• MeSH
• CD-ROM MeSH
• Bone Diseases MeSH
• Osteoporosis MeSH
• Bone Demineralization, Pathologic MeSH

• Conspectus
• Ortopedie. Chirurgie. Oftalmologie
• Patologie. Klinická medicína
• NML Fields
• ortopedie
• patologie
• NML Publication type
• CD-ROM

• MeSH
• Biomechanical Phenomena MeSH
• Bone and Bones anatomy & histology   physiology   MeSH
• Tensile Strength MeSH
• Elasticity MeSH

Sekundárně přestavěná (haverská) kost, tvořící stěnu diafýzy kostí člověka, představuje výrazně anizotropní materiál, který má v různých směrech odlišnou pevnost. Jedním z faktorů, které ovlivňují mechanické vlastnosti (zejména pevnost) kosti, je architektonika kompakty. Osteony haverské kosti jsou orientovány do směru dominantního prvního hlavního napětí a vytvářejí dva antirotační šroubovicove systémy v protilehlých stěnách diafýzy. Cílem práce bylo zjistit, jaká je závislost pevnosti kosti v tahu na orientaci osteonů, a prověřit, zda platí předpoklad, že architektonika haverské kosti závisí na směrech prvního hlavního napětí a při jakém poměru momentů pevnosti odpovídá směr prvního hlavního napětí reálné orientaci osteonů. Výsledky zkoušek pevnosti v tahu u vlhkých vzorků z 10 femurů a pevnosti celé diafýzy u 9 párů femuru (pitevní materiál) potvrdily předpoklad, že osteony jsou uspořádány do směrů dominantního prvního hlavního napětí, které závisejí na poměru ohybového a torzního momentUa Pevnost diafýzy femuru je největší při fyziologickém způsobu zatěžování, tj. při ohybu mediálně a při zevní rotaci. Rozhodujícím pohybem, na kterém závisí pevnost kostí, je torze. Při nefyziologlckém způsobu zatěžování diafýzy femuru (opačným ohybovým momentem či opačným torzním momentem při mediálním ohybu) je pevnost kosti výrazně menší. Architektonika haverské kosti má z biomechanického hlediska optimální, účelovou strukturu.

A secondarilly remodelled bone (the haversian bone) forming a wall of human shaft represents a significantly anisotropic material, which has different strengths in different directions. One of the factors influencing mechanical properties (strength in particular) of the bone is the architectonics of the compact bone. Osteons of the haversian bone are arranged in the direction of the dominant first principal stress and create two antirotational spiral systems in the opposite walls of the shaft. The aim of the work was to found out how the bone tensile strength depends on the orientation of osteons and check whether the premise applies that the architectonics of the haversian bone depends on the directions of the first principal stress and in what relation Of Strength moments the direction of the first principal stress corresponds to the actual orientation of osteons. The results of the tensile strength tests in wet samples from 10 femurs and the strength of the whole shaft in 9 pairs of femurs (cadaver material) have confirmed the premise that osteons are arranged in the directions of the dominant first principal stress and depend on the relation between bending and torsion moments. The strength of the femoral shaft is maximal in the physiological way of loading, i.e. in medial bending and outer rotation.The decisive motion on which the strength of the bone depends is torsion. In non-physiological loading the femoral shaft (by an opposite bending moment or opposite torsion moment in medial bending) the Strength of the bone is significantly lower. From the biomechanical viewpoint the architecture of the haversian bone has an optimal and efficient structure.

• MeSH
• Biomechanical Phenomena MeSH
• Diaphyses analysis   physiology   blood supply   MeSH
• Femur MeSH
• Humans MeSH
• Tensile Strength MeSH
• Bone Remodeling MeSH
• Exercise Test MeSH
• Check Tag
• Humans MeSH
• Publication type
• Comparative Study MeSH

• MeSH
• Biomechanical Phenomena MeSH
• Fractures, Bone MeSH
• Spinal Fractures ultrastructure   MeSH
• Bone Density MeSH
• Bone Matrix ultrastructure   MeSH
• Osteoporosis MeSH

• Conspectus
• Patologie. Klinická medicína
• NML Fields
• revmatologie
• ortopedie

BACKGROUND: Sarcopenia and osteoporosis are among the late complications of type 1 diabetes (T1D) in adults. Whether and to what extent musculoskeletal impairment is present in childhood and adolescence has yet to be determined. The aim of this study was to assess volumetric bone mineral density (BMD) and dynamic muscle function in adolescents with T1D and to assess the clinical and biochemical predictors of their musculoskeletal system. METHODS: Ninety-five children and adolescents (59 boys and 36 girls, mean age 16.2±1.2years) with T1D were included in this cross-sectional study. Study participants were divided into two groups according to the duration of the disease (<6years and >9years, respectively). Volumetric BMD of the non-dominant tibia was assessed using peripheral quantitative computed tomography (pQCT). Dynamic muscle function was evaluated using jumping mechanography. Gender- and height-specific Z-scores were calculated using published reference data. HbA1c was evaluated retrospectively as an average over the past 5years. RESULTS: Relative muscle power (Pmax/mass) and force (Fmax/body weight) were significantly decreased in T1D subjects (mean Z-scores -0.4±1.0; p<0.001, and -0.3±1.1; p<0.01, respectively). The duration of T1D negatively affected Pmax/mass (p<0.01) but not Fmax/body weight (p=0.54). Patients with T1D had also decreased trabecular BMD, the Strength-Strain Index and cortical thickness (mean Z-scores -0.8±1.3; -0.5±0.8 and -1.1±0.8, respectively, p<0.001 for all) whereas cortical BMD was increased when compared to controls (Z-score 1.2±0.90, p<0.001). No association was observed between the HbA1c and 25-hydroxyvitamin D levels and bone or muscle parameters. CONCLUSION: T1D influences the musculoskeletal system in adolescence. Decreased muscle function could contribute to the osteoporosis reported in adult diabetic patients.

