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PubMed1997

High glutaraldehyde concentrations reduce rather than increase the calcification of aortic wall tissue.

BACKGROUND AND AIMS OF THE STUDY: This study was performed in order to: (i) determine whether a similar reduction of tissue calcification as seen after prolonged storage can be achieved through higher concentrations of glutaraldehyde (GA); and (ii) verify that well-preserved tissue integrity can suppress calcification. METHODS: Before fixation in 0.2% GA (PBS, 4 degrees C, seven days) porcine aortas were kept on ice for 48 h. Alternatively, tissue was immediately fixed at the abattoir in 0.2%, 1.0% or 3% glutaraldehyde (PBS, 4 degrees C, seven days). A second group of immediately fixed tissue (0.2%, 1.0%, 3.0% GA) (PBS, 4 degrees C, two days) had an interim step of L-lysine treatment (0.1M, 37 degrees C, acetic acid buffer, two days) in order to enhance cross-linking followed by warm-temperature fixation (PBS, 37 degrees C, five days). Two animal models were compared: subcutaneous implantation in rats (12 weeks) and vascular implantation in non-human primates, Chacma baboons (six weeks). RESULTS: In both animal models the highest level of calcification was found in the group with delayed fixation in 0.2% GA. In the rat model there was an inverse correlation between tissue calcification and the GA concentration used, with 3% GA-fixed tissue showing the lowest level of tissue calcium. Overall, increasing GA concentration had a significant benefit on calcification (p < 0.0001; two-factor analysis of variance). Enhancement of cross-linking with L-lysine further abrogated tissue calcium levels at all GA concentrations (p < 0.0001; two- factor analysis of variance). Although the short-term baboon model showed lower tissue calcium levels, the trend seen in the rat model was confirmed. CONCLUSIONS: Our results demonstrate the detrimental effect of delayed fixation and further suggest that, against previous beliefs, fixation at higher glutaraldehyde concentrations reduces the calcification tendency of cross-linked aortic tissue.

Abdominal Muscles↗
PubMed1997

[Familial strio-pallido++-dentate calcification].

INTRODUCTION: Calcification of the dentate nucleus of the cerebellum may be seen on cerebral CT in 0.3-0.5% of patients with no symptoms or extra-pyramidal signs. Although there are many causes, some cases show a family incidence. Clinical cases. We present two cases, mother and son, in whom the predominant clinical findings were poor language and a bilateral extrapyramidal syndrome. Laboratory tests, hormone and immunological studies were normal. In both patients cerebral CT showed bilateral calcification of the basal nuclei and dentate nuclei of the cerebellum. DISCUSSION: Our patients fulfilled the clinical and neuro-imaging criteria described in familial strio-pallido-dentate calcification. There is no relationship between the duration and intensity of symptoms, and the extension of the calcification. However, all patients with calcification show clinical features. The predominant features are poor language and a bilateral extra-pyramidal syndrome. These observations indicate that in patients with calcification of the basal ganglia and dentate nuclei of the cerebellum it is necessary to study first degree relatives in order to identify the condition.

Aged↗
PubMed1996

[Cervical intervertebral disc calcification in children: report of 10 patients].

Eleven cervical intervertebral space calcifications were studied in ten children (5 boys, 5 girls), with mean age of 9.4 years. The aetiology, symptoms, roentgenographic clinic features were analyzied. All ten patients showed evidence of calcification of the cervical intervertebral disc. One had calcification in two disc spaces of the cervical spine and associated with subluxation of C1,2. Two patients had calcification protruded into the spinal canal without symptoms of spinal cord compression. One had symptom of nerve root irritation. Eight of ten patients had symptoms which disappeared in two weeks after treatment. Eight patients had been followed over one year. The calcification disappeared from 2 to 8 months. The diagnostic criteria for the syndrome of this study are: (1) pediatric age group only; (2) local or referred pain; (3) limited cervical spine motiion; (4) evidence of inflammation; (5) visible calcification of the cervercal intervertebral disc on roentgenogram; (6) self-limited course; (7) good result after conservative treatment and good prognosis.

Adolescent↗
PubMed1998

[Fetal myocardial calcification (report of 4 cases and review of the literature].

