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Biomedical subjects

G Riffat

Publications and source records attributed to G Riffat.

At least 37 records · Page 2Linked to original sources
PubMed1987

[Effects of weightlessness on osseous tissue of the rat after a space flight of 5 days (Cosmos 1514)].

Five pregnant female growing rats have been orbited for five days aboard the Cosmos 1514 soviet biological satellite. They were compared to five female rats kept in vivarium and five female conditioned rats in synchronised way. Histomorphometric studies were performed in order to investigate: 1. The early effects of weightlessness on the bone mass in loading (tibiae and femur) and unloading bones (thoracic and lumbar vertebrae). 2. The changes of osteoblastic and osteoclastic activities. A short exposure does not induce changes in the bone mass and the inner structure of loading and unloading bones. These results fit in well with human data available in the literature: they show that weightlessness doesn't change bone mass in the early phase of a spaceflight. However extrapolation of animal results to men is discussed. In unloading bones (vertebrae) osteoblastic activity was not measurable. Osteoclasts detected by histoenzymologic method don't change as far as their number per mm3 of trabecular bone is concerned. However the number per mm2 of trabecular area increases. It seems likely that an increase of the osteoclastic population occurs in trabecular bone. In loading bones, formation activity (appreciated by the measurement of osteoid seam thickness) and total osteoclastic resorption surfaces were not modified. These results are different from those of longer flights.

Animals↗
PubMed1987

[The bone in non-corticoid-treated sarcoidosis. A histomorphometric study].

The sarcoidosis granuloma secretes 1-25 dihydroxyvitamin D (1-25(OH)2 D) at the origin of the hypercalcemia found in about 20 p. cent of sarcoidoses. Its mechanism was considered exclusively of a digestive nature, but the activity of osteoclastic stimulation of 1-25(OH)2 D must consider an associated bony origin. Nine patients with bouts of non-steroid sarcoidosis were studied by osseous histomorphometric analysis. In a patient with hypercalcemia and radiographic manifestations, a high degree of bone remodelling is demonstrated, with stimulation of osteoclastic and osteoblastic activity. In eight patients with normocalcemia, two subgroups are individualized: two patients present intramedullary sarcoidosis granulomas with increased contact resorption; six patients present a normal marrow: the total areas of resorption remain increased. It is concluded that the activity of osteoclastic resorption is increased in sarcoidosis, which may explain partially the hypercalcemia. The absence of titration of 1-25(OH)2 D in our study does not permit to precise the role of this enzyme in the genesis of hyperosteoclastosis, although this seems quite plausible.

Adult↗
PubMed1986

Radionuclide bone imaging in diaphyseal aclasis with malignant change.

Chondrosarcoma is a rare complication in hereditary multiple exostoses. The six patients in this study have had a complete follow-up and constitute the largest group of such cases to have been studied so far. Five patients had histologic evidence of malignancy. Since histologic examination can be very difficult, any other diagnostic features, may it be clinical, radiologic, or scintigraphical, should be taken into account for early surgical treatment. Bone scintigraphic examination is a valuable adjunct to early diagnosis of malignant change by showing highest uptake in malignant areas. It is also very useful for posttherapeutic follow-up.

Adolescent↗
PubMed1986

[Effects of weightlessness on phosphorus and calcium metabolism and bone remodeling].

Weightlessness results in negative calcium balance which can only reflect a redistribution of calcium in the body: the loss of calcium in the faeces and/or urine is constant, but an increase in urinary hydroxyproline indicating bone collagen destruction is not always detectable; moreover, a slowing down of collagen maturation may be suspected. Bone analysis by histomorphometry in animals and by indirect, non-invasive methods in man shows a decrease in bone mass. However, this bone tissue atrophy might only reflect excessive ageing of the bone during weightlessness, as suggested by slow bone formation and lack of variation in bone resorption. Since the experimental results obtained in men and animals during simulated weightlessness on earth are not strictly identical with those observed in space- flights, their validity may be questioned. Additional studies (notably histomorphometric studies) are therefore required for a better knowledge, as well as prevention, of the problems raised by human life in space.

Animals↗
PubMed1986

Uncalcified cartilage resorption in human fetal cartilage canals.

