Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Al toxicity-tolerance  (2)
  • Broadband ultrasonic attenuation  (2)
  • 1
    ISSN: 1433-2965
    Keywords: Bone mineral measurements ; Broadband ultrasonic attenuation ; Ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a study of broadband ultrasonic attenuation (BUA) in the calcaneus in 248 women. Measurements were performed with a Walker-Sonix UBA-575 ultrasonic bone analyser. The populations studied were 15 healthy young volunteers (group 1, mean age 26 years), 200 healthy pre- and postmenopausal women (group 2, mean age 53 years) and 33 osteoporotic women with vertebral crush fractures (group 3, mean age 66 years). Subjects in group 1 each had 10 repeated measurements of their right heel. Duplicate BUA measurements in the right heel were performed in 96 subjects and bilateral scans in a further 87 women in group 2. The remaining 17 subjects in group 2 and those in group 3 had a single scan of the right heel. All women in groups 2 and 3 had dual X-ray absorptiometry (DXA) scans of the lumbar spine and femoral neck. The precision study on the women in group 1 gave a root mean square (RMS) coefficient of variation (CV) of 4.2%. Individual CV results showed statistically significant differences (range 1.3%–7.6%). Duplicate scans in subjects in group 2 gave a RMS CV of 4.6% while the bilateral measurements showed no significant difference between the two heels. Linear regression analysis gave the following relationship between BUA and age: BUA=87.1−0.76 (Age −40) dB/MHz (r=−0.31,p〈0.001, SEE=14.0 dB/MHz). Multivariate regression analysis showed that, in addition to age, years since the menopause was also a significant factor in predicting BUA. In the first 5 years following the menopause BUA decreased by 2.5%/year, while in the next 5 years the decrease fell to 0.5%/year. The BUA measurements in the osteoporotic subjects in group 3 gave a mean T-score of −2.1 compared with 66 premenopausal normal women and a mean Z-score of −1.0 compared with 27 age-matched elderly normal women in group 2. In comparison the lumbar spine DXA measurements for the same women gave a mean T-score of −3.2 and a mean Z-score of −1.8. DXA therefore gave substantially better discrimination between osteoporotic and normal subjects than the BUA measurements.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0827
    Keywords: Bone mineral measurements ; Broadband ultrasonic attenuation ; Calcaneus ; Ultrasonic velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Measurements of broadband ultrasonic attenuation (BUA) and velocity of ultrasound through the heel (heel velocity, HV) were performed with a Contact Ultrasonic Bone Analyzer (CUBA-Research model) in 229 women. The subjects consisted of 16 healthy young volunteers (Group 1, mean age 26 years), 170 healthy pre- and postmenopausal women (Group 2, mean age 53 years), and 43 osteoporotic women with radiographically defined vertebral crush fracture (Group 3, mean age 66 years). Subjects in Group 1 had 10 repeated measurements in a study of short-term precision. Women in Groups 2 and 3 also had dual X-ray absorptiometry (DXA) scans to measure lumbar spine and femoral neck bone mineral density (BMD). The BUA and HV measurements for all 229 women showed a significant correlation (r = 0.75,P 〈 0.001). The precision study on the subjects in Group 1 gave a root mean square coefficient of variation of 6.3% for BUA and 1.04% for HV. Linear regression analysis gave the following relationship between BUA and age for the 170 normal women in Group 2: BUA = 83.6 − 0.86 (age 40) dB/MHz (r = −0.31,P 〈 0.001, SEE = 16.3 dB/MHz). The relationship between HV and age was as follows: HV = 1614 − 2.3 (age 40) m/s (r = −0.33,P 〈 0.001, SEE = 42 m/s). Multivariate regression analysis showed that in addition to age, years since the menopause was also a significant factor in determining both BUA and HV. In the first 5 years following the menopause, BUA and HV decreased by 2.2% and 0.3%/year, respectively, whereas in the next 10 years the rates of decrease fell to 0.5% and 0.03%/year. The BUA and HV measurements on the 43 osteoporotic subjects in Group 3 gave mean T-scores of −2.1 and −1.9 compared with 59 premenopausal women, and mean Z-scores of −1.3 and −0.9 compared with 26 age-matched normal women in Group 2, respectively. In comparison, the lumbar spine and femoral neck DXA measurements in the same subjects gave mean T-scores of −2.9 and −2.1 and mean Z-scores of −1.7 and −1.0, respectively. Lumbar spine BMD gave the best discrimination between women with osteoporotic vertebral fractures and normal subjects. However, the difference between the lumbar spine and BUA Z-scores was not statistically significant. Femoral neck BMD was equivalent to the ultrasound parameters in T-score and Z-score values.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 96 (1986), S. 259-272 
    ISSN: 1573-5036
    Keywords: Acidity ; Al toxicity-tolerance ; H-toxicity-tolerance ; Pacific Northwest ; Picea sitchensis ; Pseudotsuga menziesii ; Solution culture ; Thuja plicata ; Tsuga heterophylla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seedlings of four Pacific Northwest conifer species; Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla), western redcedar (Thuja plicata), and Sitka spruce (Picea sitchensis) were grown in solution culture at six levels of aluminium concentration (0, 10, 25, 50, 75 and 100 ppm Al). The pH of these nutrient solutions was adjusted to be equivalent with that level induced by hydrolysis of the highest Al treatment (pH 3.5 of the 100 ppmAl treatment). Divalent cation concentration in the roots of all four species decreased as Al activity increased. Potassium was the only nutrient that exhibited increased tissue concentrations as Al activity increased. Phosphorus and N in the seedlings had complex responses to increasing Al. Western hemlock and Sitka spruce root length was the main growth property found to be significantly affected by Al activity in the solutions. Increasing Al concentrations in these acid nutrient solutions did not significantly affect biomass growth of any of the four species. Western hemlock and western redcedar were especially tolerant of these acid-Al conditions. These results have been related to western hemlock's low tissue requirements of Ca and Mg and western redcedar's ability to accumulate high tissue levels of Ca even in the presence of excess H and Al-cations.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 96 (1986), S. 239-257 
    ISSN: 1573-5036
    Keywords: Acidity ; Al toxicity-tolerance ; H toxicity-tolerance ; Pacific Northwest ; Pseudotsuga menziesii ; Solution culture ; Thuja plicata ; Tsuga heterophylla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seedlings of three Pacific northwest conifer species: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western redcedar (Thuja plicata Donn) were grown in acid nutrient solutions with and without aluminium present. The acid treatments were paired so as to differentiate the effects of aluminium from the hydrogen ion concentration that a specific level of Al-cations induces via hydrolysis reactions. Relative to agronomic plants, all the conifers were found tolerant of the acid solutions and high levels of aluminium. Species differed in their relative tolerance to H and Al-cations. Douglas-fir and western redcedar both displayed similar or better growth in nutrient containing 175 ppm Al than in solutions at the same pH (3.0) without aluminium. In contrast to the other species, western hemlock survived and thrived in acid solution of pH 3 while the presence of Al in acid solution adversely affected seedling root growth and tissue divalent cation concentrations, especially calcium and magnesium. Therefore, the ability of western hemlock to grow in acid conditions is postulated to be related to this species' physiological tolerance of excess H-cations in solution and low tissue requirements of Ca and Mg. This tolerance of H-cation concentrations found for western hemlock meant that the specific effects of high Al concentrations in solution could be differentiated in hemoock seedling growth and nutrition from those effects caused by increased H-concentration due to Al-hydrolysis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...