(Report of four cases and review of the literature) Calcification of the myocardium is a rare condition. The cause may be dystrophic or metastatic. An autosomal recessive inherited idiopathic arterial calcification of infancy is more rare abnormality. A dystrophic calcification is the more common of the three and may occur in areas of necrosis, hemorrhage, or fibrosis of the myocardium. Metastatic calcification is associated with hyperparathyroidism, D hypervitaminosis or renal failure, usually accompanied by the deposit of calcium in other organs, particularly the lungs, stomach, kidneys, spleen and liver. Authors report four cases of myocardial calcification diagnosed in intrauterine life. They give a review of literature of fetal and neonatal myocardial calcification.

Adult↗
PubMed1996

Permanent tooth calcification in chimpanzees (Pan troglodytes): patterns and polymorphisms.

Tooth calcification is an important developmental marker for use in constructing models for early hominid life history, particularly for its application to the fossil record. As chimpanzees are commonly utilized in interspecific comparisons in such research, this study aims to improve available baseline data for tooth calcification patterns in chimpanzees (Pan troglodytes), and to quantify basic patterns and polymorphisms. We present an analysis of developmental patterns for the left mandibular dentition (I1-M3) based on intraoral radiographs obtained from a cross-sectional sample of chimpanzees (58 males, 60 females) housed at LEMSIP (NYU Medical Center) and Yerkes (Emory University). No significant differences with previous descriptions of the basic sequences of tooth calcification in chimpanzees were found, but variation in such patterns was documented for the first time. In the overall sequence, polymorphisms between the canine and the group (M2 P4 P3) reached significant levels. This is due to the relative delay in canine crown formation compared to other teeth. Differences in the basic sequence between males and females were recorded, but are due to minor shifts in the percentages of occurrence for polymorphic sequences which are common to both genders. Perhaps our most important findings are that a) different polymorphic sequences occur in tooth calcification and tooth emergence in chimpanzees, and b) developmental relationships among teeth fluctuate throughout tooth calcification. Thus, characterizations of dental developmental patterns based on particular stages of development cannot necessarily be extrapolated to other stages without supporting data.

Animals↗
PubMed1989

Cartilage macromolecules and the calcification of cartilage matrix.

The calcification of cartilage matrix in endochondral bone formation occurs in an extracellular matrix composed of fibrils of type II collagen with which type X collagen is closely associated. Also present within this matrix are the large proteoglycans containing chondroitin sulfate which aggregate with hyaluronic acid. In addition, the matrix contains matrix vesicles containing alkaline phosphatase. There is probably a concentration of calcium as a result of its binding to the many chondroitin sulfate chains. At the time of calcification, these proteoglycans become focally concentrated in sites where mineral is deposited. This would result in an even greater focal concentration of calcium. Release of inorganic phosphate, as a result of the activity of alkaline phosphatase, can lead to the displacement of proteoglycan bound calcium and its precipitation. The C-propeptide of type II collagen becomes concentrated in the mineralizing sites, prior to which it is mainly associated with type II collagen fibrils and is present in dilated cisternae of the enlarged hypertrophic chondrocytes. The synthesis of type II collagen and the C-propeptide, together with alkaline phosphatase, are regulated by the vitamin D metabolites 24,25(OH)2 cholecalciferol and 1,25 (OH)2 cholecalciferol. At the time of calcification, type X collagen remains associated with type II collagen fibrils. It may play a role in preventing the initial calcification of these fibrils focusing mineral formation in focal interfibrillar sites. This process of calcification is clearly very complex, and involves different interacting matrix molecules and is carefully regulated at the cellular level.

Animals↗
PubMed2001

Ultracytochemical study of medullary bone calcification in estrogen injected male Japanese quail.

Fine structural and cytochemical studies were performed to clarify the pattern of medullary bone calcification, specifically in relation to sulfated glycosaminoglycans, by using estrogen-induced medullary bone of male Japanese quails. Tibiae were collected at 4 and 7 days after estrogen treatment. Medullary bone had developed inward toward the marrow cavity, and calcification had begun near the cortical bone and deeper parts of the trabeculae, accompanied by wide osteoid at extending tips and surface areas of the trabeculae. Sulfated glycosaminoglycans, detected by high iron diamine (HID), were distributed in the matrix in a pattern similar to that of calcified matrix of the trabeculae. Cortical bone was negatively stained by HID. In undecalcified specimens, calcified nodules were seen in areas undergoing calcification. Globular structures composed of fine filamentous materials, a marginal dense layer, and central core, were also observed in the matrix of decalcified specimens. Both the calcified nodules and globular structures showed the same distribution pattern, i.e., they were dispersed at surface areas and coalesced in the deeper areas of the matrix. The globular structures were exclusively positive for HID-thiocarbohydrazide-silver protein (HID-TCH-SP) stain, indicating the localization of sulfated glycosaminoglycans. These results strongly suggest that medullary bone calcification progresses by the coalescence of calcified nodules and that sulfated glycosaminoglycans play an important role for the regulation of globular calcification.

