Biomedical subjects

F Prudhommeaux

Publications and source records attributed to F Prudhommeaux.

7 recordsLinked to original sources

PubMed2002

Monosodium urate monohydrate crystal-induced inflammation in vivo: quantitative histomorphometric analysis of cellular events.

OBJECTIVE: To quantify the inflammatory cell response in rat air pouch pseudosynovial membrane during monosodium urate monohydrate (MSU) crystal-induced inflammation. METHODS: In the rat air-pouch model, we used a computer-assisted histomorphometric method to quantify cell distributions, based on cell linear densities, in histologic sections of membranes from pouches injected with MSU or saline. The volume, white blood cell (WBC) count, and histamine content of the pouch exudates were determined at several time points. RESULTS: Injection of 10 mg of MSU crystals into the pouch produced an acute exudate. After peaking at 24 hours, the exudate volume and WBC count decreased spontaneously over the next 3 days, simulating the self-limited course of acute gout. Membrane thickness followed a parallel course. Membrane polymorphonuclear cell (PMN) linear densities were closely correlated with exudate WBC counts, suggesting PMN recruitment from the subintimal synovial membrane. Both monocyte/macrophage and mast cell linear densities increased in the subintimal layer 2 hours after crystal injection (P = 0.038 and P = 0.03, respectively, versus controls), whereas PMN linear densities showed 2 peaks, one at 4 hours and the other 24 hours. The exudate histamine content peaked 6 hours after crystal injection, when mast cell linear densities were minimal in the membranes, suggesting mast cell degranulation. CONCLUSION: An increase in monocyte/macrophage and mast cell densities in the membrane preceded the PMN influx in the pouch membrane and exudate, suggesting that mast cells may be involved in the early phase of MSU crystal-induced inflammation, at least in this rat model.

Animals↗

PubMed2001

Comparative analysis of two different types of alumina-alumina hip prosthesis retrieved for aseptic loosening.

We compared and quantified the modes of failure and patterns of wear of 11 Mittelmeier and 11 Ceraver-Ostal retrieved alumina-alumina hip prostheses with reference to the corresponding clinical and radiological histories. Macroscopic wear was assessed using a three-dimensional co-ordinate measuring machine. Talysurf contacting profilometry was used to measure surface roughness on a microscopic scale and SEM to determine mechanisms of wear at the submicron level. The components were classified into one of three categories of wear: low (no visible/measurable wear), stripe (elliptical wear stripe on the heads and larger worn areas on the cups) and severe (macroscopic wear, large volumes of material lost). Overall, the volumetric wear of the alumina-alumina prostheses was substantially less than the widely used metal and ceramic-on-polyethylene combinations. By identifying and eliminating the factors which accelerate wear, it is expected that the lifetime of these devices can be further increased.

Adolescent↗

PubMed2000

Ceramic/ceramic total hip arthroplasty.

Alumina-on-alumina total hip arthroplasty has been used for 30 years, mainly in Europe. The theoretical advantages of this combination are represented by its remarkable sliding characteristics, its very low wear debris generation, and its sufficient fracture toughness. These advantages are achieved if the material is properly controlled with high density, high purity, and small grains. The authors summarize the results obtained with ceramic/ceramic total hip arthroplasty. Information is provided about in vivo behavior regarding wear debris characterization and quantification, and histological tissue examinations for inflammatory reactions, which were not encountered except when alumina debris was mixed with metal or cement. Modification of socket fixation resulted in improved clinical outcomes. With a press-fit metal shell and an alumina liner utilized for 10 years, the results are excellent especially in a young and active population. Alumina-on-alumina seems at the moment to be one of the best choices when a total hip arthroplasty has to be performed in young and active patients.

Aluminum Oxide↗

PubMed2000

Wear of alumina-on-alumina total hip arthroplasties at a mean 11-year followup.

The surface topography of 11 alumina-on-alumina hip arthroplasties retrieved for aseptic loosening at a mean 11-year followup was investigated. Macroscopic wear was assessed using a coordinate measuring machine. Microscopic wear features were evaluated by Talysurf analysis. Scanning electron microscopy was used to look at the alumina microstructure. Components were classified into three groups: (1) low wear with no sign of wear and average arithmetic roughness values below 0.05 microm; (2) stripe wear with a visible oblong worn area on the femoral heads and penetration rates below 10 microm/year; and (3) severe wear with a visible loss of material on both components, showing total roughness values as much as 4 microm and maximum penetrations higher than 150 microm. Alumina quality assessed by grain size measurements and porosity percentages improved progressively from 1977 to 1988. This resulted in a correlated decrease of the microscopic wear magnitude. However, on a macroscopic scale, factors responsible for either a load increase (weight, young age, and male gender) or impairment in the load distribution over the component surfaces (large grain size, nonoptimal initial cup inclination, and cup migration and/or tilting) increased the penetration rates.

