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J Dequeker

Publications and source records attributed to J Dequeker.

At least 145 records · Page 8Linked to original sources
PubMed1995

The European Spine Phantom--a tool for standardization and quality control in spinal bone mineral measurements by DXA and QCT.

The lack of standardization in bone mineral measurements of the lumbar spine and other skeletal sites is generally recognized as an important and unresolved issue. We report and discuss efforts at standardization and cross-calibration of DXA and QCT equipment. We have designed and tested a geometrically defined, semi-anthropomorphic phantom, the European Spine Phantom (ESP). It contains a spine insert consisting of three vertebrae of increasing bone mineral densities and thicknesses of cortical structures; the respective parameters are given in tabular form for the final phantom design. Results for cross-calibration with the ESP compare well with patient results. Measurements on the first 30 phantoms confirmed that the ESP can be manufactured with a variation of about 1%. We conclude that the ESP is suitable for daily quality assurance, cross-calibration of instruments and universal standardization. The ESP was used to establish standardized BMD (sBMD) units for DXA equipment going into effect in late 1995. Its acceptance by manufacturers as a calibration standard for DXA and QCT measurements appears imminent.

Absorptiometry, Photon↗
PubMed1995

Mineral density quantitation of the human cortical iliac crest by backscattered electron image analysis: variations with age, sex, and degree of osteoarthritis.

Bone samples from the rim of the iliac crest were obtained at autopsy from 59 patients aged 23 to 75 years, of whom 10 men and 10 women aged 50-75 years had osteoarthritis diagnosed by hand X-rays. An equal number in the same age group and 10 men and 9 women aged less than 50 years were without osteoarthritis. After embedding the bone in PMMA, the blocks were cut, polished, and coated with carbon. The fractions of bone falling within four consecutive bands of signal level were derived from digital backscattered electron imaging. Normal males had more low and medium density bone and normal females more very high density phase tissue proportionately. In both male and female osteoarthritis cases, low and medium fractions were low. The very high density fraction was mainly calcified fibrocartilage; when it was excluded from the calculations, the low, medium, and high phases occurred equally in normal males but increased stepwise in normal females and in osteoarthritis cases of both sexes. The results suggest a lower rate of bone renewal in females than males, and in male osteoarthritis subjects than normal males. An increased proportion of bone of high density would reduce the quality of the bone by increasing its stiffness.

Adult↗
PubMed1995

Dual X-ray absorptiometry--cross-calibration and normative reference ranges for the spine: results of a European Community Concerted Action.

Bone density measurements by dual X-ray absorptiometry (DXA) of the spine can now be made precisely, but there is no uniformity in reporting results and in presenting reference data. A European Union Concerted Action therefore devised a uniform procedure for cross-calibrating and standardizing instruments, using the European spine phantom (ESP) prototype. This phantom differs in a number of respects from the final version of the ESP. Eighteen centers in nine countries obtained 1619 records (1035 women) from Caucasian subjects, aged 20-80 years, drawn from normal populations. The DXA machines used were made by the Hologic, Lunar, and Norland companies. Highly statistically significant differences were evident between populations, both in apparent rates of bone loss with age and in the spread of values about the age-adjusted means. There were small residual differences in the results obtained with the three machine brands which could have been due to the relatively large between-center population differences we observed. The alternative or additional explanation that they were attributable, in part, to the design differences between the ESP prototype and the definitive ESP, which became available after this study was completed, was shown to be a valid possibility. Results from postmenopausal women reported in relation to the years that have elapsed since menopause showed reduced population variance when compared with conventional reporting in relation to age. After cross-calibration, the center with the highest age-adjusted normal density value averaged 23% more than the center with the lowest. It is therefore crucially important to select appropriate reference data in clinical and epidemiological studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1995

Steroid myopathy induced by epidural triamcinolone injection.

Epidural steroid injections are widely used for the treatment of lumbago and sciatica although their efficacy has not yet been demonstrated in a convincing way. Moreover, systemic complications, although rare, have been documented. The present case report illustrates that even a single low-dose epidural injection may induce Cushing's syndrome and even steroid myopathy.

Aged↗
PubMed1995

Bone density and osteoarthritis.

