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J-M Kaufman

Publications and source records attributed to J-M Kaufman.

6 recordsLinked to original sources
PubMed2007

Complex segregation analysis accounting for GxE of bone mineral density in European pedigrees selected through a male proband with low BMD.

Osteoporosis is a common multifactorial disorder characterized by low bone mass (BMD) and high susceptibility to low-trauma fractures. Family and twin studies have found a strong genetic component in the determination of BMD, but the mode of inheritance of this trait is not yet fully understood. BMD is a complex trait whose expression is confounded by environmental influences and polygenic inheritance. Detection of potential gene-environment interactions is of great interest in the determination of bone health status. Here we have conducted segregation analyses, using the regressive class D models, in a sample of 100 European pedigrees (NEMO) with 713 subjects (524 measured for phenotypes) identified via a male with low BMD values at either the Lumbar Spine or the Femoral Neck. Segregation analyses were conducted on the residuals of LS-BMD and FN-BMD adjusted for gender, age and BMI. We tested for gene-covariate (GxE) interactions, and investigated the impact of significant GxE interactions on segregation results. Without GxE a major effect was found to be marginally significant in LS-BMD and highly significant in FN-BMD. For both traits the Mendelian hypothesis was rejected. Significant Age x gene and BMI x gene interactions were revealed. Accounting for GxE increased statistical evidence for a major factor in LS-BMD, and improved the fit of the data to the Mendelian transmission model for both traits. The best fitting models suggested a codominant major gene accounting for 45% (LS-BMD) and 44% (FN-BMD) of the adjusted BMDs. However, substantial residual correlations were also found, and these remained highly significant after accounting for the major gene.

Adult↗
PubMed2004

Teriparatide effects on vertebral fractures and bone mineral density in men with osteoporosis: treatment and discontinuation of therapy.

Teriparatide (rhPTH[1-34]), a bone-forming agent for the treatment of osteoporosis, increases bone mineral density in men and women, and reduces the risk of fractures in women with osteoporosis. However, fracture efficacy has not yet been confirmed in men. Further, there is limited information on the effect of withdrawal of teriparatide. The purpose of this manuscript is to report on bone mineral density and vertebral fracture incidence during a 42-month observation period, from the baseline of the previously reported treatment study in men [1] through 30 months of posttreatment follow-up. Three hundred fifty-five men who were treated with once-daily self-injections of either placebo or 20 or 40 microg of teriparatide participated in the follow-up study. Bone mineral density gradually decreased following discontinuation of teriparatide therapy. However, the lumbar spine and total hip values remained significantly higher than baseline after 30 months of follow-up (p< or =0.001). Antiresorptive treatment prevented the decline and tended to further increase bone mineral density. Lateral thoracic lumbar radiographs obtained at baseline and 18 months after discontinuation of teriparatide were available for 279 men. Of these men, 11.7% assigned to placebo, 5.4% treated with teriparatide 20 microg, and 6.0% treated with teriparatide 40 microg had an incident vertebral fracture. In the combined teriparatide treated groups vs placebo, the risk of vertebral fracture was reduced 51% (nonsignificant, p=0.07). The incidence of moderate or severe fractures was significantly reduced by 83% (p=0.01). In conclusion, men who received teriparatide and who may have received follow-up antiresorptive therapy had a decreased risk of moderate and severe vertebral fractures.

Adult↗
PubMed2003

Patient assessment using standardized bone mineral density values and a national reference database: implementing uniform thresholds for the reimbursement of osteoporosis treatments in Belgium.

Dual-energy X-ray absorptiometry (DXA) devices from the three main manufacturers provide different bone mineral density (BMD) values, due in part to technical differences in the algorithms for bone mineral content (BMC) and area measurements and in part to the use of different manufacturer-derived reference databases. As a result, significant differences exist between Hologic, Lunar and Norland systems in the reported young normal standard deviation scores or T-scores. In a number of European countries, including Belgium, a T-score below -2.5 is one of the key criteria for reimbursement of osteoporosis treatments. This paper addresses the first attempt to implement a nationwide, uniform expression of BMD in patients, in order to harmonize drug reimbursement. To this end, measures were taken to implement a uniform expression of BMD in Belgian patients, by converting each manufacturer's absolute BMD to standardized BMD (sBMD) values and by establishing a single national reference range.

Absorptiometry, Photon↗
PubMed2003

Stimulation of luteinizing hormone secretion by N-methyl-D,L-aspartic acid in the adult male guinea-pig: incomplete blockade by gonadotropin-releasing hormone receptor antagonism.

Stimulation of luteinizing hormone (LH) secretion by N-methyl-D,L-aspartic acid (NMA), reported for several mammalian species, is generally accepted to be mediated through stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) release. In view of a previously reported unexpected inhibitory action of NMA on GnRH release from hypothalamic explant of intact male guinea-pigs, the aim of the present study was to assess the in vivo effects of NMA in the adult male guinea-pig. In the gonadally intact male, NMA (5 mg/animal) elicited a robust LH secretion, which was blocked by the N-methyl-D-asparte-receptor antagonist DL-2-amino-5-phosphonovaleric acid (AP-5,12 mg/animal). In the castrated male, NMA elicited only a marginal and inconsistent LH secretion. Cetrorelix (CET), a GnRH receptor antagonist, administered intracardiacally 1 min or 45 min preceding bolus injection of NMA significantly reduced the LH response to NMA in the intact male. Surprisingly, following GnRH receptor blockade with CET, there still was a substantial residual serum LH response to NMA, while CET completely abolished the serum LH response to high dose (1 microg or 10 microg) guinea-pig GnRH (gpGnRH). These results indicate that NMA stimulates LH secretion in the gonadally intact male guinea-pig in vivo and that this effect is mediated in part through gpGnRH-independent mechanisms.

Animals↗
PubMed2003

[Osteoporosis in the elderly man].

Elderly men are at substantial risk for fracture. Morbidity after osteoporotic fractures appears to be more serious and mortality more common in men than in women. Risk factors for osteoporotic fractures in men appear to be qualitatively similar to those in women. Low bone mineral density (BMD) is an important risk factor for fracture in men; however, further clarification of the relationship between BMD, bone geometry and fracture risk is needed. Our understanding of the mechanisms underlying senile bone loss and the pathogenesis of senile osteoporosis in men remains fragmentary with, in particular, the need for further clarification regarding the precise impact of hormonal status in elderly men on skeletal homeostasis. Nevertheless, the available evidence indicates a role for both testosterone and estrogens in the regulation of bone metabolism in elderly men. Recommendations concerning prevention and treatment of senile osteoporosis in men should focus on the minimization of known risk factors for bone loss and falls. Testosterone treatment may be useful only in those men with initially low serum testosterone. As to other pharmacological treatment modalities, prospective trials specifically in elderly men, and preferably with fracture incidence as the primary clinical endpoint, are required.

Adult↗