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  • 1
    Electronic Resource
    Electronic Resource
    Functional associations between collagen fibre orientation and locomotor strain direction in cortical bone of the equine radius (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 231-238 
    Details
    ISSN: 1432-0568
    Keywords: Bone ; Collagen ; Orientation ; In vivo strain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A novel technique for determining the collagen fibre orientation pattern of cross-sections of cortical bone was used to study mid-diaphyseal sections from the equine radius. Several in vivo strain gauge studies have demonstrated that this bone is loaded in bending during locomotion in such a way that the cranial cortex is consistently subjected to longitudinal tensile strains and the caudal cortex to longitudinal compressive strains. Twenty-three radii from 17 horses were studied. All the bones obtained from adult horses exhibited a consistent pattern of collagen fibre orientation across the cortex. The cranial cortex, subjected to intermittent tension, and the lateral and medial cortices, through which the neutral axis passes, contained predominantly longitudinally oriented collagen fibres. The caudal cortex, subjected to longitudinal compression during life, contained predominantly oblique/transverse collagen. This pattern was less evident in bones from foals. Microscopic analysis of the bones studied showed that primary lamellar bone was composed of predominantly longitudinal collagen fibres, irrespective of cortex. However, there was a strong relationship between cortical location and fibre orientation within remodelled bone. Secondary osteons which formed in the caudal (compressive) cortex contained predominantly oblique/transverse collagen, while those which formed elsewhere contained longitudinal collagen. This observation explained the developmental appearance of the characteristic macroscopic pattern of collagen fibre orientation across the whole cortex in the adult. These findings provide evidence for the existence of a relationship between the mechanical function of a bone with its architecture, and now demonstrate that it extends to the molecular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195760
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanical implications of collagen fibre orientation in cortical bone of the equine radius (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 239-248 
    Details
    ISSN: 1432-0568
    Keywords: Collagen orientation ; Bone ; Stress ; Strain ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mechanical test specimens were prepared from the cranial and caudal cortices of radii from eight horses. These were subjected to destructive tests in either tension or compression. The ultimate stress, elastic modulus and energy absorbed to failure were calculated in either mode of loading. Analysis was performed on the specimens following mechanical testing to determine their density, mineral content, mineral density distribution and histological type. A novel technique was applied to sections from each specimen to quantify the predominant collagen fibre orientation of the bone near the plane of fracture. The collagen map for each bone studied was in agreement with the previously observed pattern of longitudinal orientation in the cranial cortex and more oblique to transverse collagen in the caudal cortex. Bone from the cranial cortex had a significantly higher ultimate tensile stress (UTS) than that from the caudal cortex (160 MPa vs 104 MPa; P〈0.001) though this trend was reversed in compression, the caudal cortex becoming relatively stronger (185 MPa vs 217 MPa; P〈0.01). Bone from the cranial cortex was significantly suffer than that from the caudal cortex both in tension (22 GPa vs 15 GPa; P〈0.001) and compression (19 GPa vs 15 GPa; P〈0.01). Of all the histo-compositional variables studied, collagen fibre orientation was most closely correlated with mechanical properties, accounting for 71% of variation in ultimate tensile stress and 58% of variation in the elastic modulus. Mineral density and porosity were the only other variables to show any significant correlation with either UTS or elastic modulus. The variations in mechanical properties around the equine radius, which occur in close association with the different collagen fibre orientations, provide maximal safety factors in terms of ultimate stress, yet contribute to greater bending of the bone as it is loaded during locomotion, and thus lower safety factors through the higher strains this engenders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195761
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  • 3
    Electronic Resource
    Electronic Resource
    Strain related electrical potentials recorded in vitro and in vivo (1977)
    Springer
    Calcified tissue international 22 (1977), S. 315-327 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Bioelectricity ; Strain ; Locomotion ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Using wet dead specimens it was possible to show that the size and form of strain-related electrical potentials on the surface of sheep radii were related both to the amount of strain, and the strain rate, over the range of these recorded during locomotion. Using the same electrode and amplifier system in vivo changes in surface strain and surface charge were recorded from the radius of three sheep during locomotion. During slow locomotion electrical changes were negligible. At medium speed they were most variable, and profoundly influenced by small alterations in the timing and pattern of strain change. When locomotion was fast the electrical waveform reflected fairly faithfully the changes in strain on the bone surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010370
