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  • 1
    Electronic Resource
    Electronic Resource
    The Relation Between Trabecular Bone Strength and Bone Mineral Density Assessed by Dual Photon and Dual Energy X-Ray Absorptiometry in the Proximal Tibia (1996)
    Springer
    Calcified tissue international 59 (1996), S. 311-314 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Trabecular bone strength — Bone mineral density — Proximal tibia.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The feasibility of two noninvasive methods [dual photon absorptiometry (DPA) and dual energy X-ray absorptiometry (DXA)] for prediction in vivo of local variations of trabecular bone strength within the proximal tibia was evaluated in 14 cadaveric knees. Trabecular bone strength was measured using an osteopenetrometer and from destructive compression tests performed on bone cylinders, thus measuring the penetration strength and ultimate strength in the medial, lateral, and central part of the tibial bone specimens. Linear regression analysis showed significant relations between BMD measured by DPA (r2= 72%) or DXA (r2= 73%) and ultimate strength. Even closer relations between BMD (DPA: r2= 80%, DXA r2= 81%) and penetration strength of trabecular bone were found. We conclude that DPA and DXA are suitable methods for evaluation in vivo of local variations in trabecular bone strength within the proximal tibia, and could easily be performed preoperatively before insertion of total knee arthroplasty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900131
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dual Energy X-Ray Absorptiometry in Small Rats with Low Bone Mineral Density (2000)
    Springer
    Calcified tissue international 67 (2000), S. 455-459 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Small rats — Bone mineral density — Bone mineral content — Dual energy X-ray absorptiometry — Methodological evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The feasibility of dual energy X-ray absorptiometry (DXA) using the Norland XR-26 Mark II bone densitometer for measurements of bone mineral content (BMC) and bone mineral density (BMD) in small rats was evaluated. Thirty-two young, isogenic, Lewis rats (weights from 119 g to 227 g) were used; normal rats (n = 7) and rats with low BMD obtained from three different vitamin D-depleted models (n = 25). DXA measurements were performed using the special software for small animals. Duplicate scans of excised femurs performed at 2 mm/second (pixel size of 0.5 mm × 0.5 mm) were very precise measurements with a coefficient of variation (CV) below 1.6% in animals with normal BMD; in rats with low BMD, the CV was significantly higher (P= 0.02–0.04), 7.8% and 4.4% for BMC and BMD, respectively. Regression analysis demonstrated that these measurements were related to the ash weight (R2 〉 98.6%). The CV for measurements of the lumbar spine at 10 mm/second (pixel size 0.5 mm × 0.5 mm) was 2.6% and 2.2% for BMC and BMD, respectively in rats with normal BMD, and again higher (P= 0.03–0.14) in rats with low BMD, 7.3% and 4.7%, respectively, for BMC and BMD. Even though low CVs were obtained for total body duplicate scans (scan speed of 20 mm/second and a pixel size of 1.5 mm × 1.5 mm), the measurements were problematic for accuracy because of an overestimation of both BMC and the area of bone. Using these scan parameters the measurements of total body bone mineral could not be recommended in small rats with low BMD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002230001176
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of Vitamin D Metabolites and Analogs on Renal and Intestinal Calbindin-D in the Rat (1996)
    Springer
    Calcified tissue international 59 (1996), S. 371-376 
    Details
    ISSN: 1432-0827
    Keywords: Key words: 1,25-(OH)2D3— 24,25-(OH)2D3— Vitamin D3 analogs — Renal calbindin-D28k — Intestinal calbindin-D9k — Calcium.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The effects on renal and intestinal calbindin-D of vitamin D3 metabolites and synthetic 20-epi-vitamin D3 analogs with different calcemic actions were examined in Wistar rats. The compounds were administered intraperitoneally once daily for 5 days. The dosages of the metabolites were 1,25-(OH)2D3 0.01, 0.05, 0.1, and 0.4 μg/kg × d, 24,25-(OH)2D3 0.1, 1 and 10 μg/kg × d, and 25-(OH)D3 10 and 400 μg/kg × d. The dosage of the synthetic analogs were MC903 0.1, 10, and 100 μg/kg × d, EB1213 0.1 and 10 μg/kg × d, KH1060 0.1 and 0.4 μg/kg × d, and GS1725 0.01 and 0.1 μg/kg × d. Two control groups had either vehicle alone or no treatment. N= 8 in each group. 1,25-(OH)2D3 increased renal and intestinal calbindin-D levels, induced hypercalcemia, and suppressed plasma PTH and magnesium concentrations. 