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Biomedical subjects

G Boivin

Publications and source records attributed to G Boivin.

At least 127 records · Page 7Linked to original sources
PubMed1985

Histological study of a case of recurrent olecranon bursitis with mixed calcium pyrophosphate dihydrate and apatite crystal deposits.

This is the report of a light and transmission electron microscopic study of an olecranon bursitis and of the adjacent distal tricipital tendon in an 83 year-old man. The data are compared with those of a similar study in the same patient performed 2 years ago. Calcium pyrophosphate dihydrate crystals were observed in the bursal fluid, in the inner part of the bursal wall (extracellular localization and intracellular phagocytosis) as well as in the peripheral part of the tendon. In addition, small apatite deposits were observed in the bursa and tendon by electron microscopy. The origin of these bursal deposits is discussed; it is suggested that they may be related to an exchange from the tendon to the remodelled bursal wall.

Aged↗
PubMed1985

Distribution of fluoride in calcified cartilage of a fluoride-treated osteoporotic patient.

Subchondral bone and calcified cartilage from a femoral head of a 74-year-old osteoporotic woman treated for 30 months with sodium fluoride were analyzed. The fluoride content of the calcified tissues was determined by a specific ion electrode, and the topographic distribution pattern of fluoride was determined with an electron microprobe. The fluoride content in calcified cartilage (0.39% of ash) was higher than in neighboring subchondral bone (0.28% of ash). Line scan and X-ray images indicated a high concentration of fluoride in the outer layer of calcified cartilage lining the uncalcified cartilage, as well as in the inner layer of the subcortical endosteal bone. This study shows that calcified cartilage is an important site of fluoride deposition, and suggests that the accumulation of fluoride is related to the calcification process.

Aged↗
PubMed1983

Bilateral fractures of femoral neck in patients with moderate renal failure receiving fluoride for spinal osteoporosis.

Two patients with moderate renal failure sustained spontaneous bilateral hip fractures during treatment with fluoride, calcium, and vitamin D for osteoporosis. They had been taking sodium fluoride (40-60 mg/day) for 11 and 21 months, respectively. Histological examination of a specimen of the bone showed severe fluorosis in the first case, and quantitative analysis of bone showed osteomalacia and skeletal fluorosis in the other case. These abnormalities were considered to be the consequence of excessive retention of fluoride due to renal insufficiency. As bilateral femoral neck fractures are very rare these data suggest a causal link between fractures and fluoride in patients with renal failure. Thus fluoride should be given at a lower dosage, if at all, to patients with even mild renal failure.

Aged↗
PubMed1983

An ultrastructural study of articular chondrocalcinosis in cases of knee osteoarthritis.

A study was made by transmission electron microscopy of tissue specimens (cartilage, meniscus and synovial membrane) taken from 5 knees presenting radiological and anatomical signs of articular chondrocalcinosis and osteoarthritis. It was part of a broader study which included analysis of the same specimens by macroscopy and light microscopy as well as by X-ray diffraction of the mineral deposits. In cartilage and meniscus juxta-cellular calcium pyrophosphate dihydrate (CPPD) crystals of variable sizes were observed in the extracellular organic matrix, independent of the collagen fibrils. They occurred mainly in the superficial and middle zones but could also be seen intermingled with the apatite crystals in the cartilage calcified zone. In synovial membrane most of the CPPD crystals were extracellular but some of them could be seen in cytoplasmic phagocytic vacuoles. These observations are in agreement with those in the literature regarding the ultrastructural picture of chondrocalcinosis and support the thesis that the crystals originate in the cartilage and are phagocytized in the synovial membrane. Although the results of the present study do not provide direct evidence of a relationship between chondrocalcinosis and osteoarthritis, the data of the ultrastructural investigation appear nevertheless of great interest as a complement to the data furnished by light microscopy.