Animals↗
PubMed1986

Increased calcification of growth plate cartilage as a result of compressive force in vitro.

The influence of intermittent compressive force (ICF) and of continuous compressive force (CCF) on calcification of growth plate cartilage was investigated, using organ cultures of fetal mouse cartilaginous long bone rudiments. Sixteen-day-old metatarsal rudiments, still consisting of uncalcified cartilage, were isolated and cultured for 5 days. Initial calcification of hypertrophic cartilage occurred under control conditions (atmospheric pressure), and under the influence of ICF or CCF by intermittently or continuously compressing the gas phase above the culture medium. Calcification was monitored by means of 45Ca and 32P incorporation into calcium-phosphate mineral and by morphometric methods. Both ICF and CCF increased cartilage calcification, but ICF was about twice as effective as CCF. Killed rudiments did not calcify during the culture period, nor did ICF or CCF increase the incorporation of label. The effects of ICF and CCF on calcification could not be mimicked by increasing the PO2 and PCO2 levels in the gas phase. The length of the central zone of calcified cartilage was significantly increased by ICF and CCF. We conclude that hypertrophic chondrocytes respond directly to ICF and CCF by an increased deposition of calcium-phosphate mineral in the matrix. Discontinuous mechanical stimulation evokes a higher cellular response than does continuous stimulation.

Animals↗
PubMed2002

Collagen fiber disruption occurs independent of calcification in clinically explanted bioprosthetic heart valves.

The durability of bioprosthetic heart valves (BHV) is severely limited by tissue deterioration, manifested as calcification and mechanical damage to the extracellular matrix. Extensive research on mineralization mechanisms has led to prevention strategies, but little work has been done on understanding the mechanisms of noncalcific matrix damage. The present study tested the hypothesis that calcification-independent damage to the valvular structural matrix mediated by mechanical factors occurs in clinical implants and could contribute to porcine aortic BHV structural failure. We correlated quantitative assessment of collagen fiber orientation and structural integrity by small angle light scattering (SALS) with morphologic analysis in 14 porcine aortic valve bioprostheses removed from patients for structural deterioration following 5-20 years of function. Calcification of the explants varied from 0 (none) to 1+ (minimal) to 4+ (extensive), as assessed radiographically. SALS tests were performed over entire excised cusps using a 0.254-mm spaced grid, and the resultant structural information used to generate maps of the local collagen fiber damage that were compared with sites of calcific deposits. All 42 cusps showed clear evidence of substantial noncalcific structural damage. In 29 cusps that were calcified, structural damage was consistently spatially distinct from the calcification deposits, generally in a distribution similar to that noted in porcine BHV subjected to in vitro durability testing. Our results suggest a mechanism of noncalcific degradation dependent on cuspal mechanics that could contribute to porcine aortic BHV failure.

Animals↗
PubMed1993

Calcification inhibitors in human ligamentum flavum.

To examine the presence of substances which inhibit calcification in human ligamentum flavum, the inhibitory effect of an Na2HPO4 extract of the flavum was determined in terms of the in vitro calcium uptake of the ligamentum flavum matrix. Additionally, grafts of extracted and non-extracted dry ligamentum flavum matrices were transplanted into the dorsal muscles of rats, and calcification in the grafts was examined radiologically and histochemically. In order to determine if component cells of human ligamentum flavum produce calcification inhibitors, ligamentum flavum cells were cultured, and the crystal inhibitor activity of the culture medium was measured by a seed test which used hydroxyapatite as the nucleus of precipitation. The calcification reaction system demonstrated that the ligamentum flavum extract contains an inhibitory factor for calcium uptake by the ligamentum flavum matrix. The seed test revealed that human ligamentum flavum cells produce calcification inhibitor activity.

Adolescent↗
PubMed1978

A macromolecular inhibitor of in vitro calcification of tendon matrix.

