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Biomedical subjects

P Deschamps

Publications and source records attributed to P Deschamps.

At least 19 recordsLinked to original sources
PubMed2000

Stimulation of osteoclast differentiation in vitro by mouse oncostatin M, leukaemia inhibitory factor, cardiotrophin-1 and interleukin 6: synergy with dexamethasone.

The role of oncostatin M in bone metabolism is not clearly defined, and the actions of mouse oncostatin M (mOSM) on osteoclast development has not been previously determined. We therefore examined the ability of recombinant mOSM to stimulate osteoclast formation and activity using cocultures of murine calvaria and bone marrow cells, and compared the responses to other members of the interleukin 6 family of cytokines including mouse leukaemia inhibitory factor (LIF), cardiotrophin-1 (CT-1) and IL-6. Mouse OSM, LIF and CT-1 strongly induced the formation of tartrate resistant acid phosphatase positive (TRAP(+)) multinucleated cells (MNC) in a dose-dependent fashion. OSM, LIF or CT-1 also elevated the number and size of resorptive pits when cocultures were added to smooth cortical bone slices, indicating enhancement of osteoclast activity. The activity of OSM was reduced by indomethacin (10(-8)-10(-6) M), whereas addition of dexamethasone (DEX) at 10(-7)-10(-5) M synergistically enhanced OSM-induced numbers of TRAP(+)MNC. DEX (10(-7) M) costimulation also synergistically enhanced TRAP(+)cell numbers of LIF, and CT-1 treated cocultures. IL-6 had no activity alone, but further enhanced TRAP(+)cell formation in mOSM or DEX (10(-7) M) treated cocultures. When added to mouse calvarial osteoblast cultures, mOSM induced secretion of IL-6 protein and elevation of mRNA whereas LIF or CT-1 did not. IL-6 mRNA levels and protein secretion were reduced in osteoblasts by costimulation with DEX. These results show that mouse OSM, LIF and CT-1 induce osteoclast differentiation and activation, that DEX synergizes with each in this activity, and that mouse OSM induces responses in osteoblasts that are not shown by LIF or CT-1. Collectively these data suggest an important role of these cytokines in osteoporosis caused by high levels of corticosteroid.

Animals↗
PubMed1997

[Physiopathology of bedsores].

Pressure is the primary pathogenic factor in the development of decubitus ulcers. Other major factors are shearing forces, friction and moisture. Significant intrinsic risk factors are immobility, age-related diseases, nutritional status, medications and smoking. The morbidity and mortality related to the complications of pressure sores are quite significant. Prevention is essential and is best achieved by identification of high risk patients. The therapeutic approach is based on the grade of pressure ulcer.

Age Factors↗
PubMed1996

Histomorphometric analysis of the effects of standard heparin on trabecular bone in vivo.

Long-term heparin treatment causes osteoporosis through an as yet undefined mechanism. To investigate this phenomenon, we treated rats with once daily subcutaneous injections of heparin (in doses ranging from 0.25 to 1.0 U/g) or saline for 8 to 32 days and monitored the effects on bone both histomorphometrically and by serial measurements of urinary type 1 collagen cross linked-pyridinoline (PYD) and serum alkaline phosphatase, markers of bone resorption and formation, respectively. Histomorphometric analysis of the distal third of the right femur in the region proximal to the epiphyseal growth plate showed that heparin induces both a time- and dose-dependent decreased in trabecular bone volume, with the majority of trabecular bone loss occurring within the first 8 days of treatment. Thus, heparin doses of 1.0 U/g/d resulted in a 32% loss of trabecular bone. Heparin-treated rats also showed a 37% decrease in osteoblast surface as well as a 75% decrease in osteoid surface. In contrast, heparin treatment had the opposite effect on osteoclast surface, which was 43% higher in heparin-treated rats, as compared with that in control rats. Biochemical markers of bone turnover showed that heparin treatment produced a dose-dependent decrease in serum alkaline phosphatase and a transient increase in urinary PYD, thus confirming the histomorphometric data. Based on these observations, we conclude that heparin decreases trabecular bone volume both by decreasing the rate of bone formation and increasing the rate of bone resorption.

Alkaline Phosphatase↗
PubMed1995

The effects of low molecular weight and standard heparin on calcium loss from fetal rat calvaria.