Osteoarthritis (OA) is a physiologic imbalance, a "joint failure" similar to "heart failure" in which mechanical as well as constitutional factors play a role. The initiation and progression of cartilage damage are distinct phenomena. One of the mechanisms of initiation of OA is subchondral bone stiffness, often a part of generalized inherited increased bone density. Evidence is accumulating that primary OA might initially be a bone disease rather than a cartilage disease. OA cases have a better preserved bone mass, even independent of body weight. Studies on iliac crest bone, a site far from load bearing forces, have shown differences in bone mass, biomechanical characteristics, biochemical composition, and mineralization profile according to the presence of OA in the hands. Women with OA had significantly more bone and the bone was significantly stiffer, they had higher compressive strength, higher osteocalcin, higher insulin-like growth factor I and II and transforming growth factor beta content, and a mineralization profile shifting to higher densities. These quantitative and qualitative differences in bone may produce disease by increasing subchondral bone stiffness and by making subchondral bone less deformable to impact leads. This stiff bone transmits more force to overlying cartilage, making it more vulnerable.

Bone Density↗
PubMed1994

Long-term effect of omega-3 fatty acid supplementation in active rheumatoid arthritis. A 12-month, double-blind, controlled study.

OBJECTIVE: To study the long-term effects of supplementation with omega-3 fatty acids (omega 3) in patients with active rheumatoid arthritis. METHODS: Ninety patients were enrolled in a 12-month, double-blind, randomized study comparing daily supplementations with either 2.6 gm of omega 3, or 1.3 gm of omega 3 + 3 gm of olive oil, or 6 gm of olive oil. RESULTS: Significant improvement in the patient's global evaluation and in the physician's assessment of pain was observed only in those taking 2.6 gm/day of omega 3. The proportions of patients who improved and of those who were able to reduce their concomitant antirheumatic medications were significantly greater with 2.6 gm/day of omega 3. CONCLUSION: Daily supplementation with 2.6 gm of omega 3 results in significant clinical benefit and may reduce the need for concomitant antirheumatic medication.

Anti-Inflammatory Agents↗
PubMed1994

Effect of 1 alpha-vitamin D3 on bone strength and composition in growing rats with and without corticosteroid treatment.

The effects of 1 alpha-vitamin D3 were studied for 6 months in 2-month-old male and female rats on a moderately low calcium diet with or without low-dose prednisolone treatment. Both cortical bone mechanical and biochemical properties were examined. Femoral bone specimens were subjected to torsional loading tests. With age, bone strength and stiffness increased in both sexes, accompanied by an increased degree of mineralization (bone ash and calcium concentrations). During growth, strength and stiffness increased more in male than in female rats. When 1 alpha-vitamin D3 (0.5 micrograms/kg/day) was given alone, bone mechanical competence improved significantly whereas insulin-like growth factor-I (IGF-I) and calcium concentrations in the bone matrix were significantly reduced. Treatment with low-dose prednisolone (0.5 mg/kg/day) alone did not influence bone mechanical properties compared with intact control rats (without prednisolone) although a significant reduction in calcium concentration and an increased phosphorus concentration were measured. A combined therapy with prednisolone and 1 alpha-vitamin D3 significantly increased bone strength, toughness, and stiffness compared with control bones. Both mineralization degree (ash and calcium concentration) and IGF-I concentration were decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The variable incidence of hip fracture in southern Europe: the MEDOS Study.

We assessed the incidence of hip fracture and ecological correlates in residents of 14 communities in six countries of Southern Europe. Hip fracture cases were recorded prospectively in defined catchment areas over a 1-year interval. A retrospective questionnaire was used to assess ecological differences between communities. During a 1-year period of observation a total of 3629 men and women over the age of 50 years were identified with hip fracture from a catchment of 3 million. In all communities the fracture rate increased exponentially with age. There were large and significant differences between centres in the doubling time for hip fracture risk with age and in crude and age-standardized rates. Greater than 4-fold and 13-fold differences in age-standardized risk were found amongst men and women respectively. The lowest rates were observed from Turkey and the highest from Seville, Crete and Porto. Fractures were significantly more frequent among women than men with the exception of three rural Turkish centres. Indeed, in rural Turkey the normal female/male ratio was reserved. Variations in incidence between regions were greater than the differences within centres between sexes, and there was a close and significant correlation between incidence rates for men and those for women in the regions studied. Excess female morbidity increased progressively from the age of 50 years but attained a plateau after the age of 80 years, suggesting a finite duration of the effect of the menopause. The retrospective questionnaire completed by 80% of cases suggested that differences in incidence between the communities studied could not be explained by differences in gonadal status in women. In both men and women cross-cultural associations were found with factors related to age or socioeconomic prosperity, the majority of which disappeared after adjustment for age. We conclude that there are marked and sizeable differences in the incidence rates of hip fracture throughout Southern Europe. The reasons for these differences are not known but affect both men and women, and are likely to be related to lifestyle or genetic factors rather than to differences in endocrine status.

