The aim of the study was to compare the bone mineral density (BMD) and body composition between ambulatory male MS patients and control subjects and to evaluate the relationships among body composition, motor disability, glucocorticoids (GC) use, and bone health. Body composition and BMD were measured by dual-energy X-ray absorptiometry in 104 ambulatory men with MS (mean age: 45.2 years) chronically treated with low-dose GC and in 54 healthy age-matched men. Compared to age-matched controls, MS patients had a significantly lower total body bone mineral content (TBBMC) and BMD at all measured sites except for the radius. Sixty five male MS patients (62.5 %) met the criteria for osteopenia and twenty six of them (25 %) for osteoporosis. The multivariate analysis showed a consistent dependence of bone measures (except whole body BMD) on BMI. The total leg lean mass % was as an independent predictor of TBBMC. The Expanded Disability Status Scale (EDSS), cumulative GC dose and age were independent determinants for BMD of the proximal femur. We conclude that decreasing mobility in male MS patients is associated with an increasing degree of osteoporosis and muscle wasting in the lower extremities. The chronic low-dose GC treatment further contributes to bone loss., V. Zikán ... [et al.]., and Obsahuje seznam literatury
The peak bone mass and the rate of bone loss are in part genetically determined. It has been suggested that bone mineral density (BMD) may be related to allelic variation in the apolipoprotein E (ApoE) gene locus. ApoE is important in the receptor-mediated clearance of chylomicron particles from the plasma, Apo E4 having the highest and Apo E2 the lowest receptor affinity. Chylomicrons are the main carrier of vitamin K in the plasma; vitamin K plays an important role in the carboxylation of osteocalcin. We have tested the hypothesis that persons with E4 variant would have lower BMD and increased bone turnover than those with E2 variant. A total of 18 ApoE 2/2 and ApoE 4/4 homozygotes were selected from 873 patients who were examined for the ApoE genotype. BMD in lumbar vertebral, femoral neck and distal forearm was measured and plasma concentrations of osteocalcin and C-terminal fragments of collagen (CTx) were determined. BMD values (expressed as T-score) at the three specified sites were -0.12± 1.72, -0.52± 1.32 and -0.52± 0.81 in ApoE 2/2 group and -0.24± 1.22, 0.00± 0.84 and -0.17± 1.07 in the ApoE 4/4 group. Plasma osteocalcin and CTx were within normal limits in both groups. In conclusion, we did not observe any association of ApoE genotype with BMD and biochemical markers of bone metabolism in ApoE 2/2 and ApoE 4/4 homozygotes., T. Štulc, R. Češka, A. Hořínek, J. Štěpán., and Obsahuje bibliografii
Bone remodeling is a tightly coupled process consisting of repetitive cycles of bone resorption and formation. Both processes are governed by mechanical signals, which operate in conjunction with local and systemic factors in a discrete anatomic structure designated a basic multicellular unit (BMU). The microenvironment around total joint arthroplasty is a dynamic and complex milieu influenced by the chemical and physical stimuli associated with servicing the prosthesis. A key factor limiting the longevity of the prosthesis is polyethylene wear, which induces particle disease, and this may lead to increased and prolonged activity of BMUs resulting in periprosthetic osteolysis. Several pathways regulating BMU function have been reported in the past, including RANKL/RANK/OPG/TRAF6, TNF-α/TNFR/TRAF1, and IL-6/CD126/JAK/STAT. Moreover, the expression and functional activity of all these molecules can be affected by variations in their genes. These may explain the differences in severity of bone defects or prosthetic failure between patients with similar wear rates and the same prosthesis. Simultaneously, this data strongly support the theory of individual susceptibility to prosthetic failure., J. Gallo, M. Raška, F. Mrázek, M. Petřek., and Obsahuje bibliografii a bibliografické odkazy
Exercise induced bone response although established, little is known about the molecular components that mediate bone response to mechanical loading (ML). In our recent QTL study, we identified one such possible molecular component responding to ML: cartilage oligomeric matrix protein (COMP). To address the COMP role in mediating ML effects on bone formation, COMP expression was evaluated as a function of duration and age in response to ML in female B6 mice. A 9N load was applied using a four-point bending device at 2Hz frequency for 36 cycles, once per day for 2-, 4- and 12-days on the right tibia. The left tibia was used as an internal control. Loading caused an increase in COMP expression by 1.3-, 2- and 4-fold respectively after 2-, 4- and 12-days of loading. This increase was also seen in 16 and 36-week old mice. Based on these findings, we next used COMP knockout (KO) mice to evaluate the cause and effect relationship. Quantitative analysis revealed 2 weeks of ML induced changes in vBMD and bone size in the KO mice (5.9 % and 21 % vs. unloaded bones) was not significantly different from control mice (7 % and 24 % vs. unloaded bones). Our results imply that COMP is not a key upstream mediator of the anabolic effects of ML on the skeleton., A. Sengul, S. Mohan, C. Kesavan., and Obsahuje seznam literatury
Bone is a target tissue for hormones, such as the sex steroids, parathormon, vitamin D, calcitonin, glucocorticoids, and thyroid hormones. In the last decade, other “non-classic” hormones that modulate the bone tissue have been identified. While incretins (GIP and GLP-1) inhibit bone remodeling, angiotensin acts to promote remodeling. Bone morphogenetic protein (BMP) has also been found to have anabolic effects on the skeleton by activating bone formation during embryonic development, as well as in the postnatal period of life. Bone has also been identified as an endocrine tissue that produces a number of hormones, that bind to and modulate extra-skeletal receptors. Osteocalcin occupies a central position in this context. It can increase insulin secretion, insulin sensitivity and regulate metabolism of fatty acids. Moreover, osteocalcin also influences phosphate metabolism via osteocyte-derived FGF23 (which targets the kidneys and parathyroid glands to control phosphate reabsorption and metabolism of vitamin D). Finally, osteocalcin stimulates testosterone synthesis in Leydig cells and thus may play some role in male fertility. Further studies are necessary to confirm clinically important roles for skeletal tissue in systemic regulations., I. Zofkova., and Obsahuje bibliografii
The evaluation of the head injury criterion (HIC) assessing injuries of a pedestrian when hit by a vehicle, if simply defined, provides no practical hint for designing a bonnet structure with good safety performance. We have studied relations between the time history of the impact, HIC performance and bonnet structure; based on that, we established a method how to define, visualize and remove shortcomings of an existing bonnet design. The abilities of the approach are demonstrated on the results of practical application. and Obsahuje seznam literatury