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  • Cell & Developmental Biology  (2)
  • Oestrogen  (1)
  • Polymer and Materials Science  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International orthopaedics 7 (1984), S. 209-214 
    ISSN: 1432-5195
    Keywords: Bone mineral content ; Exercise ; Women ; Osteoporosis ; Oestrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs ont comparé, par photo-absorptiométrie de l'extrémité inférieure du radius, les effets de la marche et de la danse «aerobic« sur l'os de 73 femmes récemment ménopausées en les comparant à un groupe de contrôle ne pratiquant aucun exercise. L'observation a porté sur une période de six mois. Les résultats montrent que le groupe de contrôle et celui qui pratique la marche présentent une déminéralisation osseuse statistiquement significative (1,6% et 1,7% respectivement), contrairement au groupe pratiquant la danse (0,8%). Il n'y a pas d'augmentation significative de la largeur de l'os dans le groupe de contrôle (0,9%), alors qu'elle est importante aussi bien dans le groupe de danse (1,3%) que dans le groupe de marche (1,6%). On a calculé chez chaque sujet, à l'aide des mesures de la teneur en minéraux et de la largeur de l'os, le moment d'inertie d'une section horizontale du radius. Les deux groupes pratiquant un exercise présentent une augmentation significative de cette variable, tandis qu'il n'y en a pas dans le groupe de contrôle. Le taux d'oestrogène plasmatique n'est pas influencé par l'exercise. Ces résultats confirment l'hypothèse selon laquelle les contraintes mécaniques entraînées par l'exercise pourraient prévenir efficacement l'ostéoporose post-ménopausique.
    Notes: Summary The effects of walking and aerobic dancing on the bones of 73 recently postmenopausal women have been compared by photon absorptiometry of the distal radius with a control group who did not exercise. The period of observation was six months. Results showed that the control group and the walking group lost statistically significant amounts of bone mineral content (1.6%, and 1.7% respectively), but that the dancing group did not (0.8%). The control group did not show a significant increase in the bone width (0.9%), but both the dancing (1.3%) and walking (1.6%) groups did. Changes in the cross-sectional moment of inertia of the radius were estimated for each subject based on bone mineral content and bone width values. Both exercise groups experienced significant increases in this variable, while the control group did not. Plasma oestrogen levels were not influenced by exercise. The results support the hypothesis that mechanical loading due to exercise may be effective in preventing postmenopausal osteoporosis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 351-353 
    ISSN: 0006-3525
    Keywords: free energy of hydrolysis ; glycyl peptides ; hydrolysis ; peptides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For every n amino acids linked in a protein there are n - 1 peptide bonds. The free energy of peptide bond hydrolysis and formation in aqueous solution defines the equilibrium position between peptide and amino acid hydrolysis products. Yet few experimental values exist. With a minimum of assumptions, this paper deduces the free energies of hydrolysis of a variety of peptide bonds. Formation of a dipeptide from two amino acids is about eight times more difficult than subsequent condensations of an amino acid to a dipeptide or longer chain. Condensation of an amino acid to a peptide of any size is five times more difficult than joining two smaller peptides of at least dipeptide size. Thus in an abiogenesis scenario there is a kind of nucleation in peptide bond formation with the initial condensation of two amino acids to yield a dipeptide more difficult than subsequent condensations to a growing chain. © 1998 John Wiley & Sons, Inc. Biopoly 45: 351-353, 1998
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 202 (1982), S. 419-429 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: One method used to examine the relationship between behavioral strategies and anatomical adaptation is to study the results of mechanical stress associated with a given behavior and compare this with skeletal adaptations to other behaviors. This comparative approach is appropriate for highlighting combinations of features that are specializations to specific types of behavior. The purpose of this paper is to compare femoral mechanics in Galago senegalensis with previously collected data for macaques and humans as a basis for discussing structural adaptations in the primate hindlimb to leaping. The stiffness and load carrying capabilities of the femoral diaphyses of 27 G. senegalensis were analyzed using the SCADS computer program. The data suggest that the galago femur is well adapted to sustain large sagittal plane compressive loads rather than large bending loads. The straightness of the femoral shaft and large midshaft area moments of inertia prevent buckling from these large compressive loads. Calculations indicate that the ratio of critical buckling load to body weight in galago is 31 times that in macaques and 55 times that in humans. The femur of this saltatory primate is morphologically adapted to resist buckling when subjected to large compressive loads, while those of macaques and humans are better adapted to resist bending moments caused by ground reaction forces acting on the extended limb. The differences between galago on the one hand and macaques and humans on the other suggest that relatively smaller moments about the hip and relatively larger moments about the knee accompany more quadrupedal and bipedal walking, while habitual leaping is associated with relatively larger moments about the hip. These data reinforce the apparent similarity of the mechanical effects of quadrupedal and bipedal locomotion on the femur and dissimilarity with femoral mechanics in habitually saltatory primates.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 186 (1989), S. 186-216 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Recent evidence suggests that skeletal adaptation is organized by a functional unit that includes cells of diverse origin working in coordination. Genetic and metabolic factors control and regulate the processes of modeling and remodeling, only rarely acting on the isolated individual functions of specific cell lines. Errors in the genetic or metabolic regulation of the functional unit affect the entire process of skeletal adaptation rather than specific elements of it. Viewed in this way, some metabolic bone diseases can be understood as relatively simple errors in factors that control the coordinated activities of the entire functional unit. This paper reviews the modeling and remodeling processes and demonstrates how abnormal morphological characteristics of bone tissue can be viewed as products of specific errors in the adaptive process.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
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