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Biomedical subjects

C A Baud

Publications and source records attributed to C A Baud.

16 recordsLinked to original sources
PubMed1991

Structural changes of the periosteocytic area in Vipera aspis (L.) (Ophidia, Viperidae) bone tissue in various physiological conditions.

Microradiographs of ribs and vertebrae of the snake Vipera aspis, over an annual cycle, show a significant enlargement of the osteocytic lacunae in the winter months and, for the breeding females, during the period of embryo development. This enlargement is due to resorption of bone substance (periosteocytic osteolysis). The objection that such morphological findings could as well be explained by the formation of new, larger osteocytes derived from recent osteoblasts does not apply to the present animal model. No internal bone remodelling occurs during the annual seasonal cycle and therefore no new osteoblasts would have differentiated to osteocytes in the interior of the bone. In the vertebrae, an additional process is indicated as an area of decreased mineral density, termed demineralization halo, around the periosteocytic lacunae. An electron microscopy study suggests that this process of demineralization is not the first stage of periosteocytic resorption, but an additional process of demineralization. Thus, both osteolysis and demineralization halos in the perilacunar osteocytic region of the bone tissue represent reversible biological processes mediated by the osteocytes.

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

Paramagnetic and crystallographic effects of low temperature ashing on human bone and tooth enamel.

Low temperature ashing by excited gas (LTA) causes crystallographic and paramagnetic alterations of the human bone and tooth enamel mineral. On the one hand, LTA induces variations of the alpha lattice parameter. These variations depend upon the nature of the gas used, but are little affected by its degree of excitation. Trapping of gas molecules in the crystal structure is demonstrated. On the other hand, LTA produces two preponderant paramagnetic centers in bone and enamel samples at 20 degrees C. Their inorganic origin clearly indicated. One of the two radicals has been identified as O3- (g1 = 2.002, g2 = 2.010, g3 = 2.016) and the other as (CO3-3 (parallel = 1.996, g = perpendicular 2.003). Variations of the alpha lattice parameter and trapping of paramagnetic gas species do not seem to be directly related.

Apatites↗
PubMed1978

Diffuse enthesopathic hyperostosis--anatomical and radiological study on a macerated skeleton.

Anatomico-radiological study of a macerated skeleton in a 43-year-old diabetic woman. An important spondylosis with hyperostosis of the cervical, thoracic and lumbar vertebrae was seen. There were associated changes of insertional hyperostosis at various levels, particularly at the iliac crests. Paget's disease of the left iliac crest was also noted in the corresponding hyperostosis. This case presentation offers an opportunity to discuss local mechanical factors (observed at the tendinous insertions) as well as generalized considerations on the "terrain" of diabetes and perhaps malnutrition. It also demonstrates the interest that an anatomico-radiological comparison on macerated specimens can have for certain osteoarticular research, teaching and paleopathology.

Adult↗
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↗
PubMed1977

Tendon calcifications in chondrocalcinosis. A clinical, radiologic, histologic, and crystallographic study.

Fine linear extraarticular calcium deposits were found in X-rays of 7 of 52 patients with articular chondrocalcinosis (ACC). Seven Achilles tendons, seven quadriceps tendons, and one plantar fascia were affected. In a control group of comparable age and sex, without ACC but with generalized osteoarthritis, no calcifications were found in the tendons. On a biopsy specimen of Achilles tendon with such calcium deposits, X-ray diffraction showed that they had the characteristics of calcium pyrophosphate dilhydrate. Isolated small foci of crystals were observed on some segments of tendon bundles. The presence of fine linear calcifications on X-rays of the Achilles or quadriceps tendons may be a useful aid in the radiologic diagnosis of so-called articular chondrocalcinosis.

Achilles Tendon↗
PubMed1977

Minor elements in bone mineral and their effects on its solubility.

Mineral substance deposited in bone tissue when either strontium or fluoride are present, is both qualitatively and quantitatively different from that deposited in their absence. The presence of these ions causes not only heteroíonic substitutions in the crystalline lattice of the apatite phase, but also important modifications of the percentage of crystalline mineral, of crystal size and perfection, and of quantity of mineral per unit volume. These modifications affect the in vitro and in vivo demineralization of bone tissue.

Animals↗
PubMed1976

[Industrial fluorosis].

43 potroom workers (aluminium industry) with fluorosis have been compared with 18 foundry workers of the same age, but who had never been exposed to fluorides. Clinical examination revealed a higher incidence of articular pain and limitation of motion in the exposed group. The diagnosis of fluorosis is not only clinical but calls for other investigations such as urinary fluoride determination, bone radiology and, above all, bone biopsy for fluoride determination, histology and microradiography.

Aged↗
PubMed1976

[Biophysical and ultrastructural aspects of an implant-bone interface].

The study of the interface between implant and bone suggests that the ideal material should not be chosen the most inert, but on the contrary among materials apt to provoke the formation of a connective layer between bone and implant. Certain ceramic materials have these required properties.

Animals↗
PubMed1976

[Anatomopathology of Paget's disease. Combined approach by conventional methods and ultrastructural study].

Paget's disease is manifested by bone remodelling where the rate of the resorption-osteogenesis pattern is abnormally enhanced. This leads to the formation of a pathologically structured bone. The bone remodelling does not concern the entire skeletal structure and is unequally active. It is limited by the neighbouring healthy bone in which it can spread out. It can be followed by the development of a sarcoma. When the acetabulum or the femoral head are affected this can occasionally, lead to a coxopathy with cartilage deterioration. An anatomo-pathological study of Paget's disease is necessary for understanding the basis and the limits of biopsy diagnosis as well as its various manifestations (clinical, radiological, biological, scintigraphical, thermographical). This study also serves as a basic for pathogenic discussion.

Aged↗