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Biomedical subjects

M D Grynpas

Publications and source records attributed to M D Grynpas.

At least 91 records · Page 5Linked to original sources
PubMed1988

Fluoride reduces the rate of dissolution of bone.

Recently, fluoride has been used in the treatment of osteoporosis in an attempt to rebuild bone lost due to this disease. Fluoride has been shown to have a profound effect on osteoblasts and bone formation. Studies have shown that synthetic fluorapatite is more stable and less soluble than hydroxyapatite. This study was designed to determine the dissolution properties of bones from rats fed a normal diet versus rats fed a high fluoride diet. Intact and deproteinized bones were dissolved in buffered solutions, containing physiological amounts of inorganic Ca and P, at pH 3.4, 4.4 and 5.4. The data demonstrate that fluoridated bones dissolve slower than normal bones, deproteinized bones dissolve faster than intact bones and that the initial rate of dissolution of fluoridated bone is always significantly lower than that of normal bone. This may help to explain the reduced rate of osteoclastic resorption in patients undergoing fluoride therapy.

Animals↗
PubMed1988

Crystal associated diseases: role of scanning electron microscopy in diagnosis.

As crystals are important etiologic agents for disease, their accurate identification in tissues and body fluids is of utmost importance. This paper surveys the roles of crystals in disease process and outlines current analytical techniques for crystal detection and identification in bone tissues. The value of multiple correlated techniques is demonstrated including scanning electron microscopy, x-ray energy spectroscopy and powder diffraction analysis. The current feasibility of utilizing intermediate voltage scanning transmission analytical electron microscopy to integrate these analytical techniques on the same tissue sample is emphasized.

Body Fluids↗
PubMed1988

Changes in quality of bone mineral on aging and in disease.

This paper reviews the changes in the quality of bone mineral with age and in disease. After a brief review of morphological changes with aging in mammalian bones, microradiography is compared to backscattered electron imaging and their use in bringing out subtle changes in bone mineralization outlined. Changes in the quality of bone with disease is described using osteoporosis as an example. Chemical changes in the skeleton are then discussed and related to morphological changes. Finally, some examples of localized and generalized changes in bone mineral are given. This paper emphasizes that understanding the nature of the mineral phase in bone as well as its heterogeneity and its changes with age and in disease is essential to the elucidation of skeletal physiology and pathology.

Adult↗
PubMed1987

Effect of synthetic calcium pyrophosphate and hydroxyapatite crystals on the interaction of human blood mononuclear cells with chondrocytes, synovial cells, and fibroblasts.

Synthetic calcium pyrophosphate dihydrate crystals and, to a lesser extent, synthetic hydroxyapatite crystals increased the amount of interleukin-1/mononuclear cell factor released by human blood monocytes, as measured by collagenase and prostaglandin E2 production by rabbit chondrocytes, human dermal fibroblasts, and adherent rheumatoid synovial cells. The same crystals also directly induced collagenase and prostaglandin E2 secretion by rabbit chondrocytes, and potentiated the action of interleukin-1/mononuclear cell factor on chondrocytes. These mechanisms may be important in the pathogenesis of the destructive arthropathies associated with these crystals.

Animals↗
PubMed1987

Bone mineral in the castrated rat model of osteopenia.

The effects of castration on cortical bone structure and chemistry were studied in male Wistar rats of two age groups, 8 and 24 months. Some rats were castrated and some were sham operated (control) in each group. All animals were killed after 4 months. Although no changes in serum chemistry, bone chemistry, or bone histology could be found, the young castrated animals versus controls showed less density of bone mineral as determined by the density fractionation technique and smaller crystallite size of mineral particles as determined by x-ray diffraction line-broadening analysis. These changes, indicative of less mature bone formation, were not observed in mature castrated or control rats despite a decreased amount of bone compared with young rats. In this model, castration appears to affect bone mineral quality in young but not in old animals.

Age Factors↗
PubMed1987

Effect of glycosaminoglycans on calcium pyrophosphate crystal formation in collagen gels.