Adult↗
PubMed1983

Calcergy and calciphylaxis: timed appearance of gamma-carboxyglutamic acid and osteocalcin in mineral deposits.

gamma-Carboxyglutamate (Gla), a calcium binding amino acid whose synthesis depends on vitamin K, has been found in association with pathologic calcifications. It is of interest therefore to examine the role of Gla-containing proteins in the formation of nonskeletal mineralized tissues. Calcergy and calciphylaxis, experimentally induced models of pathologic calcification, offer the opportunity to study the formation of mineral deposits in the absence of an endochondral sequence of bone formation. Before induction of subcutaneous calcinosis by topical treatment with the direct calcergen, KMnO4, or by challenging dihydrotachysterol-sensitized animals with FeCl2, control specimens contain no gamma-carboxyglutamic acid. With the initial formation of cytoplasmic vesicles, calcium content of the tissues increases and Gla is detected. Gla levels are further elevated with the appearance of poorly crystalline apatite-like crystallites. Origin of protein bound Gla was established by positive identification of osteocalcin by radioimmunoassay. Gla and osteocalcin appear concomitant with the earliest mineral deposits observed by electron microscopy and micro X-ray analysis. The formation of organized extracellular pattern by X-ray diffraction allowed sufficient mineral accumulation for detection with calcium, Gla, and osteocalcin increasing allowed sufficient mineral accumulation for detection of an apatite-like pattern by X-ray diffraction with calcium, Gla, and osteocalcin increasing proportionately as mineral is deposited.

1-Carboxyglutamic Acid↗
PubMed1983

Ultrastructural aspects after cryoultramicrotomy of bone tissue and sutural cartilage in neonatal mice calvaria.

Using transmission electron microscopy after cryoultramicrotomy, mineralized as well as unmineralized bone tissues and sutural cartilage were observed in neonatal mice calvaria. A good definition of osteoblasts (nucleus, membranes, organelles) and extracellular constituents (collagen fibrils, matrix vesicles, mineral substance) was obtained. The sutural zone was composed of an unmineralized cartilaginous tissue with more or less hypertrophic cells surrounded by a finely fibrillar matrix.

Animals↗
PubMed1982

Olecranon bursitis related to calcium pyrophosphate dihydrate crystal deposition disease.

A case of olecranon bursitis in an 81-year-old patient is presented. Analysis of the bursal fluid revealed positive birefringent crystals; radiographs showed calcifications in the distal triceps tendon. A bursectomy was performed. X-ray diffraction analyses demonstrated calcium pyrophosphate dihydrate patterns in a subcutaneous "tophus" and in a specimen of the tendon. On histologic examination, there was a bursitis with positive birefringent crystals on the bursa's inner surface; histologic images of "chondrocalcinosis" were observed in and around the tendon. It is concluded that bursitis may be part of the extraarticular manifestations of calcium pyrophosphate dihydrate crystal deposition disease.

Aged↗
PubMed1982

Biochemical findings in blood of aged patients with femoral neck fractures: a contribution to the detection of occult osteomalacia.

A study was made in Geneva of 44 patients with femoral neck fractures and no risk factor of osteomalacia to determine concentrations of 25OHD3, calcium, phosphorus, alkaline phosphatase, albumin, and globulins in blood. The results were compared with those obtained for control groups of adult and aged subjects, as well as of 21 subjects operated on for hip osteoarthritis. For the detection of occult osteomalacia, femoral head bone tissue from 14 patients with fractures was examined by histomorphometric methods. In more than a third of the cases, 25OHD3 and serum albumin values were lower than those found for adult and even aged control subjects. Some slight histological signs of osteomalacia were observed in 1 patient with a femoral neck fracture, but there was no correlation between the histologic and the blood data. In practice, when dealing with aged people with no obvious risk of osteomalacia, it is important that a systematic antiosteomalacia treatment consisting of large supplements of vitamin D be avoided and that the conditions of diet and living be carefully controlled.

Adult↗
PubMed1980

Carpal tunnel syndrome in chondrocalcinosis of the wrist. Clinical and histologic study.

Carpal tunnel syndrome (CTS) defined electromyographically was found in 8 of 22 unselected patients with chondrocalcinosis of the wrists (bilateral in 6, unilateral in 2). Thenar atrophy was the most frequently encountered clinical sign. In the hands with CTS, calcifications of the wrist were more extensive than in the hands, without CTS. Degenerative joint changes of the hands were significantly more frequent in the group suffering from CTS. Surgery was performed in 5 patients with CTS. Microscopic examination of the volar carpal ligament and the flexor synovial tendon sheath failed to reveal histologic signs of chondrocalcinosis. However, the presence of scarce crystals, as seen in polarized light as well as electron microscopy, suggests a minor form of chondrocalcinosis.

Adult↗
PubMed1980

Ultrastructural and cytochemical aspects of the initial phases of an experimental cutaneous calcinosis (calcergy) in the rat.

