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  • 1
    Digitale Medien
    Digitale Medien
    Evolution of Lumbar Bone Mineral Content During Adolescence and Adulthood: A Longitudinal Study in 395 Healthy Females 10–24 Years of Age and 206 Premenopausal Women (1999)
    Springer
    Osteoporosis international 9 (1999), S. 476-482 
    Details
    ISSN: 1433-2965
    Schlagwort(e): Key words:Adolescents – Bone mineral density – Prospective study – Spine – Women
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract: In a longitudinal study of 395 normal 10- to 24-year-old female volunteers, 105 of whom were initially premenarcheal, lumbar bone mineral density (BMD) and content (BMC) were measured by dual-energy X-ray absorptiometry (DXA) at inclusion and after a 2-year interval. The mean age of menarche was 13.1 þ 1.1 years (n = 395). In a multiple regression analysis the BMD and BMC relative gains were highly correlated with the height and weight relative gains and with the time since menarche (r= 0.91 and r= 0.93, respectively). The mean relative annual increments in body height, in L2–4 vertebral height, in BMD and in BMC peaked respectively at 1.5, 1.0, 0.6 and 0.7 years before menarche. The four perimenarcheal years, beginning with the first pubertal clinical signs, are essential for bone acquisition, since 46.7% of adult BMC is acquired during this period. Two years after menarche, BMC is 85% of the adult value. Seven years after menarche no further significant variation in BMC is observed. In 206 menstruating women 27–47 years old, a DXA lumbar measurement was also performed after a 4-year interval. There was a small but significant increase of 0.3 %/year in BMD and 0.7 %/year in BMC, contrasting with the results in the young population. This could be explained by a volumetric expansion with aging, which is supported by a small increase in L2–4 area (0.4 %/year). In conclusion, this longitudinal study on the lumbar site emphasizes the importance of the pre- and perimenarcheal period, when half of lumbar adult BMC is acquired. This suggests that greater attention must be paid to this period regarding nutrition and physical activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001980050173
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  • 2
    Digitale Medien
    Digitale Medien
    Bone mineral acquisition during adolescence and early adulthood: A study in 574 healthy females 10–24 years of age (1996)
    Springer
    Osteoporosis international 6 (1996), S. 141-148 
    Details
    ISSN: 1433-2965
    Schlagwort(e): Bone mineral density ; Females ; Insulin-like growth factor 1 ; Osteocalcin ; Peak bone mass ; Puberty
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Low bone mass is known to be associated with an increased risk of fractures. Osteoporosis prevention by maximizing bone mass will be crucial and requires a better knowledge of bone mass acqusition during adolescence. Bone mass was assessed in 574 healthy volunteer females aged 10–24 years. Spine bone mineral density (BMD) in anteroposterior (AP L2–4) and lateral (LAT L3) views was measured using dual-energy X-ray absorptiometry (DXA) and AP bone mineral content (BMC) was calculated. At the same time, spine AP-BMD (L2–4) was evaluated in 333 normal menstruating women, aged 27–47 years. Bone values, osteocalcin and IGF-1 serum concentrations were correlated with chronological age, skeletal age, pubertal stages and time after menarche. In this cross-sectional study, AP- and LAT-BMD and BMC increased dramatically between skeletal ages 10 and 14 or until the first year after menarche. Between 14 and 17 skeletal years of age, AP-BMD and BMC increased moderately, whereas LAT-BMD remained unchanged. After skeletal age 17, or the fourth year after menarche, there was no significant increase in BMD or BMC, and their values did not differ from those of menstruating women. A serum osteocalcin peak was observed at skeletal ages 11–12 or at stage P3, whereas IGF-1 peaked at 13–14 skeletal years of age or at P4 and the first year after menarche. Eighty-six per cent of the adult bone mass of the spine is acquired before skeletal age 14 or the second year after menarche; therefore osteoporosis prevention programs will be particularly effective before that age.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01623938
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  • 3
    Digitale Medien
    Digitale Medien
    Comparison and Cross-Calibration of DXA Systems: ODX-240 and Sophos L-XRA versus Hologic QDR-4500, for Spinal Bone Mineral Measurement. Translation of a Reference Database (1998)
