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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 64 (1999), S. 133-136 
    ISSN: 1432-0827
    Schlagwort(e): Key words: Human fetus — Femur — Densitometry.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. The purpose of this work was to extend to long bones the study on the ossification of human fetal skeleton in relation to conceptual age by a quantitative methodological approach. Postero-anterior scans were performed on 29 dried fetal femora (from 11.5 weeks of conceptual age to term) by a Hologic QDR 1000 X-ray densitometer with Ultra-Hi-Resolution software. The results were expressed as bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2). BMD was calculated on a rectangular area corresponding to the total length and minimum width of the shaft. This area was divided into five equal sections along its longitudinal axis in order to estimate the rate of ossification from a spatio-temporal point of view. Our data show that BMC has a high correlation with conceptual age during the whole prenatal life, increasing in the third trimester (r ≥ 0.96). During development, BMD is progressively less correlated with conceptual age (r = 0.95 in the first half of development, r = 0.68 in the second half), particularly according to a bidirectional gradient from the middle to the proximal and distal ends of the shaft. Our findings confirm the data obtained in our previous studies on the ossification of fetal human spines, and suggest an individual variability in bone density at term of development and particularly at the level of spongiosa, viz. in the areas mostly involved in architectural changes during the morphogenesis of the long bones.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 57 (1995), S. 74-77 
    ISSN: 1432-0827
    Schlagwort(e): Fetus ; Spine ; Ossification ; High resolution densitometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract To define the quantitative aspects of ossification of human fetal spine, we performed a high resolution densitometric study by lateral and postero-anterior scanning of five fetal spines (18–36 weeks of conceptual age) and one spine of a 4-month-old infant. The data were plotted against developmental age for each spine and vertebra. Bone mineral content increased with developmental age, with a peak at the upper lumbar level, in agreement with the ossification pattern of the spine, reported in embryological literature. Bone mineral density (BMD) was unrelated to developmental age, and showed similar trends for each vertebra in all the vertebral columns examined. The changes of BMD seems to be a phenomenon related to individual variability. This study also demonstrates that densitometric techniques may provide useful and interesting information in studies on skeletal development.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 66 (2000), S. 255-258 
    ISSN: 1432-0827
    Schlagwort(e): Key words: Developing human femur — Ossification centers — Bone densitometry — DXA — Ultra-Hi-Resolution.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. The purpose of the present work was to investigate the appearance of ossification centers in human femur by Dual-energy X-ray Absorptiometry (DXA), comparing densitometric data with morphogenetic events. Postero-anterior scans were performed on 31 dried femora (from 11.5 weeks of conceptual age to 1 year of postnatal life) by a Hologic QDR 1000 X-ray densitometer with Ultra-Hi-Resolution software. The results were expressed as bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2). The analyses were performed on a rectangular area corresponding to the minimum width and total length of the shaft. The rectangular area was divided into five equal sections along its longitudinal axis, and BMC was calculated on each section. To distinguish the ossification area of the lesser trochanter with respect to the area of the greater trochanter, the proximal femoral end was divided into two portions, medial and lateral, respectively; BMC and BMD were calculated on each portion. Our data show that the ossification center of the femoral shaft extends prevalently in the proximal direction. A denser area was recognizable on the densitometric images at the level of the lesser trochanter from the 19th week of prenatal life and at the level of the greater trochanter at term. During development, the trends of BMC and BMD are similar in both trochanteric areas, but these parameters are fairly constantly higher at the level of the lesser trochanter. Our findings disagree with the data of the current literature on the postnatal appearance of the trochanteric ossification centers and suggest a different biomechanical interpretation of the secondary ossification of the femur.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 279 (1994), S. 209-213 
    ISSN: 1432-0878
    Schlagwort(e): Key words: Calcium-binding proteins ; Immunohistochemistry ; Mesonephros ; Metanephros ; Chick embryo (White leghorn)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The ontogeny of two calcium-binding proteins (calbindin-D28k and calretinin) was studied by immunohistochemical techniques in developing chick kidney. This study showed the presence of calbindin on the 5th incubation day and calretinin on the 7th incubation day in mesonephric distal and connecting tubules, and in the medial wall of the Wolffian duct. At later stages, immunostaining for these two proteins, in particular for calretinin, was also demonstrated in some metanephric proximal tubules. Glomeruli and Bowman's capsules were negative both in the mesonephros and metanephros. The presence of calretinin in the developing kidney has thus been demonstrated for the first time. The early expression of calbindin and calretinin in mesonephric distal tubules suggests their role in regulating the final excretion of calcium. The different patterns of immunoreactivity of the walls of the Wolffian duct can be correlated with their different histogenetic and histological features.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 279 (1995), S. 209-213 
    ISSN: 1432-0878
    Schlagwort(e): Calcium-binding proteins ; Immunohistochemistry ; Mesonephros ; Metanephros ; Chick embryo (White leghorn)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The ontogeny of two calcium-binding proteins (calbindin-D28k and calretinin) was studied by immunohistochemical techniques in developing chick kidney. This study showed the presence of calbindin on the 5th incubation day and calretinin on the 7th incubation day in mesonephric distal and connecting tubules, and in the medial wall of the Wolffian duct. At later stages, immunostaining for these two proteins, in particular for calretinin, was also demonstrated in some metanephric proximal tubules. Glomeruli and Bowman's capsules were negative both in the mesonephros and metanephros. The presence of calretinin in the developing kidney has thus been demonstrated for the first time. The early expression of calbindin and calretinin in mesonephric distal tubules suggests their role in regulating the final excretion of calcium. The different patterns of immunoreactivity of the walls of the Wolffian duct can be correlated with their different histogenetic and histological features.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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