sites of initial calcification in cartilage, bone, and predentin. The first crystals of apatitic bone mineral are formed within MVs close to the inner surfaces of their investing membranes. Matrix vesicle biogenesis occurs by polarized budding and pinching-off of vesicles from specific regions of the outer plasma membranes of differentiating growth plate chondrocytes, osteoblasts, and odontoblasts. Polarized release of MVs into selected areas of developing matrix determines the nonrandom distribution of calcification. Initiation of the first mineral crystals, within MVs (phase 1), is augmented by the activity of MV phosphatases (eg, alkaline phosphatase, adenosine triphosphatase and pyrophosphatase) plus calcium-binding molecules (eg, annexin I and phosphatidyl serine), all of which are concentrated in or near the MV membrane. Phase 2 of biologic mineralization begins with crystal release through the MV membrane, exposing preformed hydroxyapatite crystals to the extracellular fluid. The extracellular fluid normally contains sufficient Ca2+ and PO4(3-) to support continuous crystal proliferation, with preformed crystals serving as nuclei (templates) for the formation of new crystals by a process of homologous nucleation. In diseases such as osteoarthritis, crystal deposition arthritis, and atherosclerosis, MVs initiate pathologic calcification, which, in turn, augments disease progression.

Bone Matrix↗
PubMed1990

Production of endothelial cell stimulating angiogenesis factor (ESAF) by chondrocytes during in vitro cartilage calcification.

The aim of this study was to identify the stimulus for production of the latent collagenase and angiogenic activator ESAF by growth plate chondrocytes. Stimulation correlated most closely with matrix calcification. Alkaline phosphatase was necessary for calcification (and so stimulation of ESAF production) but we could find no evidence for a direct link with ESAF production. ESAF production was also stimulated by addition of preformed mineral to non-calcified cultures but was inhibited by dexamethasone. Protein synthesis was necessary for the stimulation of ESAF production by calcification, though ESAF is not itself a protein. Based on these findings we suggest that chondrocytes, at a suitable stage of maturation in the growth plate, are stimulated to produce ESAF by the proximity of crystals in the matrix. Stimulation, which may consist of the induction of an enzyme or transport protein, leads to the release of this potent activator of collagenolysis as part of the angiogenic cascade.

Alkaline Phosphatase↗
PubMed1981

Transplacental effects of cortisone acetate on calcification and ossification of long bones in mice.

The transplacental effects of cortisone acetate on the skeleton of neonatal mice has been investigated. Pregnant mice were injected intramuscularly with 0.75 mg cortisone acetate daily on days 11-19 of gestation. The mice were allowed to deliver and pups were weighed on days 1, 3, 5, 10, 15, 20 and 30 and compared to controls. Light microscopy of non-decalcified longitudinal sections of bones revealed mineral precipitates throughout the zone of hypertrophic cartilage most prominent on days 1, 3 and 5 and gradually disappearing on days 10-20. Transmission electron microscopy revealed intracellular calcification of maturing and hypertrophic chondrocytes in addition to abnormal calcification of the interstitial substance. Hydroxylapatite crystals were not necessarily associated with matrix vesicles. Scanning electron microscopy of long bones revealed a wide zone of calcified intercartilagenous matrix representing the calcified proliferating and hypertrophic zones. In this area, the calcospherites varied in size (0.5-1.4 mu in diameter) and were found in both longitudinal and transverse septa. No significant differences in the distribution and shape of cartilage matrix vesicles between experimental and control animals was observed. However, the fact that mineral crystals in experimental animals was not necessarily associated with matrix vesicles points to the possibility that this "pathological calcification" may utilize a different mechanism than the normal process through matrix vesicles.

Animals↗
PubMed1981

Clinical significance of basal ganglia calcifications detected by ct (a retrospective study of 33 cases).

In a retrospective study 2015 CT scans were studied for the presence of basal ganglia calcifications. These were discovered in 33 cases. No abnormalities in serum calcium or phosphate levels or any other specific clinical symptoms related to these calcifications were found. It is concluded that basal ganglia calcifications casually detected by CT generally have no clinical significance.

Adult↗
PubMed1988

Costal cartilage calcification pattern--a clue for establishing sex identity.

Radiological study of costal cartilage calcification patterns in establishing the sex identity is conducted in Southern Indians. Three major patterns of calcification capable of establishing sex identity were noticed. Calcification was not observed below the ages of sixteen years in the female and twenty years in the male. This, though seriously limits the applicability of the method to age groups of sixteen and twenty years and above in the female and male sexes respectively, the ease, rapidity and relative inexpensiveness of the procedure in both living as well as dead and decomposed, requiring little expertise, recommends its use especially where a forensic expert is readily not available.

Adolescent↗
PubMed1986

A study of calcification in the leg tendons from the domestic turkey.

Details are presented of the structure and the spatial and temporal sequence of calcification within leg tendons obtained from the domestic turkey, Meleagris gallopavo. Histological and ultrastructural examination of the tissues reveals the development of large tendonoblasts, disposed in columns parallel to tendon long axes. Maturing cells are characterized by organelles active in protein synthesis, few mitochondrial granules, and an extensive system of processes. Deposition of mineral in the extracellular tissue spaces appears initially associated with small vesicular structures located between collagen fibrils. As calcification progresses, mineral is associated predominantly with collagen. Electron diffraction and electron probe microanalysis indicate that the mineral is a poorly crystalline hydroxyapatite having a Ca/P molar ratio ranging between 0.9 and 1.5. Following decalcification and staining of tissue sections, vesicular structures retain integrity by uptake of lead and uranium salts while collagen stains only poorly. Implications of these results are discussed with respect to the physicochemical and biological events of vertebrate calcification.