Formation of calcium pyrophosphate dihydrate (CPPD) crystals in native collagen gels represent an in vitro model system for the study of pathological cartilage calcification. The conditions under which CPPD forms in collagen gels have been determined. At low Ca X pyrophosphate product, CPPD forms directly. At high Ca X pyrophosphate product, CPPD forms via the amorphous intermediate calcium magnesium pyrophosphate (CMPP). Chondroitin sulfate (CS) inhibits formation of CPPD by both pathways, but apparently by different mechanisms. Direct CPPD formation is inhibited with low potency by CS, apparently by binding of Ca2+ ions. Indirect formation of CPPD is inhibited with high potency by CS, apparently by stabilization of the CMPP intermediate. Comparison of the inhibition of direct CPPD formation by the two glycosaminoglycan species occurring in cartilage proteoglycan showed that CS is a more potent inhibitor than keratan sulfate (KS), in agreement with the greater Ca2+-binding affinity of CS. The increase in KS/CS ration which occurs in human hyaline cartilage with aging may facilitate deposition of CPPD crystals by decreasing the exclusion of pyrophosphate anions.

Calcium Pyrophosphate↗
PubMed1987

Osteoarthritic cartilage contains increased calcium, magnesium and phosphorus.

Using plasma emission spectroscopy, we measured the calcium (Ca), phosphorus (P), magnesium (Mg), and sulphur (S) concentration in femoral head cartilage from 7 patients with osteoarthritis (OA) and 22 normal patients. We found that in OA cartilage Ca = 271.9 +/- 32.7 mmol/kg dry weight compared to Ca = 113.2 +/- 12.6 mmol/kg dry weight in normal controls. The Ca:P molar ratio in OA cartilage was 1.93 compared to Ca:P = 2.27 in normals, and Ca:P = 1.67 in apatite crystals. We conclude that OA cartilage has a greater binding capacity for Ca, Mg, and P than does normal cartilage. Apatite crystals, if present, comprise maximally 0.4% wet weight of OA cartilage.

Adolescent↗
PubMed1986

The changes in quality of mandibular bone mineral in otherwise totally immobilized rhesus monkeys.

The status of bone mineral and osteocalcin in the young adult Rhesus monkey mandible was assessed following a 14-day period of postcranial immobilization, and after 7- and 28-day recovery periods. Specimens of cortical bone taken from the compact bone at the inferior border of the jaws were ground in liquid nitrogen and sieved to a particular size below 20 micron. The bone powder was then fractionated in a bromoform-toluene density gradient to determine its mineralization profile (Ca, P, CO3, and osteocalcin), and X-ray diffraction was used to determine apatite crystal size in some fractions. There was no change in the chemistry of the mandibular bone from the immobilized animals. However, the mineralization profile in that group showed a significant shift toward the higher density fractions, indicating the presence of a greater than normal content of mature well-mineralized bone. While this trend was accentuated in the jaws following a 7-day postimmobilization recovery period, partial recovery of the normal profile was observed after a 28-day recovery period. The osteocalcin profile shifted like the mineralization profile during the immobilization and recovery periods. X-ray diffraction analyses showed that the shift in the mineralization profile during the immobilization period was associated with a decrease in apatite crystal size.

Animals↗
PubMed1986

Bone maturation and quality of bone material in rats flown on the space shuttle 'Spacelab-3 Mission'.

The maturation profiles of calcium, phosphorus, magnesium and hydroxyproline in the femoral trabecular and cortical bone and in the thoracic vertebrae from male rats flown on the 7-day 'Spacelab-3 Mission' were measured by density gradient analysis. In rats exposed to a spaceflight environment, profiles of the matrix and mineral moieties were shifted toward both the lower (vertebrae) and higher density fractions (femurs and vertebrae), patterns indicating a decrease in bone growth/turnover. X-Ray diffraction of vertebrae indicated that spaceflight is associated with a decrease in apatite crystal size/perfection.

Animals↗
PubMed1985

Inhibition of hydroxyapatite formation in collagen gels by chondroitin sulphate.

Crystal growth in native collagen gels has been used to determine the role of extracellular matrix macromolecules in biological calcification phenomena. In this system, type I collagen gels containing sodium phosphate and buffered at pH 7.4 are overlayed with a solution containing CaCl2. Crystals form in the collagen gel adjacent to the gel-solution interface. Conditions were determined which permit the growth of crystals of hydroxyapatite [Ca10(PO4)6(OH)2]. At a Ca/P molar ratio of 2:1, the minimum concentrations of calcium and phosphate necessary for precipitation of hydroxyapatite are 10 mM and 5 mM, respectively. Under these conditions, precipitation is initiated at 18-24h, and is maximal between 24h and 6 days. Addition of high concentrations of chondroitin 4-sulphate inhibits the formation of hydroxyapatite in collagen gels; initiation of precipitation is delayed, and the final (equilibrium) amount of precipitation is decreased. Inhibition of hydroxyapatite formation requires concentrations of chondroitin sulphate higher than those required to inhibit calcium pyrophosphate crystal formation.