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  • 4
    Electronic Resource
    Electronic Resource
    Noninvasive loading of the rat ulna in vivo induces a strain-related modeling response uncomplicated by trauma or periostal pressure (1994)
    Springer
    Calcified tissue international 54 (1994), S. 241-247 
    Details
    ISSN: 1432-0827
    Keywords: Loading ; Strain ; Modeling ; Rat ; Ulna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Adaptive changes in bone modeling in response to noninvasive, cyclic axial loading of the rat ulna were compared with those using 4-point bending of the tibia. Twenty cycles daily of 4-point bending for 10 days were applied to rat tibiae through loading points 23 and 11 mm apart. Control bones received nonbending loads through loading points 11 mm apart. As woven bone was produced in both situations, any strain-related response was confounded by the response to direct periosteal pressure. Four-point bending is not, therefore, an ideal mode of loading for the investigation of strain-related adaptive modeling. The ulna's adaptive response to daily axial loading over 9 days was investigated in 30 rats. Groups 1–3 were loaded for 1200 cycles: Group 1 at 10 Hz and 20 N, Group 2 at 10 Hz and 15 N, and Group 3 at 20 Hz and 15 N. Groups 4 and 5 received 12,000 cycles of 20 N and 15 N at 10 Hz. Groups 1 and 4 showed a similar amount of new bone formation. Group 4 showed the same pattern of response but in reduced amount. The responses in Groups 2 and 3 were either small or absent. Strains were measured with single-element, miniature strain gauges bonded around the circumference of dissected bones. The 20 N loading induced peak strains of 3500–4500 μstrain. The width of the periosteal new bone response was proportional to the longitudinal strain at each point around the bone's circumference. It appears that when a bone is loaded in a normal strain distribution, an osteogenic response occurs when peak physiological strains are exceeded. In this situation the amount of new bone formed at each location is proportional to the local surface strain. Cycle numbers between 1200 and 12,000, and cycle frequencies between 10 and 20 Hz have no effect on the bone's adaptive response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301686
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  • 5
    Electronic Resource
    Electronic Resource
    On animal models for studying bone adaptation (1994)
    Springer
    Calcified tissue international 55 (1994), S. 316-318 
    Details
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310412
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  • 6
    Electronic Resource
    Electronic Resource
    Functional strain as a determinant for bone remodeling (1984)
    Springer
    Calcified tissue international 36 (1984), S. S56 
    Details
    ISSN: 1432-0827
    Keywords: Mechanical strain ; Bone remodeling ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Mechanical function has always been acknowledged to have a significant, continuing but hitherto unquantified influence on bone remodeling. The structural objective of this relationship is presumably to ensure that, at each location throughout the skeleton, there is sufficient bone tissue, appropriately placed, to withstand functional load-bearing without damage. The architectural modifications necessary to achieve and maintain this structural competence are made by the coordinated remodeling activity of populations of osteoblasts and osteoclasts. The specific structure-function objectives at each location remain undefined, as are the mechanisms by which tissue loading is transduced into cellular control. The remodeling responses following a variety of experimental alterations in bones' strain environment are presented. Their significance to the process of remodeling control is discussed, and a scheme for the interaction of mechanical and hormonal influences proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02406134
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  • 7
    Electronic Resource
    Electronic Resource
    Osteocytes, strain detection, bone modeling and remodeling (1993)
    Springer
    Calcified tissue international 53 (1993), S. S102 
    Details
    ISSN: 1432-0827
    Keywords: Osteocytes, strain ; Modeling/remodeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary One of the characteristic features of mammalian and avian bone is a population of live cells of the osteoblast lineage distributed both on the surface and throughout the matrix. These cells communicate with one another via gap junctions. A number of roles have been proposed for both osteocytes and the lacunar/canalicular labyrinth they oc cupy. These include arrest of fatigue cracks, mineral exchange, osteocytic osteolysis, renewed remodeling activity after release by resorption, stimulation, and guidance of osteoclastic cutting cones involved in mineral exchange and the repair of microdamage, strain detection, and the control of mechanically related bone modeling/remodeling. The question of whether osteocytes control or influence modeling and remodeling is of major importance. Such influence could be crucial in relation to three importance consequences of remodeling activity: calcium regulation, microdamage repair, and mechanically adaptive control of bone architecture. Mechanically adaptive control of bone architecture requires feedback concerning the relationship between current loading and existing architecture. This feedback is most probably derived from the strain in the matrix. The arrangement of the osteocyte network seems ideally suited to both perceive strain throughout the matrix and to influence adaptive modeling and remodeling in a strain-related manner. The hypothese that osteocytes perform this role has growing experimental support.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01673415