In rats a subcutaneous injection of KMnO4 leads to the calcification of the connective tissue. During mineral deposition, both intra- and extracellular changes are observed in the connective tissue. The intracellular phase is characterized by the formation of intramitochondrial granules and cytoplasmic vesicles, both in fibroblastic and extrinsic cells. In the extracellular phase, numerous heterogeneous matrix vesicles appear in the extracellular matrix. At the same time, globular particles which are resistant to microincineration, are observed between the collagen fibrils. The mineralization of the extracellular matrix takes place in two stages. The first stage comprises the appearance of needle-like structures and round aggregates. The needle-like structures are observed occasionally in the matrix vesicles and often in the extracellular matrix where they appear isolated or diverging from a central point. The round aggregates, composed of dense particles, are seen in the ground substance between the collagen fibrils. The second stage is characterized by a progressive mineralization of the collagen fibrils and the elastic fibers, without formation of extended calcified plaques.

Animals↗
PubMed1979

The mineralization processes in teleost fish scales.

In Teleost fish scales, growth and mineralization are continuous. Different mineralization processes can be distinguished. The external layer of the scale is the first to be mineralized and may be classified as the initial calcifying structure of the scale. The initial calcification loci are matrix vesicles of cellular origin always observed during the formation of this layer. This mineralization process takes place progressively, closely following the elaboration of the organic matrix in the scale periphery. The outer limiting and internal layers of the scale are developed after the external layer has been formed. A mineral substance is deposited without the mediation of matrix vesicles, but in contact with the previously mineralized external layer. This type of mineralization is called subsequential. However, the mineralization of the outer limiting layer closely follows the secretion of a collagen-free organic matrix and is thus different from the mineralization of the internal layer in which the calcification front remains remote from the collagen matrix surface and corresponds to a delayed mineralization process. The isolated calcifications (Mandl's corpuscles) which develop in the unmineralized laminae of the internal layer are mineralized in the absence of matrix vesicles and without making contact with a pre-existing calcified tissue, probably by a heterogeneous nucleation of the collagen fibrils.

Animals↗
PubMed1978

Mineral substance of bone tissue and of experimental cutaneous calcinosis in rats: chemical analysis and ESR study.

The evolution of the mineral constituents of subcutaneous calcinosis induced in rats by topical calciphylaxis was studied by the method of quantitative chemical analysis, and after treatment with excited gases by electron spin resonance (ESR) analysis. Chemical data show that the genesis of the subcutaneous calcinosis does not significantly alter the concentration of Ca, P, F, CO3, Mg, and Fe in the mineral phase of the femoral bone of calciphylactic rats. In the calcinosis an important increase of the fluoride concentration is noticed in function of the time after challenging. There is also a high concentration of Mg2+ ions in the early stages of the experimental calcification. Iron injected for the challenging is continuously present in the calciphylactic tissue after this treatment. This suggests that subcutaneous calcinosis might be a means of fixing certain heavy metal ions. After treatment with excited gases, the proportions of the trapped CO33- and O3- radicals are of the same order of magnitude in calciphylactic tissue after 12 days and observations in bone mineral. These suggest that after 12 days the mineral of the calciphylactic tissue has a crystalline state close to that of bone.

Animals↗
PubMed1978

Effects of hormones on osteocyte function and perilacunar wall structure.

Microradiographical and ultrastructural aspects of periosteocytic lacunae are determined by osteocytic activity, lacunar modeling and perilacunar miniremodeling in particular. The miniremodeling activity is constituted by two alternating processes: osteolysis and osteoplasis. Modifications of lacunar shape and size and of perilacunar wall ultrastructure, caused by a direct or indirect effect of certain hormones on osteocytic activity, were observed. The lacunar modeling alterations, particularly in cases of VDH or PTH deficiency, result in an irreversible impaired calcification of the lacunar walls and consequently, mottled lacunae. The alterations of periosteocytic osteolysis are characterized by an increase in number of enlarged lacunae and/or by increased magnitude of this lacunar enlargement. Usually observed as an effect of PTH and VDH, these alterations can also be induced by GC, T4, PG. On the other hand, CT causes a decrease in periosteocytic osteolysis. Periosteocytic osteoplasis is characterized by perilacunar bone formation of various aspects and is known to be stimulated by CT. The osteocytic response to hormones is a function of concentration and not of time; it is transient and not integrative. It can be concluded that none of the perilacunar wall modifications observed is characteristic of any particular hormonal effect or metabolic bone disease.

Calcitonin↗