Bovine and human tendon tissue do not induce calcification in vitro. However, extraction of those tissues with 3% Na2HPO4 converts them to calcifiable matrices. The supernatant fraction derived from the extraction contains a nondialyzable, perchloric acid soluble component that inhibits calcification of the extracted matrix. This inhibitory substance is characterized by a molecular weight in the range of 85,000-100,000. Exposure to pronase or hyaluronidase did not alter the inhibitory potency but did render the inhibitor dialyzable. Commercial sources of hyaluronic acid, chondrotitin-6-sulfate, chrondroitin-4-sulfate, dermatan sulfate, heparin and lysozyme did not inhibit calcification of the extracted matrix. Phosvitin, a phosphoglycoprotein is a potent inhibitor. Although phosvitin and the tendon extract also inhibit calcification of previously calcified matrix, they have no detectable effect on the rate of decalcification. We conclude that the mechanism of inhibition is characterized by a degree of specificity and that phosvitin and a macromolecular component of tendon tissue blocks conversion of an intermediate matrix-bound CaP complex to crystalline apatite. It seems reasonable that the tendon inhibitor could function in situ and possibly in vivo to control calcification of tendon tissue.

Animals↗
PubMed1977

Initial studies on the crystallinity of the mineral fraction and ash content of isolated human and bovine osteons differing in their degree of calcification.

Several groups containing 10--15 isolated osteons differing in their degree of maturity were analysed. Samples were isolated from undecalcified human and bovine bone sections. The crystallinity coefficient, defined as the ratio of the number of radiation-induced paramagnetic defects in the crystalline lattice of hydroxyapatite to the total ash content, was calculated. The results were compared with measurements performed on fragments of total cortical bone, primary periosteal bone, and inner circumferential lamellar bone. The results show a higher crystallinity of fully calcified osteons as compared with that found at the initial stage of calcification. No differences in the ash content were observed between human osteons, from different stages of calcification evaluated morphologically and by X-ray absorption. These differences were evident when bovine osteons differing in their stage of calcification were compared. Human fully calcified osteons contain 60% ash and their crystallinity coefficient is 52.1. Human osteons at the initial stage of calcification contain 57% ash and their crystallinity coefficient is 40.6. The same parameters for fully calcified bovine osteons and for bovine osteons at the initial stage of calcification are 59% ash, 62.6 crystallinity coefficient and 46% ash, 43.0 crystallinity coefficient, respectively.

Adult↗
PubMed1991

Effect of glass ceramic and titanium implants on primary calcification during rat tibial bone healing.

The effect of bone bonding (KG Cera, Mina 13, and titanium) and nonbone bonding (KGy-213, M 8/1) implants on primary calcification in endosteal bone was examined by comparing changes in the morphometry of matrix vesicles to those occurring during normal bone healing following ablation of rat tibial marrow. The concentration of matrix vesicles, their diameter, and their distance from the calcification front were determined using computerized cytomorphometry at the transmission electron microscopic level. The results demonstrated that bone bonding materials supported an increase in matrix vesicle concentration when compared with control bone at 6 and 14 days postimplantation. At 14 days, there were fewer matrix vesicles in the bone adjacent to the nonbonding implants. Though matrix vesicle diameter decreased in the control bone between 6 and 14 days, it increased in all of the experimental samples. Diameters were significantly greater in the bone bonding samples at 14 days and significantly lower in the nonbonding samples at 6 days. Distance from the calcification front decreased between 6 and 14 days in all groups except in bone adjacent to the KGy-213 implants. In bone adjacent to the bone bonding implants, distance from the calcification front was comparable to or further than that of control bone; in the nonbonding samples it was closer to the calcification front. These results demonstrate that production and maturation of matrix vesicles is influenced in a differential manner by the presence of implant materials.

Animals↗
PubMed2001

Tablet fluoridation influences the calcification of primary tooth pulp.

This study was conducted to determine the influence of long-term tablet fluoridation on primary pulp calcification by light microscopy. Twenty-four caries-free primary molars (after continuous postpartally initiated 1- to 10-year tablet fluoridation) were compared to 17 primary molars of children without fluoride prophylaxis. Pulp calcification in children with tablet fluoridation was significantly more frequent and more pronounced than in untreated children (p = 0.001). Besides the known pulp stones, the prophylaxis group evidenced a special form of calcification consisting of fibrodentin-like hard tissue not observed in the untreated children. These hard tissue bodies developed "intramurally" on the pulp floor and the inside of the dental roots with an irregular extramural spread into the coronal and radicular pulp by displacement and fibrotization of the pulp tissue. Moreover, some of the teeth had more or less extensive areas of interglobular dentin. The affected teeth were ankylosed in the area of the bi- and trifurcation and on the inside of the roots and were thus infra-occluded. Although the duration of tablet fluoridation has no statistically significant influence on pulp calcification, there is a correlation between extensive pulp calcification, postnatally initiated fluoride prophylaxis and the infraocclusion of primary molars.