In the human fetus, epiphyses appear as a solid avascular cartilaginous mass until the eleventh week of development. Around the third fetal month of development, vascular canals coming from the perichondrium are recognized in the mineralized epiphyseal cartilage. Whether cartilage canals develop by passive inclusion or active chondrolysis is still a matter of controversy. We studied the relationships between the intracanalar cells and the surrounding matrix on human fetal epiphyses embedded in glycol methacrylate. At the blind end of canals both stellate fibroblast-like cells and vacuolated macrophages are observed. These cellular foci show all characteristics of active chondrolysis (loss of metachromasia, lacunae containing cells intimately associated with matrix, and presence of granular debris). Similar resorptive foci have been observed in the pannus of rheumatoid joints and in the embryonic chick growth plate composed of uncalcified cartilage. A cellular cooperation (fibroblast/macrophage) is necessary for uncalcified cartilage breakdown. In the human fetus, monocytes/macrophages have been recognized in the peripheral blood as early as the twelfth week of gestation. Our observations support the view that chondrolysis due to both fibroblasts (of mesenchymal origin) and macrophages is the basic mechanism for cartilage canal development.

Abortion, Spontaneous↗
PubMed1986

Permanent preservation of whole alizarin red S skeletons by clearing and embedding in polyester resins.

A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method.

Anthraquinones↗
PubMed1984

Paget's disease of bone. A scanning electron microscopic study.

Paget's disease is a human bone dysplasia with a probable viral origin. SEM studies on anorganic and acid etched biopsies confirm the osteocondensation and the structural and textural abnormalities (presence of woven bone). Corrosion casts revealed a complex scaffolding structure of vascular channels. On resting fronts, the domains are small and irregular and surfaces are different from human fetal woven bone. Mineralizing fronts extend largely on bone surfaces and present evidence of abnormal thickness. Resorption surfaces extend irregularly in multiple directions and are often found unusually deep. Irregularity of osteoclastic lacunae was also evidenced. This SEM study suggests that an osteoblastic qualitative dysfunction could be associated with the osteoclastic changes.

Bone and Bones↗
PubMed1984

[Lumbar discal hernia after 65 years of age].

The authors make a retrospective study of a series of 200 patients who had been surgically treated, within a period of 26 months, for a lumbar discal pathology. Twenty of these (20%) were over 65 years old. A similar study was carried out in a rheumatological unit over a period of three years, and has included 266 patients, 21 of whom (7,8%) were older than 65. The comparison of both these series permits us to make some considerations concerning the frequency of this pathology after the age of 65, its clinical presentation and its treatment, which, as for the younger adult, must be surgical when the correct treatment fails and when a complication appears.

Aged↗
PubMed1983

Embedding iliac bone biopsies at low temperature using glycol and methyl methacrylates.

A mixture of pure and anhydrous glycol methacrylate and methyl methacrylate is used as an embedding medium for iliac bone biopsies. Infiltration is carried out at -20 C with the embedding medium and a cold inactivated catalyst-initiator system. Raising the temperature to 4 C initiates polymerization and limits the peak temperature of polymerization to 25 C. In this way, such thermolabile enzymes as osteoclastic acid phosphatase are preserved. After staining, sections are dehydrated in polyethylene glycol 400 30% in 2-propanol. This gives flat sections and improves staining properties.

Acrylates↗
PubMed1983

Histochemical identification of osteoclasts. Review of current methods and reappraisal of a simple procedure for routine diagnosis on undecalcified human iliac bone biopsies.

Osteoclasts are known to have a high acid phosphatase content. We have adapted the simple simultaneous mono-coupling azo-dye method of Grogg and Pearse to undecalcified bone sections. A cold embedding in a mixture of glycol and methyl methacrylate was shown to well preserve the enzyme activity. Sodium alpha-naphtyl phosphate (1 mg/ml) and fast violet B (2 mg/ml) are used in 0.1 M acetate buffer, pH 5.0. The addition of 1 mM L(+) sodium tartrate selectively inhibits the acid phosphoprotein phosphatase ("osteoblastic acid phosphatase") but not osteoclastic lysosomal acid phosphatase. Counterstaining with phosphomolybdic aniline blue WS leads to well contrasted sections, providing accurate measurements of osteoclast number.

Acid Phosphatase↗