Osteoporosis is a well-recognized complication of long-term heparin use. However, the mechanisms by which heparin can influence bone metabolism are unclear. We report here that unfractionated heparin stimulates the process of bone resorption and that the low molecular weight heparins (LMWHs), enoxaparin, fragmin, logiparin, and ardeparin produce significantly less calcium loss than unfractionated heparin. To assess calcium loss from bone, we quantified the release of 45Ca into the culture medium of fetal rat calvaria. 45Ca release was increased in a dose-dependent manner by the addition of either unfractionated heparin or the LMWHs; but more than 50-fold higher LMWH concentrations were required to obtain an equivalent effect to unfractionated heparin. Thus, at concentration > or = 2 micrograms/mL (0.35 anti-Xa units/mL), unfractionated heparin stimulated 45Ca release 1.53 +/- 0.06 fold. 45Ca release was increased to a similar extent by the addition of either 10(-7) mol/L parathyroid hormone (PTH) or 10(-6) mol/L 1,25 dihydroxyvitamin D3 (1,25 Vit D3). In contrast to unfractionated heparin, LMWH concentrations > or = 100 micrograms/mL (> or = 14.0 anti-Xa units/mL) were required before maximum isotope release was observed. At concentrations well above therapeutic levels, the LMWHs stimulated 45Ca release by only 1.25 /+- 0.01-fold. Heparins with high and low antithrombin III affinities stimulated 45Ca release equally well. Both size and sulfation were found to be major determinants of heparin's ability to promote isotope release. Thus, the ability of defined heparin fragments to stimulate 45Ca release correlated with their molecular weight, and after N-desulfation the ability of heparin to induce isotope release was greatly diminished. Dermatan sulfate had no effect on 45Ca release. We conclude that size and sulfation are major determinants of heparin's ability to promote bone resorption and that the risk of heparin-induced osteoporosis may be reduced by the use of LMWH preparations.

Animals↗
PubMed1995

Adult onset Kawasaki disease diagnosed by the echocardiographic demonstration of coronary aneurysms.

A 17-year-old boy presented with fever, bilateral conjunctival infection, angina and extensive cervical adenopathy. Amoxycillin was started. Ten days later he was admitted to hospital because of persistent high fever, cervical adenopathy, erythema of the pharynx and tongue and lip fissuration. The most important interventions of his first hospitalization were endotracheal intubation because of increasing dyspnoea due to adult respiratory distress syndrome and haemodialysis for renal insufficiency. His admission to our hospital was marked by the echocardiographic discovery of giant coronary aneurysms in the first few centimeters of both right and left coronary arteries. Coronary angiography confirmed giant aneurysm formation of the right and left coronary arteries. Similarly, medium sized arteries (cerebral, hepatic, mesenteric, iliac) presented abnormalities and laboratory findings. This is the first description of adult-onset Kawasaki disease with giant coronary aneurysm formation and more generalized arterial involvement. The severity of the clinical symptoms and the severity of the coronary disease indicates that Kawasaki disease of the adult does not always have a benign course.

Adolescent↗
PubMed1992

REMEDHOS: the development of a medical and hospital liability database in Quebec.

Confronted in 1985 with the sudden rise of costs for liability protection, the health care sector in Canada took note of the fact that little or no reliable data were available and easily accessible to assess the actual scope and nature of the phenomenon of increasing medical liability suits in Canada. In order to correct this situation, a computerized database was created covering malpractice suits launched against Quebec health care professionals and establishments. This article presents the methodology that was used for the creation of the database; it describes the material that was used, the technical instruments that were developed and the software utilized. It also describes the structure and content of the database and presents its practical application with respect to the areas of risk management, health care evaluation, professional controls and tort reform.

Databases, Factual↗
PubMed1991

Resistance to photodynamic therapy in radiation induced fibrosarcoma-1 and Chinese hamster ovary-multi-drug resistant. Cells in vitro.