    Springer
    Osteoporosis international 8 (1998), S. 570-577 
    Details
    ISSN: 1433-2965
    Schlagwort(e): Key words:Bone mineral density – Cross-calibration – Densitometry – Lumbar vertebrae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract: Replacement of dual-energy X-ray densitometry equipment may be necessary in time as a result of upgrading systems or new equipment. The lack of standardization in bone mineral density (BMD) measurements is known. Standardization efforts have been made for several years by the European Union under its organization COMAC-BME (Comité d'Actions Concertés–BioMedical Engineering) and by the International Committee for Standards in Bone Measurement. Cross-calibration is generally considered to be the result of linear regression between the measurements obtained with two densitometers. A major disadvantage of the regression method is the noncompatibility of the two formulae of calibration (Y versus X and X versus Y). In this study we considered cross-calibration in terms of a structural model that produced circular equations when, for example, three systems were cross-calibrated. Cross-calibration in this study was calculated from the measurement of the lumbar BMD of a population of 204 patients, with Hologic QDR-4500, ODX-240 and Sophos L-XRA systems. In vitro accuracy and short-term reproducibility of the three systems were studied. Using the structural calibration equation we transformed a reference database for L2–4 BMD obtained from a population of 983 French females, aged 11–47 years, on an ODX-240 to a reference database for a Hologic QDR-4500. A new young adult reference was obtained and consequently a new evaluation of the T-score for the Hologic QDR-4500.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001980050101
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  • 4
    Digitale Medien
    Digitale Medien
    In corticosteroid-treated respiratory diseases, monofluorophosphate increases lumbar bone density: A double-masked randomized study (1996)
    Springer
    Osteoporosis international 6 (1996), S. 171-177 
    Details
    ISSN: 1433-2965
    Schlagwort(e): Bone mineral density ; Calcium ; Corticosteroid ; Double-masked procedure ; Monofluorophosphate ; Osteopenia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The efficacy of a monofluorophosphate-calcium combination (MFP-Ca) in increasing lumbar bone mineral density (BMD) was assessed in a prospective double-masked study. Patients (n=35), who had been treated for 1 year or more with prednisone-equivalent doses ⩾7 mg/day for asthma or other respiratory diseases, were randomly assigned to receive twice a day, for 2 years, either one MFP-Ca tablet [100 mg sodium monofluorophosphate (13.2 mg F−)+500.5 mg Ca2+] or one Ca tablet (500.5 mg Ca2+). BMD was measured from L2 to L4 using a dual photon absorptiometer. The eligible patients (7 premenopausal women, 21 men), who had no previous vertebral fractures and were aged 46.5 (21–65) years, had received 18 (7.5–60) mg prednisone-equivalent/day and had a mean lumbar BMD of 0.917±0.141 g/cm2 at baseline (M0); in these 28 patients, the mean increase in lumbar BMD at final assessment was significantly greater in the MFP-Ca group (p=0.05; Mann-Whitney). There was also a significant difference after 2 years between the two groups (p= 0.05, ANOVA) in favour of MFP-Ca, with an increase in lumbar BMD of 11% (MFP-Ca) compared with 1% (Ca); thus, with MFP-Ca, lumbar BMD increased by an average of approximately 5.5%/year. There was no statistically significant difference between the two groups in doses of corticosteroids used during the 2 study years, rate of vertebral fractures, or frequency of side-effects (which were all minor). No bone fissure was observed. Thus, the daily dose of 200 mg monofluorophosphate (26.4 mg F−) combined with 1 g Ca2+ in patients with long-term corticosteroid-treated respiratory diseases appears to be a safe and efficient way of increasing lumbar BMD, suggesting that its use should be further studied in corticosteroid-induced osteoporosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01623943
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  • 5
    Digitale Medien
    Digitale Medien
    Measurement of Bone Mineral Density in Mother–Daughter Pairs for Evaluating the Family Influence on Bone Mass Acquisition: A GRIO Survey (1998)
    Springer
    Osteoporosis international 8 (1998), S. 379-384 
    Details
    ISSN: 1433-2965
