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  • Biochemistry  (1)
  • Key words: Broadband ultrasound attenuation — Contact ultrasound bone analyzer — Bone mineral density — Dual energy X-ray absorptiometry — Chronic rheumatic diseases.  (1)
  • Phenylglyoxylic acid  (1)
  • m-Methylhippuric acid  (1)
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Material
Years
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Comparison of Quantitative Calcaneal Ultrasound and Dual Energy X-ray Absorptiometry in the Evaluation of Osteoporotic Risk in Children with Chronic Rheumatic Diseases (2000)
    Springer
    Calcified tissue international 67 (2000), S. 19-23 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Broadband ultrasound attenuation — Contact ultrasound bone analyzer — Bone mineral density — Dual energy X-ray absorptiometry — Chronic rheumatic diseases.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Osteoporosis is a common complication in children with chronic rheumatic diseases (CRD). Although dual energy X-ray absorptiometry (DXA) is increasingly being used to determine bone mineral density (BMD) in children, it exposes the subject to ionizing radiation and does not provide a measure of true bone density; in fact, in growing bones the increase in BMD is mainly caused by the increase in bone size. In recent years, quantitative ultrasound techniques (QUS) have been used in radiation-free assessment of bone density and ``bone quality'' by measurement of the ultrasound waves attenuation by bone (BUA). In the present study we made a direct comparison of BUA in the calcaneum, determined by the pediatric contact ultrasound bone analyzer (CUBA) with lumbar BMD measured by DXA, in a group of 6–18-year-old patients with CRD. The study group consisted of 53 patients affected with juvenile rheumatoid arthritis (n = 29), systemic lupus erythematosus (n = 13), and juvenile dermatomyositis (n = 11). Mean age was 13.02 ± 2.69 years. In 22 patients (19 girls, 3 boys) both DXA and CUBA were repeated after 1 year in order to assess the mean percentage rate of BMD and BUA change over this time. Both lumbar spine BMD and calcaneal BUA measurements were lower in the CRD patients compared with a control group (P 〈 0.001). Calcaneal BUA was significantly correlated (r = 0.83, P 〈 0.001) with lumbar spine BMD. Age and sex correction (Z-score) did not change the relationship between BUA and BMD (r = 0.80, P 〈 0.001). A significant correlation between the mean percentage of variation (Δ%) of BMD and BUA (r = 0.76, P 〈 0.001) was also demonstrated in the 22 patients who were evaluated prospectively. Portability, ease of use, lower cost, and absence of radiation make CUBA a promising means of evaluating BMD in children.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00223001090
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  • 2
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatography for the quantitative determination of the urinary metabolites of toluene, xylene, and styrene (1982)
    Springer
    International archives of occupational and environmental health 50 (1982), S. 25-31 
    Details
    ISSN: 1432-1246
    Keywords: Toluene ; Xylene ; Styrene ; Hippuric acid ; m-Methylhippuric acid ; Phenylglyoxylic acid ; Mandelic acid ; Urinary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new high-pressure liquid chromatography (HPLC) method for simultaneous quantitative determination of the urinary metabolites of toluene, m-xylene, and styrene (hippuric acid, m-methylhippuric acid, phenylglyoxylic acid, mandelic acid) is described. The extraction procedure was performed on acidified urines, after addition of 4-hydroxybenzoic acid as internal standard, using a butylchloride/isopropanol mixture and drying 0.5 ml of the organic layer under nitrogen flow. The residue obtained was dissolved in 0.1 ml water/acetonitrile and 5 μl were injected into an HPLC apparatus equipped with a 0.26 × 25 cm HC ODS SIL X column. Absorbance measures were performed at 225 nm throughout the investigation. All metabolites were clearly separated in a short time (12 min) and the amounts of other urinary compounds affecting the analysis were so small that the measurement of low concentrations of the urinary metabolites could be easily performed. Linear calibration curves were obtained from 0.1 to 3 mg/ml and a correlation coefficient greater than 0.99 was found between concentrations of the standards and areas of the peaks. Statistical analysis confirms that this method, which has a high reproducibility, is simple, reliable, and useful for the biologic monitoring of industrial exposure to aromatic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432491
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Electronic optical activity of (-)-α-phellandrene (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 4 (1983), S. 260-266 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Molecular orbital computations on the sign and magnitude of the Cotton effect of (-)-α-phellandrene (a conjugated diene) and the separate twisted butadiene chromophore were performed using configuration interaction (CI) and the random phase approximation (RPA) methods with a standard minimal basis set of STO/3G orbitals. The relative contributions to the rotatory strength of (-)-α-phellandrene which arise from a twist in the diene unit, the allylic axial bond, and nonplanarity of either one or both of the C=C double bonds were determined by examining various molecular geometries. This theoretical study confirms that the allylic axial substituent/bond provides the largest contribution to the longwavelength Cotton effect. It is found that the rotatory strength arising from distortion of the planar geometry of the double bonds tends to cancel the rotatory strength arising from the sense of twist of the diene unit. The computed energies suggest that molecular geometries where the trisubstituted bond is kept planar, and where twisting is allowed about the cis double bond, may be favored over geometries where torsion is allowed about both double bonds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540040217
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    Paper (German National Licenses)
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