Animals↗
PubMed1991

Aldehyde tanning: the villain in bioprosthetic calcification.

Preservation of bioprosthetic valves may play a role in valvular calcification. Subcutaneous implants in rats were used to test the effect of different preservation solutions. Fifty male Sprague-Dawley rats were divided into five groups. Fresh bovine pericardium was treated in one of five ways: group A: 99.5% glycerol for 1 week; group B: as group A, then normal saline wash and 0.25% formaldehyde storage for 24 h; group C: as group A, then normal saline wash and 4% formaldehyde storage for 24 h; group D: as group A, then normal saline wash and 0.625% glutaraldehyde storage for 24 h; group E: 0.625% glutaraldehyde and 4% buffered formaldehyde storage. Treated bovine pericardium was cut into 1-cm2 pieces and washed for 30 min with normal saline before implantation. In each animal, three pieces were implanted in the subcutaneous tissue of the back. After 70 days, retrieved specimens were examined grossly, and X-ray densitometry, calcium analysis, and histological examinations were carried out. The results showed that glycerol-treated tissue (group A) had less calcification (calcium 6.92 +/- 4.46 micrograms/mg dry weight) than other groups: group B (calcium 323.12 + 63.56 micrograms/mg dry weight); group C (calcium 240.65 + 13.47 micrograms/mg dry weight); group D (calcium 232.29 + 13.01 micrograms/mg dry weight). These differences were markedly significant (p less than 0.0001). It appears that aldehydes play an important role in the calcification of bioprosthetic valves. Experience with glutaraldehyde- and glycerol-treated pericardium in valvular applications in sheep support these observations.

Animals↗
PubMedDate not supplied

Systematic assessment of bone resorption, collagen synthesis, and calcification in chick embryonic calvaria in vitro: effects of prostaglandin E2.

A systematic method has been developed to assess bone resorption, matrix formation, and calcification in a single calvarial culture from 20-day-old chick embryos. The bones were prelabeled with 45Ca by an injection into the egg white before culture. In the last 2 h of incubation, the bones were further labeled with both 3H-proline and 3H-tetracycline. Bone resorption was assessed as 45Ca release into the medium. Collagen synthesis was measured by the incorporation of 3H-proline into collagenase-digestible protein (CDP). Since tetracycline has been commonly used as an in vivo marker for osteoid calcification, we assessed in vitro calcification as the uptake of 3H-tetracycline into bone. By using this method, we studied the effects of prostaglandin E2 (PGE2) and indomethacin, which inhibits biosynthesis of PGE2, on bone resorption and formation. The cultured bone synthesized approximately 300 ng of PGE2 during every 24 h of incubation, and indomethacin (10(-6) M) completely inhibited the synthesis. In indomethacin-treated cultures, % 45Ca release and the labeling of CDP were significantly reduced. These reductions were not seen when exogenous PGE2 (10(-9) M) comparable to its endogenous level was added along with the indomethacin. Furthermore, 10(-8) to 10(-5) M PGE2 increased % 45Ca release and the CDP labeling. In addition, the uptake of 3H-tetracycline into the cultured bone was also enhanced by PGE2. In devitalized calvaria, PGE2 had no effect on 3H-tetracycline uptake, suggesting that the stimulative effect on PGE2 was cell-mediated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2026

Perinatal Diagnosis of Generalized Arterial Calcification of Infancy: First Genetically Confirmed ENPP1 Case in an Egyptian Fetus.

Generalized Arterial Calcification of Infancy (GACI) is a rare genetic vascular disease characterized by the early onset (between in utero and infancy) of extensive calcification and stenosis of the large and medium-sized arteries. Presentation is typically with respiratory distress, congestive heart failure, and systemic hypertension. With approximately 300 cases reported worldwide in the medical literature. The prevalence is unknown; however, based on the carrier frequency of the recognized pathogenic variants, a frequency of 1 in 200,000 has been suggested. The autosomal recessive form of GACI disorder is caused by mutations in the ENPP1 or ABCC6 genes. To the best of our knowledge, this study represents the first genetically confirmed case of GACI in an Egyptian fetus detected during the perinatal period. In this report, we describe a case of GACI in a fetus with a pathogenic ENPP1 gene mutation at 29 weeks of gestation. Ultrasound examination revealed aortic and pulmonary valve stenosis, biventricular hypertrophy, and a hypercalcified aorta and ductal arch. Genetic testing identified a homozygous pathogenic variant in the ENPP1 gene: c.749C>T (p.Pro250Leu). In conclusion, early diagnosis of GACI is vital due to its severe prognosis and early symptom onset. Expert fetal echocardiography plays a key role in detecting arterial calcification during pregnancy. Genetic testing enhances diagnostic accuracy, informs treatment strategies, and supports family counselling.

Arterial calcification↗

Refine your search to explore more results.