24,25-(OH)2D3 increased intestinal calbindin-D9k and plasma calcium, but had no effect on renal calbindin-D28k, plasma PTH, and magnesium. The dosage of 24,25-(OH)2D3 that was required to increase plasma calcium was larger than the dosage required to increase intestinal calbindin-D9k. 25-(OH)D3 did not change the calcium metabolic parameters. MC903, a low calcemic analog with a relative high affinity for the vitamin D receptor and a short half-life, increased renal calbindin-D28k without increasing ionized calcium or intestinal calbindin-D9k. EB1213, an analog with a reduced calcemic action and short half-life, increased renal calbindin-D28k and ionized calcium without increasing intestinal calbindin-D9k. The effect of the high calcemic vitamin D analogs KH1060 and GS1725 on calbindin-D was directly related to their calcemic activity. In conclusion, these results demonstrate that 24,25-(OH)2D3 increases intestinal calbindin-D9k, but has no effect on renal calbindin-D28k, that low calcemic analogs may increase renal calbindin-D28k without increasing intestinal calbindin-D9k, and that the effect of high calcemic analogs on calbindin-D is directly related to their calcemic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900142
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  • 4
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    A multicopy sRNA of Listeria monocytogenes regulates expression of the virulence adhesin LapB (2014)
    Oxford University Press
    Details
    Publication Date: 2014-08-15
    Description: The multicopy sRNA LhrC of the intracellular pathogen Listeria monocytogenes has been shown to be induced under infection-relevant conditions, but its physiological role and mechanism of action is not understood. In an attempt to pinpoint the exact terms of LhrC expression, cell envelope stress could be defined as a specific inducer of LhrC. In this process, the two-component system LisRK was shown to be indispensable for expression of all five copies of LhrC. lapB mRNA, encoding a cell wall associated protein that was recently identified as an important virulence factor, was disclosed to be directly bound by LhrC leading to an impediment of its translation. Although LhrC binds to Hfq, it does not require the RNA chaperone for stability or lapB mRNA interaction. The mechanism of LhrC- lapB mRNA binding was shown to involve three redundant CU-rich sites and a structural rearrangement in the sRNA. This study represents an extensive depiction of a so far uncharacterized multicopy sRNA and reveals interesting new aspects concerning its regulation, virulence association and mechanism of target binding.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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    PAPER CURRENT
  • 5
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    Physiological response to submaximal isometric contractions of the paravertebral muscles (1999)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: STUDY DESIGN: Brief (30-second) isometric trunk extensions at 5%, 20%, 40%, 60%, and 80% of maximal voluntary contraction (MVC) and 3 minutes of prolonged trunk extension (20% MVC) in erect position were studied in nine healthy male subjects. OBJECTIVES: To investigate the intercorrelation between intramuscular pressure and tissue oxygenation of the paravertebral muscles during submaximal isometric contractions and further, to evaluate paravertebral electromyogram and intramuscular pressure as indicators of force development. SUMMARY OF BACKGROUND DATA: Local physiologic responses to muscle contraction are incompletely understood. METHODS: Relative oxygenation was monitored with noninvasive near-infrared spectroscopy, intramuscular pressure was measured with a transducer-tipped catheter, and surface electromyogram was monitored at three recording sites. RESULTS: The root mean square amplitudes of the paravertebral electromyogram (L4, left and right; T12, right) and intramuscular pressure measured in the lumbar multifidus muscle at L4 increased with greater force development in a curvilinear manner. A significant decrease in the oxygenation of the lumbar paravertebral muscle in response to muscle contraction was found at an initial contraction level of 20% MVC. This corresponded to a paravertebral intramuscular pressure of 30-40 mm Hg. However, during prolonged trunk extension, no further decrease in tissue oxygenation was found compared with the tissue oxygenation level at the end of the brief contractions, indicating that homeostatic adjustments (mean blood pressure and heart rate) over time were sufficient to maintain paravertebral muscle oxygen levels. CONCLUSION: At a threshold intramuscular pressure of 30-40 mm Hg during muscle contraction, oxygenation in the paravertebral muscles is significantly reduced. The effect of further increase in intramuscular pressure on tissue oxygenation over time may be compensated for by an increase in blood pressure and heart rate. Surface electromyogram amplitudes and intramuscular pressure can be used as indicators of paravertebral muscle force.
    Keywords: Life Sciences (General)
    Type: Spine (ISSN 0362-2436); Volume 24; 22; 2332-8
    Format: text
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