A degree of resistance to photodynamic therapy (PDT) has been induced in radiation-induced fibrosarcoma-1 (RIF-1) tumor cells by repeated photodynamic treatment with Photofrin (4 or 18 h incubation) in vitro to the 0.1-1% survival level, followed by regrowth from single surviving colonies. The resistance is shown as increased cell survival in the strain designated RIF-8A, compared to the wild-type RIF-1 cells, when exposed to increasing Photofrin concentration for 18 h incubation and fixed light exposure. No difference was found between RIF-1 and RIF-8A in the uptake of Photofrin per unit cell volume at 18 h incubation. Resistance to PDT was also observed in Chinese hamster ovary-multi-drug resistant (CHO-MDR) cells compared to the wild-type CHO cells, possibly associated with decreased cellular concentration of Photofrin in the former. By contrast, the PDT-resistant RIF-8A cells did not show any cross-resistance to Adriamycin, nor was there any significant drug concentration difference between RIF-1 and RIF-8A. These findings suggest that different mechanisms are responsible for PDT-induced resistance and multi-drug resistance.

Animals↗
PubMed1986

Keratoderma climactericum (Haxthausen's disease): clinical signs, laboratory findings and etretinate treatment in 10 patients.

10 cases of keratoderma climactericum are reported. This keratosis of the palms and soles appears late in women of menopausal age. The keratotic lesions first develop at the plantar pressure points, making walking troublesome. Involvement of the hands remains discrete. Examination for contact allergy, fungal tests, vitamin A serum levels, and sex hormones were negative or normal in all the 10 patients. Microscopy revealed a lichenified eczema with evidence of mechanical irritation. Etretinate (0.78 mg/kg/day) brought about partial or total remission of the hyperkeratosis. Pain on walking disappeared in all the patients.

Aged↗
PubMed1986

[Interaction between asthma and maxillary sinusitis].

We have studied atopic status and respiratory function in 69 asthmatics in relation to possible radiological changes in the sinuses. These alterations were classified under four headings: normal, mucosal thickening (greater than 3 mm), polyp or opaque films. The bronchial obstruction, evaluated by FEV1/FVC ratio was compared in the 4 groups. The reversibility of airflow obstruction by beta-2-sympathomimetics (Fenoterol) was the same with or without changes in the sinuses. The atopic trait (RAST or immediate prick tests) or non-atopic asthma was not associated with any sinus abnormalities. In conclusion, if a close association between asthma and radiological disease of the sinuses exists (60% of cases), it does not seem that chronic sinusitis worsens bronchial obstruction or reduces sensitivity to beta-2-sympathomimetics. The changes in the sinus mucosa may be induced by the same aetiologic agent (allergic or non allergic) as asthma.

Adult↗
PubMed1985

An example of interaction between environmental pollutants: modification of thiram toxicity to freshwater organisms by nitrites or nitrates in relation to nitrosamine synthesis.

Thiram, a dithiocarbamate fungicide, is known to evolve to dimethylnitrosamine (DMNA) when associated with nitrites. Conditions of appearance of that carcinogenic compound have been studied in short-term experiments by association of the fungicide, nitrates or nitrites, and species representative of freshwater biota. DMNA has been estimated by GLC equipped with a specific detector. Chlorella vulgaris can rapidly produce nitrites from nitrates and DMNA is obtained in presence of thiram. Daphnia magna can also synthesize DMNA but nitrites have to be added to the medium. Increased toxicity of thiram is observed. The same results are obtained on Cyprinus carpio and for a part on Brachydanio rerio. When the species are associated in a 15-day experimental food chain, and intoxicated algae feed the two other levels, no significant transfer is observed. Nevertheless, some DMNA hazard may exist for particular species exposed to thiram associated with nitrites or even nitrates if algae are present.

Animals↗
PubMed1985

[Neuropathies caused by thalidomide].

Symptoms and signs in four patients with thalidomide-induced neuropathy developing during treatment of discoid lupus were limited for long period to distal paresthesiae with altered sensory conduction velocities. Semi-thin biopsy specimens of the distal sural nerve showed depopulation of myelinized fibers, mainly affecting those of large caliber, and signs of axonal degeneration. Study of dissociated fibers showed a high proportion of E fibers. Morphometry confirmed the axonal lesion. Ultrastructural examination demonstrated anomalies of axons of amyelinic fibers (vacuoles, lamellar figures) and of Schwann cells (stacked cytoplasmic prolongations), together with numerous collagen pockets, all non-specific lesions. The disease course was slow, with disappearance of sensory symptoms in a few weeks in 3 of the 4 cases and normal clinical findings in one of the four patients one year after cessation of treatment. Definite correlations between the dose administered and the severity of the neuropathy could not be established. The still poorly understood mechanism of action is discussed.

Acute Disease↗