Child↗
PubMed2000

Calcification and measurements of net proton and oxygen flux reveal subcellular domains in Acetabularia acetabulum.

Vegetative adults of Acetabularia acetabulum (L.) Silva were studied as a model system for subcellular patterning in plants, and a description of several phenotypic and physiological characteristics that reveal patterns of subcellular differentiation in this unicellular macroalga was undertaken. Initially, calcification patterns were studied. Under favorable conditions, the rhizoid and most of the stalk calcified. Only the apical 10-20% of the stalk and a small region adjacent to the rhizoid remained uncalcified. Calcification in algae has been reported to result from a biologically mediated local increase in alkalinity. To test this model extracellular pH and extracellular hydrogen ion gradients were examined with ion-selective, self-referencing, electrodes. In the light, A. acetabulum displayed a general pattern of extracellular alkalinity around the entire alga, although in some individuals the region near the rhizoid and the rhizoid itself displayed extracellular acidity. Acetabularia acetabulum also displayed net hydrogen ion influx at the rhizoid and the apical half of the stalk, variable flux in the lower part of the stalk, and net hydrogen ion efflux at the base of the stalk next to the rhizoid. The lack of complete correlation between external pH patterns and calcification suggests that other factors contribute to the control of calcification in this alga. To examine whether net hydrogen ion flux patterns correlated with photosynthetic or respiration patterns, oxygen flux was measured along the stalk using self-referencing O2 electrodes. Photosynthetic oxygen evolution occurred at comparable levels throughout the stalk, with less evolution in the rhizoid. Respiration mainly occurred near and in the rhizoid, with less O2 consumption occurring more apically along the stalk. Our studies of calcification patterns, net hydrogen ion flux and O2 flux revealed several overlapping patterns of subcellular differentiation in A. acetabulum.

Calcification, Physiologic↗
PubMed1990

Pulp calcifications in primary teeth.

Information regarding the prevalence of pulp calcifications in primary teeth is lacking. The occurrence of pulp calcifications in 120 primary maxillary and mandibular extracted teeth was evaluated radiographically. Twenty-five percent of second molars presented evidence of pulp calcifications; approximately 3% of central incisors were calcified. No other categories of teeth displayed pulp involvement. The low occurrence of pulp calcifications in primary teeth support the view that the occurrence of pulp calcification increases with age.

Age Factors↗
PubMed1999

Histochemical and immunohistochemical analysis of the mechanism of calcification of Meckel's cartilage during mandible development in rodents.

It is widely accepted that Meckel's cartilage in mammals is uncalcified hyaline cartilage that is resorbed and is not involved in bone formation of the mandible. We examined the spatial and temporal characteristics of matrix calcification in Meckel's cartilage, using histochemical and immunocytochemical methods, electron microscopy and an electron probe microanalyser. The intramandibular portion of Meckel's cartilage could be divided schematically into anterior and posterior portions with respect to the site of initiation of ossification beneath the mental foramen. Calcification of the matrix occurred in areas in which alkaline phosphatase activity could be detected by light and electron microscopy and by immunohistochemical staining. The expression of type X collagen was restricted to the hypertrophic cells of intramandibular Meckel's cartilage, and staining with alizarin red and von Kossa stain revealed that calcification progressed in both posterior and anterior directions from the primary centre of ossification. After the active cellular resorption of calcified cartilage matrix, new osseous islands were formed by trabecular bone that intruded from the perichondrial bone collar. Evidence of such formation of bone was supported by results of double immunofluorescence staining specific for type I and type II collagens, in addition to results of immunostaining for osteopontin. Calcification of the posterior portion resembled that in the anterior portion of intramandibular Meckel's cartilage, and our findings indicate that the posterior portion also contributes to the bone formation of the mandible by an endochondral-type mechanism of calcification.

Alkaline Phosphatase↗
PubMed1989

Calcification on chest radiographs: the association with age.

Seven hundred chest radiographs taken in a general hospital were reviewed, 100 (50 men and 50 women) from each of seven decades (3rd to 9th). Each radiograph was examined to determine the site and extent of calcific changes. Prevalence of costal cartilage calcification increased from 6% in the 3rd decade to 45% in the 9th and was commoner in men. Aortic calcification was absent below age 50 and increased from 4% in the 6th decade to 57% in the 9th. Both these trends were statistically significant. Other sites of calcification were found only in patients aged over 70; these included pleural, pericardial, tracheal, myocardial and diaphragmatic calcification.

Adult↗