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  • 8
    Electronic Resource
    Electronic Resource
    Ineffectiveness of calcitonin on a local-disuse osteoporosis in the sheep: A histomorphometric study (1995)
    Springer
    Calcified tissue international 57 (1995), S. 224-228 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Disuse ; Calcitonin ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Local immobilization is a good model for studying disuse-induced bone loss and to appreciate the effects of drugs, especially preventive action of antiresorptive therapy. In fact, increased osteoclastic activity is the main point of such a bone loss. The effect of salmon calcitonin was investigated on immobilization-induced osteoporosis in the sheep. Twenty-four nonovariectomized, adult, female, Welsh mountain sheep were submitted, by an external fixator procedure, to hock joint immobilization from the tibia to the the metatarsus for 12 weeks. The sheep were randomized into two groups receiving either an injection of placebo or salmon calcitonin (100 IU) three times per week, for 12 weeks. Histomorphometric analysis was performed on pre-and posttherapeutic transiliac bone biopsies, and on immobilized (left) and nonimmobilized calcanei removed after sacrifice. Results showed a 29% significant decrease of cancellous bone volume in the placebo group due to a significant reduced trabecular thickness when we compared immobilized versus nonimmobilized calcaneus. This structural adaptation appeared to be the consequence of an overall increased bone turnover. In the calcitonin group, same changes were observed, with a 23% reduction of bone mass in the immobilized calcaneus. By comparing calcitonin with placebo groups in both left and right calcanei, no difference was found. On the other hand, a significant increase of mineralization parameters in the iliac crest was only observed in the calcitonin group. In conclusion, salmon calcitonin, at a dose of 100 IU/day three times a week, was ineffective in preventing local disuse osteoporosis in this sheep model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310263
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of fungal-soil water interactions on phytophthora root rot of alfalfa (1985)
    Springer
    Biology and fertility of soils 1 (1985), S. 91-96 
    Details
    ISSN: 1432-0789
    Keywords: Phytophthora megasperma ; Alfalfa ; Moisture regime ; Root rot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Phytophthora root rot of alfalfa (Medicago sativa L.) is a serious problem in wet soils. This disease is caused by Phytophthora megasperma f. sp. medicaginis. The influence of soil-water interactions with P. megasperma f. sp. medicaginis and other factors on the severity of phytophthora root rot of mature alfalfa plants (10–12 weeks) was studied in greenhouse experiments. Severe and reproducible root rot was produced by subsurface (3–4 cm) placement of mycelial suspension. Soil saturation 3 days prior to inoculation followed by alternating 3-day wet (soil saturation) and 4-day dry (surface watering once a day) moisture regimes (for 30–40 days following inoculation) resulted in severe root damage. The severity of root rot was greater when the inoculation was done at an ambient temperature of 20°C than at 15°C. Water quality (tap water or deionized distilled water) had no effect on severity of infection. The isolates PT 78-3 (Minnesota) and TN-2 (Maryland) were equally effective in terms of severity of damage. The impact of excess soil water stress (described above) alone on the shoot and root dry weight as well as on shoot symptoms was similar to that of root rot stress. However, root symptoms showed a marked difference. A close examination of root symptoms is highly recommended to differentiate clearly the plant injury due to root rot from that due to excess soil water stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00255135
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  • 10
    Electronic Resource
    Electronic Resource
    Loading-related reorientation of bone proteoglycan in vivo. Strain memory in bone tissue? (1988)
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 6 (1988), S. 547-551 
    Details
    ISSN: 0736-0266
    Keywords: Bone tissue ; Proteoglycan ; Bone strain ; Dynamic loading ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The load-carrying capacity of the skeleton is achieved and maintained as the result of a continued functional stimulus to the cell populations responsible for bone remodeling. Although some bone cells have been assumed to be influenced by the load-induced changes in strain throughout the matrix, no evidence is available to indicate which cells are susceptible to such strain change or how such transient events provide a sustained influence on cell behaviour. In the present study, we showed that a short period of dynamic loading in vivo affects the orientation of proteoglycan within bone tissue. This reorientation declines only slowly, thus providing a persistent record of the tissue's recent strain history. Such a record has the ability not only to “capture” strain transients but also to “update” and “average” them. In this way, the bone cells could be presented with a sustained and coherent stimulus directly related to dynamic strain transients. These transients are the tissue's principal function variable.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jor.1100060411
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