Adolescent↗

PubMed1999

Effects of chitosan on rat knee cartilages.

The aim of this work is to study the effects of chitosan on rat knee cartilages. 0.2 ml of 0.1% chitosan solution pH = 6.9 were injected inside rat knees articular cavity. One, three and six weeks after injection, histological and histomorphometric studies were performed on undecalcified samples embedded in polymethylmetacrylate. Results show that after 1 and 6 weeks: (i) chitosan slows significantly (P < 0.005) the decrease in epiphyseal cartilage thicknesses and (ii) increases significantly articular cartilage chondrocyte densities (P < 0.002). However chitosan solution induces a proliferation of fibrous tissue with abundant fibroblasts, fibrocytes and monocytes inside the joint and this proliferation is still present after 6 weeks. This study suggests that chitosan could act on the growth of epiphyseal cartilage and wound healing of articular cartilage.

Animals↗

PubMed1996

Inhibition and prevention of monosodium urate monohydrate crystal-induced acute inflammation in vivo by transforming growth factor beta1.

OBJECTIVE: We investigated the effects of transforming growth factor beta 1 (TGF beta 1) on monosodium urate monohydrate (MSU) crystal-induced acute inflammation in vivo. METHODS: One hour after MSU crystal-induced acute inflammation was produced in the rat subcutaneous air pouch model, the effects of recombinant human TGF beta 1 (rHuTGF beta 1; 10-100 pg/animal) and ultrapure TGF beta 1 (UPTGF beta 1; 100 and 500 pg/animal) were assessed, based on absolute and differential white blood cell counts in the exudate. The effects of 10 pg of rHuTGF beta 1 preincubated with a specific anti-TGF beta antibody, and the effects of coinjection of crystals and rHuTGF beta 1, were also studied. RESULTS: UPTGF beta 1 and rHuTGF beta 1 markedly reduced MSU crystal-induced inflammation. Recombinant human TGF beta 1 also reduced inflammation when administered concomitantly with MSU crystals. Moreover, rHuTGF beta 1 and UPTGF beta 1, injected 1 hour after MSU crystal injection, reduced the inflammatory response in a dose-dependent manner. Injection of rHuTGF beta 1 (100 pg/animal) resulted in a > 90% reduction in the maximal white blood cell count, achieved 6 hours after crystal injection. Preincubation of rHuTGF beta 1 with a specific anti-TGF beta 1 antibody significantly (P < 0.01) reversed the inhibitory effect of rHuTGF beta 1 on the inflammatory response. Consistent with the regulation of inflammatory cell recruitment into the joint, the percentage of monocytes markedly decreased (P < 0.01) following local injection with rHuTGF beta 1 6 hours after MSU crystal injection. CONCLUSION: Exogenous TGF beta 1 prevents and inhibits MSU crystal-induced acute inflammation in vivo. Its role in the self-limitation of gouty attacks deserves consideration, among the various other factors involved.

Acute Disease↗

PubMed1996

Variation in the inflammatory properties of basic calcium phosphate crystals according to crystal type.

OBJECTIVE: To determine the inflammatory potential of basic calcium phosphate (BCP) crystals, which have been identified in human joints. METHODS: Hydroxyapatite, carbonate apatite, whitlockite, and octacalcium phosphate crystals were injected in rat air pouches. Volume and cellularity of the exudate were measured. Physicochemical properties of the injected BCP crystals were determined, and correlations with the magnitude of induced inflammatory responses were sought. RESULTS: Significant differences were observed among the volumes and white blood cell (WBC) counts of the pouch exudates, based on the various crystal types used to induce inflammation. A strong correlation was demonstrated between the specific surface (SS) area of the injected crystals and the area under the curve for induced WBC count versus time (R2 = 0.88, P = 0.05). This correlation was observed for SS area values below 50 m2/gm, but when SS area increased further, this parameter plateaued. Another parameter of inflammatory response was obtained by dividing the area under the curve figuring WBC counts versus time by the corresponding SS area for each crystal type. This parameter increased linearly with the Ca:P ratio (R2 = 0.97, P = 0.0003). CONCLUSION: The inflammatory potential of BCP crystals appeared to vary according to crystal features. SS area and the Ca:P ratio (which correlates with crystal solubility) influenced inflammatory properties. These results could explain the variable clinical consequences of BCP deposits, and must be taken into account in the choice of apatite ceramics for use as biomaterials.

Animals↗