• MeSH
• Anthropometry MeSH
• Diabetes Mellitus, Type 1 physiopathology   MeSH
• Adult MeSH
• Bone and Bones physiology   MeSH
• Bone Density physiology   MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Tomography, X-Ray Computed MeSH
• Cross-Sectional Studies MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

• MeSH
• Absorptiometry, Photon methods   instrumentation   utilization   MeSH
• Densitometry methods   instrumentation   utilization   MeSH
• Child MeSH
• Financing, Organized MeSH
• Fractures, Bone diagnosis   etiology   MeSH
• Bone Density drug effects   MeSH
• Humans MeSH
• Magnetic Resonance Imaging methods   instrumentation   utilization   MeSH
• Adolescent MeSH
• Osteoporosis diagnosis   etiology   physiopathology   MeSH
• Bone Demineralization, Pathologic diagnosis   ultrasonography   MeSH
• Tomography, X-Ray Computed methods   instrumentation   utilization   MeSH
• Radiography methods   instrumentation   utilization   MeSH
• Risk Factors MeSH
• Muscle Strength MeSH
• Ultrasonography methods   instrumentation   utilization   MeSH
• Age Factors MeSH
• Bone Development physiology   drug effects   MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Adolescent MeSH

OBJECTIVE: Some data suggest that exposure to lamotrigine (LTG) might be associated with impaired bone health in an orchidectomized rat model. The aim of this study was to determine if LTG poses any significant risk for bone in a gonadally intact animals and to compare the effect of LTG with that of phenytoin (PHT). METHOD: Twenty-four rats were divided into control and test groups, (n=8 per group). Control rats received a standard laboratory diet (SDL), while rats in the test groups were fed a SLD enriched with LTG or PHT for 12 weeks. Dual energy X-ray absorptiometry was used to measure bone mineral density (BMD). The concentrations of bone turnover markers (BTM) were assayed in bone homogenates. The femurs were measured and biomechanically tested. RESULTS: Treatment with either LTG or PHT had no significant effect on BMD or on the biomechanical strength of the bones. In contrast to the effect of LTG, we did find significant changes in BTM in the PHT group: a highly significant decrease in the osteoprotegerin/receptor activator of nuclear factor kappa B ratio (p<0.01) and highly significant increases in bone alkaline phosphatase and amino-terminal propeptide of procollagen type I (p<0.001, p˂0.01, respectively). In the LTG group, the only significant change was a decrease in sclerostin (p˂0.05). The PHT level was 19.0 (15.6-19.5) μmol/l, which represents the lower end of the therapeutic range used in humans. The level of LTG was 60.7 (58.5-61.8) μmol/l. CONCLUSIONS: LTG has no effect on the BMD, BTM or mechanical strength in gonadally intact animals. Although a low dose of PHT was associated with enhanced BTM, it did not affect BMD or the biomechanical properties of the bones, similar to the results observed for LTG.

• MeSH
• Absorptiometry, Photon MeSH
• Anticonvulsants pharmacology   MeSH
• Biomarkers metabolism   MeSH
• Biomechanical Phenomena MeSH
• Phenytoin pharmacology   MeSH
• Bone and Bones diagnostic imaging   drug effects   physiology   MeSH
• Bone Density drug effects   physiology   MeSH
• Longitudinal Studies MeSH
• Rats, Wistar MeSH
• Prospective Studies MeSH
• Bone Remodeling drug effects   physiology   MeSH
• Triazines pharmacology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH

Tobacco, containing nicotine as the principal pharmacologically active chemical, has been identified as being a risk factor for the development of osteoporosis. Thirty-two male Wistar rats of two months of age were castrated or sham operated to evaluate the effects of long-term administration (four months) of nicotine in drinking water (9.0 mg/kg/day). The presence of cotinine in urine confirmed successful delivery of nicotine. The bones were tested mechanically by a three point bending test in a Mini Bionix (MTA) testing system. The bones from castrated rats were characterized by a reduction in bone density as well as ash, calcium and phosphate content. Castration significantly altered mechanical properties of bone (9%) and femoral cortical thickness. When intact rats were treated with a high dose of nicotine, nicotine had negative effect on tibial bone density as well as ash, calcium, phosphate content and significantly altered the mechanical properties of bone (12%) and femoral cortical thickness compared to intact animals. Nicotine itself does not exert any anti-androgenic effect and does not produce changes in the weight of seminal vesicles. Nicotine-induced bone loss is associated with high bone turnover in the male rats as expressed by increased TrACP and B-ALP. When castrated rats were treated with the high dose of nicotine the changes in bone density resulting from castration were not further potentiated. These results document the efficacy of nicotine at high doses to cause bone loss and loss of bone mechanical strength in intact rats. The results of the present study may be interpreted as supporting the hypothesis of nicotine as a risk factor for osteoporosis.