Calcium↗
PubMed1984

Failure to detect an amorphous calcium-phosphate solid phase in bone mineral: a radial distribution function study.

X-ray diffraction radial distribution function analysis was used to determine if a significant amount of an amorphous solid phase of calcium phosphate exists in bone, and if so, whether the amount varies as a function of age and maturation. Unfractionated cortical bone from embryonic and posthatch chicks of various ages and a low-density fraction of embryonic bone were studied. No evidence was found for the presence of an amorphous solid phase of calcium phosphate in any of the samples studied, including the recently deposited bone mineral of the low density fraction of embryonic bone. As little as 12.5% of synthetic amorphous calcium phosphate (ACP) added to bone was readily detected by the radial distribution function technique used. The results clearly indicate that the concept that ACP is the initial solid mineral phase deposited in bone, and the major mineral constituent of young bone is no longer tenable. The concept does not provide an accurate description of the nature of the initial bone mineral deposited, or the changes that occur with maturation, nor can it account for the compositional and X-ray diffraction changes that the mineral component undergoes during maturation and aging.

Age Factors↗
PubMed1984

Failure to detect crystalline brushite in embryonic chick and bovine bone by X-ray diffraction.

We have reexamined the question of whether brushite (CaHPO4 X 2H2O) occurs in embryonic bone. On the basis of the experiments reported here, and a reexamination of data previously obtained in this laboratory, we have concluded that crystalline brushite as a separate phase identifiable by X-ray diffraction does not occur in embryonic chick or bovine bone. Crystalline brushite previously identified in this laboratory in the less-mineralized fractions of embryonic chick bone was apparently formed artifactually during the fractionation process, possibly from preexisting domains of HPO4(-2) groups in a noncrystalline brushite-like configuration.

Animals↗
PubMed1984

Milk of calcium: a structural study.

Milk of calcium is an unusual radiologic entity which covers a wide variety of stones of various compositions. They only have in common the fact that in vivo stone movement is indicated by radiologic pictures taken at different postures of the patient. Despite over 100 cases reported in the literature, no comprehensive structural and chemical analyses have been published. In our case the milk of calcium stones were found to be composed of large crystals of calcium oxalate mono and dihydrates on which clusters of small apatite needles were deposited.

Calcium Oxalate↗
PubMed1983

X-ray diffraction studies of the crystallinity of bone mineral in newly synthesized and density fractionated bone.

The crystallinity of bone mineral at different stages of maturation has been measured by quantitative X-ray diffraction methods. Crystallinity measurements were made on tibial mid-diaphyses from 17-day embryonic chicks, newly-formed periosteal bone from embryonic chicks, and density-fractionated bone from post-hatch chickens from 5 weeks to 2 years of age. For a given animal age and degree of mineralization, crystallinity increases with animal age, indicating that changes in bone mineral occur even after mineralization is complete or nearly complete.

Age Factors↗
PubMed1980

Collagen type II differs from type I in native molecular packing.

Native molecular packing of types I and II collagens were compared by low-angle X-ray diffraction. Fibers from human intervertebral disc that contained different proportions of types I and II collagens were studied by X-ray diffraction, and were then analyzed biochemically to measure the constituent collagen species. Other cartilages, containing exclusively type I or type II collagen, were also examined. The equatorial diffraction established that in wet, native type II collagen, the molecules are spaced farther apart laterally than in type I collagen under the same conditions. For the disc the average lateral spacing ranged from about 14 A for a fiber from the outer annulus fibrosus containing mostly type I collagen, to 16-17 A for nucleus pulposus that contained all type II collagen. No differences were evident among dried specimens. We have also found that the meridional diffraction pattern from dry fibers of type II collagen differed from that of type I collagen. The findings indicate that under physiological conditions type II collagen fibrils contain more water than type I fibrils. Calculations suggest 50-100% more water. We propose that this difference is an inherent property of type II collagen and that it may be significant for the function of type II collagen in tissues that dissipate compressive forces. The content of glycosylated hydroxylysine residues is the chemical variable likely to be modulating fibrillar hydration.

Adolescent↗