    Schlagwort(e): Key words:Bone mineral density – Dual-energy X-ray absorptiometry – Genetics – Heredity – Osteoporosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract: The relative influence of genetic and environmental determinants on bone mass is still unclear. Using an original multicentric mode of recruitment, based on absorptiometry current practice, the hypothesis of a familial predisposition to low bone mineral content was assessed. The study was based on dual-energy X-ray absorptiometry (DXA) measurements of lumbar and femoral neck bone mineral density (BMD), using daughters of women with a low BMD (case mothers). These BMD values were compared with those of control daughters of women with a normal BMD. Case mothers (n= 72) aged 54.3 ± 4.8 years were recruited on the basis of a questionnaire and a vertebral Z-score 〈 – 2 SD. Their healthy daughters of more than 20 years (n= 77) aged 28.2 ± 4.9 years had their vertebral and femoral BMD Z-score determined. The control groups were composed of mothers aged 54.1 ± 4.7 years, paired by age ± 2 years to the case mothers, and of their daughters of more than 20 years old, aged 27.7 ± 5.8 years. For daughters, a significant difference was found between the mean vertebral Z-scores (–0.82 ± 1.08 for cases and 0.01 ± 1.14 for controls, p 〈 0.0001). The difference was in the same direction but was not statistically significant for mean femoral Z-scores (–0.58 ± 1.15 for cases and –0.22 ± 1.33 for controls, p 〈0.073). These findings confirm the hypothesis of a familial predisposition to low BMD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001980050078
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  • 6
    Digitale Medien
    Digitale Medien
    Usefulness of Motor Functional MRI Correlated to Cortical Mapping in Rolandic Low-Grade Astrocytomas (1999)
    Springer
    Acta neurochirurgica 141 (1999), S. 71-79 
    Details
    ISSN: 0942-0940
    Schlagwort(e): Keywords: Functional magnetic resonance imaging; brain mapping; low grade astrocytoma.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary  The indications for surgery of slow growing tumours like low grade astrocytomas in eloquent areas are difficult. The timing and the benefit/risk ratio of the surgery must be evaluated, taking into account the potential post operative deficit. The purpose of this study was: a) to validate the data obtained with functional MRI (FMRI) by direct cortical stimulation in patients who are candidate for surgery; b) to demonstrate the usefulness of FMRI coupled with cortical brain mapping and 3D reconstructions of the surfaces of the brain in low grade astrocytoma. FMRI of the hand-motor cortex was performed in 8 patients with low grade astrocytomas. They subsenquently underwent direct cortical mapping to correlate the results of FMRI and resective surgery sparing the functional area. In the 8 cases, the results of direct cortical mapping in the precentral region matched accurately those obtained from FMRI. When surgical resection of low grade astrocytoma in the motor areas is considered, FMRI used with intra-operative cortical mapping can help the surgeon to spare functional areas during tumour removal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007010050268
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  • 7
    Digitale Medien
    Digitale Medien
    Three-dimensional structure of scorpion toxins: Towards a new model of interaction with potassium channels (1999)
    Springer
    Perspectives in drug discovery and design 15-16 (1999), S. 41-60 
    Details
    ISSN: 1573-9023
    Schlagwort(e): dipole moment ; neurotoxin ; NMR ; potassium channel ; scorpion ; structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Scorpion venom contains various toxins which block ion-channels, responsible for either sodium, potassium, calcium or chloride membrane permeation. This review focuses on the three-dimensional structure of scorpion toxins specific for potassium channels, and on their structure–activity relationships. The overall fold of all these toxins is similar, despite their various specificities towards different types of potassium channels. Fine studies of the influence of punctual mutations of both toxins and channels have converged on a precise description of the scorpion toxins functional maps. From this knowledge, it now becomes possible to predict the specificity of a newly described scorpion toxin. The way is thus now open that leads to the design of new potent synthetic potassium channel blockers which in turn could be used as therapeutic drugs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1017070801207
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