• MeSH
• Alkaline Phosphatase blood   MeSH
• Time MeSH
• Femur drug effects   MeSH
• Financing, Organized MeSH
• Evaluation Studies as Topic MeSH
• Bone Density drug effects   MeSH
• Rats MeSH
• Nicotine administration & dosage   pharmacology   MeSH
• Orchiectomy MeSH
• Compressive Strength drug effects   MeSH
• Rats, Wistar MeSH
• Tibia drug effects   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Comparative Study MeSH

Alcohol use has been identified as a risk factor for the development of osteoporosis. Eight male Wistar rats at two months of age were alcoho-fed (7.6 g 95 % ethanol/kg b.w. per day) to evaluate the effects of long-term administration (three months) of alcohol in drinking water. We have used a dose which is considered to be comparable to a dose of 1 liter of wine or 2.5 liters of 12° beer used in male adults daily. The bones were tested mechanically by a three-point bending test in a Mini Bionix (MTS) testing system. The bones from alcohol-fed rats were characterized by a reduction in bone density as well as in ash, calcium and phosphate content. In alcohol-fed rats the reduction in bone mineral density (10 %) was reflected by about 12 % reduction of mechanical strength of femur (158±5.5 vs. 178±3.2 N/mm2). Alcohol significantly altered femoral cortical thickness. In our experiment alcohol itself did not exert any antiandrogenic effect and it did not produce changes in the weight of seminal vesicles. Liver function test (GGT, ALP, AST) did not differ between alcohol-fed rats and control rats. Alcohol-induced bone loss is associated with increased bone resorption and decreased bone formation. These results document the efficacy of alcohol at the dose of 7.6 g 95 % ethanol/kg b.w. to cause bone loss and loss of bone mechanical strength in intact rats. The results of the present study may be interpreted as supporting the hypothesis of alcohol as a risk factor for osteoporosis.

• MeSH
• Biomarkers MeSH
• Biomechanical Phenomena MeSH
• Time Factors MeSH
• Enzymes blood   MeSH
• Ethanol administration & dosage   toxicity   MeSH
• Femur metabolism   pathology   drug effects   MeSH
• Financing, Organized MeSH
• Phosphates blood   MeSH
• Liver Function Tests MeSH
• Liver enzymology   drug effects   MeSH
• Bone Density drug effects   MeSH
• Rats MeSH
• Osteogenesis drug effects   MeSH
• Osteoporosis chemically induced   metabolism   pathology   MeSH
• Alcohol Drinking MeSH
• Rats, Wistar MeSH
• Bone Resorption chemically induced   metabolism   pathology   MeSH
• Seminal Vesicles drug effects   MeSH
• Calcium blood   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH

Although a decreased areal bone mineral density (BMD) has been reported in patients with haemophilia, data are lacking that would reflect the three-dimensional structure of the bone and the muscle-bone relationship. We aimed to assess volumetric BMD, bone geometry and muscle-bone phenotype in boys with haemophilia, and to describe the association between clinical characteristics of haemophilia and bone quality and structure. A cross-sectional study was conducted in 41 boys with haemophilia (mean age 12.4, range 6.6-19.8 years) using peripheral quantitative CT (pQCT) at the nondominant forearm. Results were transformed into Z-scores using previously published reference data. Significant differences were tested by one-sample t-test or sign test. Two-sample t-test and anova were used to compare results between subgroups of patients divided according to the severity of the disease, the fracture history and the number of joint and muscle bleedings. Boys with haemophilia had a decreased trabecular volumetric BMD (mean Z-score -0.5, P < 0.01), while their cortical volumetric BMD was increased (mean Z-score 0.4, P < 0.05). The volumetric bone mineral content and the bone geometry at the radial diaphysis were normal when adjusted for patients' shorter body height. Muscle area was decreased (mean Z-score -1.0, P < 0.001), irrespective of age. No association was observed of bone quality parameters and bone geometry with the disease severity, fracture history or number of bleedings. Bone strength measured at the diaphysis of the radius is not impaired in boys with haemophilia. The finding of the decreased trabecular bone density can be most likely attributed to their sarcopenia.

• MeSH
• Analysis of Variance MeSH
• Child MeSH
• Hemophilia A complications   physiopathology   MeSH
• Muscle, Skeletal physiology   MeSH
• Bone Density physiology   MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Musculoskeletal System physiopathology   MeSH
• Cross-Sectional Studies MeSH
• Radius physiopathology   MeSH
• Reference Values MeSH
• Sarcopenia etiology   MeSH
• Muscle Strength physiology   MeSH
• Trabecular Meshwork physiopathology   MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH