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  • Cell nuclei  (1)
  • Key words: Tobacco — Smoking — Bone remodeling.  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Effects of Nicotine on Bone and Calciotropic Hormones in Growing Female Rats (2000)
    Springer
    Calcified tissue international 67 (2000), S. 68-74 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Tobacco — Smoking — Bone remodeling.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Limited research in young adults and immature animals suggests a detrimental effect of tobacco on bone during growth. This study investigated the effects of nicotine, the major alkaloid component of tobacco, on calciotropic hormone concentrations and bone status in growing female rats. One-month-old animals received either saline (n = 10), nicotine at 3.0 mg/kg/day (n = 10), or nicotine at 4.5 mg/kg/day (n = 10) administered subcutaneously via osmotic minipumps for either 2 or 3 months. Sera, femora, tibiae, and lumbar vertebrae (3–5) were collected at necropsy. The concentrations of serum calcium, phosphorus, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, calcitonin, and insulin-like growth factor-I were determined. Bone variables evaluated included mineral content and density (vertebrae and femora), cancellous and cortical histomorphometry (tibiae), and bone strength (vertebrae and femora). Statistically significant differences in serum mineral and hormone concentrations were not associated with nicotine dose or exposure time. No significant nicotine treatment effects were detected for bone mineral content and density, bone histomorphometry, or bone strength. We conclude that nicotine treatment for 2 or 3 months at serum concentrations in the upper range of those found in smokers has no detrimental effect on bone mass, volume, or strength in the growing rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00223001099
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in the Organization of the Smooth Muscle Cells in Rat Vein Grafts (1998)
    Springer
    Annals of biomedical engineering 26 (1998), S. 86-95 
    Details
    ISSN: 1573-9686
    Keywords: Vascular remodeling ; Cell nuclei ; Actin filaments ; Smooth muscle ; Vein ; Grafts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Mechanical tensile stress in vein grafts increases suddenly under the influence of arterial blood pressure. In this study, we examined the influence of increased tensile stress on the organization of the smooth muscle cells (SMCs) in the neointima and media of the rat vein grafts. An autogenous jugular vein was grafted into the abdominal aorta of the rat, and changes in the organization of the vein graft SMCs were studied by observing the distribution of SMC actin filaments and nuclei at 3 min and 1, 5, 10, and 30 days after surgery. In a normal jugular vein, the average wall circumferential tensile stress was ~ 3 kPa at an internal pressure of 3 mm Hg. The SMCs, that contained long, slender actin filamentous bundles, were oriented mainly in the circumferential direction of the vessel, and constituted a 2- to 3-cell-thick medial layer underneath the endothelium. In a vein graft, the wall circumferential tensile stress suddenly increased by ~ 140 times compared with the control level. In response to this suddenly increased stress, the SMC layer was stretched into a structure with scattered pores and disrupted SMC actin filamentous bundles within 3 min. This initial change was followed by a rapid reduction in the density of the SMC nuclei and actin filaments within 1 day and progressive SMC proliferation, that was associated with medial thickening and a change in the SMC orientation from 5 to 30 days. Further studies showed that a local inflation of normal jugular veins to 120 mm Hg for 3 min induced a similar change as found in the vein grafts, whereas the organization of the SMCs was not significantly changed in vein-vein grafts, that did not experience a change in tensile stress. These results suggested that increased tensile stress contributed to the initial damage of the SMCs and played a role in the regulation of medial SMC remodeling in vein grafts. © 1998 Biomedical Engineering Society. PAC98: 8722-q, 8745-k
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.52
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