Age Factors↗
PubMed1994

Total body mineral mass measured with dual photon absorptiometry in healthy children.

Using dual photon absorptiometry, bone mineral content (BMC) and bone mineral density (BMD) of the total body and the lumbar spine were assessed in 97 healthy, Caucasian children aged 3-14 years. Excellent correlations were found between BMC and BMD on the one hand and age, body height and body weight on the other. No differences were found between boys and girls. There was a strong correlation between lumbar spine measurement as compared to those of the total body. Regression equations for total body and the different parts of the skeleton were calculated with either BMC or BMD as the dependent variable, and age, body height and body weight as independent variables. High variation coefficients were obtained in these multiple regressions, except for the head. For total body BMC and total body BMD, growth charts were constructed using Tanner and Whitehouse data on body height and body height and body weight. Conclusions. The increase in total body mineral content is an important feature of normal growth. Normal data for BMC and BMD in childhood are essential for bone mineralisation abnormalities in paediatric patients.

Absorptiometry, Photon↗
PubMed1994

A high dose (up to 200 mg) tolerance and efficacy study of intra-articular rimexolone (Org 6216) in rheumatoid synovitis of the knee.

Twenty patients with classical or definite rheumatoid arthritis received one intra-articular injection of 40, 80, 120, 160 or 200 mg rimexolone (Org 6216) into one knee joint. Rimexolone was well tolerated and the incidence of side-effects was low. A beneficial effect was sustained over the study period of 94 days and a long-lasting effect was observed in 84% of the patients after one year and in 79% after 2 years. Safety parameters remained unaffected. Individual changes in adrenal response to ACTH and morning cortisol levels did not correlate with the dose or with serum levels of rimexolone. Rimexolone showed linear kinetics. The mean residence time in the intra-articular depot was 44 days (SD +/- 53) with a median of 26 days. Ninety percent was absorbed after 4 months. Outside the intra-articular depot the mean residence time was less than 0.1 days.

Adrenocorticotropic Hormone↗
PubMed1994

Cauda equina syndrome complicating ankylosing spondylitis: role of computed tomography and magnetic resonance imaging.

We present two cases of cauda equina syndrome in ankylosing spondylitis. Cauda equina syndrome is a rare complication of ankylosing spondylitis, the pathogenesis of which is not well understood. The onset is insidious with pain and sensory symptoms; sphincter disturbances are common. After a period of increasing neurological symptoms, the condition tends to stabilize. The degree of nerve involvement is variable and can be accurately defined by electromyography. The diagnosis has to be confirmed by computed tomography (CT) or magnetic resonance imaging (MRI); myelography must be avoided. There is no specific treatment, except for pain control. The different clinical presentations and the role of new imaging techniques, CT and MRI, are demonstrated.

Cauda Equina↗
PubMed1994

European semi-anthropomorphic phantom for the cross-calibration of peripheral bone densitometers: assessment of precision accuracy and stability.

A semi-anthropomorphic 'distal radius like' phantom, developed by Kalender and Ruegsegger for use in peripheral bone densitometry using single photon (DPA) dual X-ray (DXA) and quantitative computed tomography (QCT) machines, has been studied with a view to cross-calibrating different types and brands of densitometers in current use. In the context of an EU 'Concerted Action' (second Framework Programme) the phantom was repeatedly measured on six SPA machines, three DXA machines and nine QCT machines (545 measurements). Linear regression equations were derived, individual to each machine, which allowed the derivation of 'standardized densities'. In this way we converted measurements made by machines of the same modality to a common scale of measurements. Two machines (one DXA, one SPA) showed statistically significant instability over time emphasising the need for rigorous quality control in the application of densitometry. In other respects these results provide an encouraging basis for the derivation of standardized normative ranges and the more effective use of peripheral densitometry in future clinical and epidemiological studies.

Absorptiometry, Photon↗