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  • 1
    Digitale Medien
    Digitale Medien
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 54 (1992), S. 439-453 
    ISSN: 0066-4278
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Medizin , Biologie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1433-2965
    Schlagwort(e): Key words:Age-related – Australia – Epidemiology – Fracture rate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract: There is little population-based data concerning fracture rates in Australia. We ascertained all fractures occurring during 2 years in adults aged 35 years and over residing within a defined region (population 218 000), representative of the Australian population. The major strength of this study is the comprehensive ascertainment of fractures, which was ensured by regular searches of the only two radiologic providers in the Geelong Osteoporosis Study region. Nevertheless, vertebral fractures are likely to be underestimated since our ascertainment relied on a clinical indication for a medical imaging procedure. Among those aged 35 – 55 years, the fracture rate (persons per 10 000/year) in men was about double the rate in women (65 vs 35). The fracture rate was almost 7 times higher in women over 60 years versus women less than 55 years of age. In contrast, the fracture rate in men over 60 years was only 50% higher than in men less than 55 years of age (72 vs 104). Fracture rates in women and men were highest at the hip (28 and 10 respectively), spine (21 and 7), distal forearm (Colles’) (18 and 4) and humerus (11 and 3), and were 3–4 times higher in women than men. These fractures accounted for 63% of all fractures in women and 32% in men. By contrast, the rate of lower leg and ankle fractures was less than 10 per 10 000 in both women and men and did not increase to the same extent with age. Hip fracture rates appear high, particularly among the older age strata, compared with retrospective ascertainment in other populations. In Australia, as in many other countries, there is an increasing longevity of the population. The number of women aged 90 years and over increased by 32% and the number of men of this age increased by 48% in the 5 years between the Australian national census of 1991 and 1996. Given stable fracture rates, the substantial health burden imposed by age-related fractures, particularly hip fractures, will continue to escalate in both women and men.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-119X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The ultrastructure and immunocytochemistry of interstitial cells (ICs) in the canine proximal colon were investigated. Three types of ICs were found within the tunica muscularis. (1) ICs were located along the submucosal surface of the circular muscle (IC-SM). These cells shared many features of smooth muscle cells, including myosin thick filaments and immunoreactivity to smooth muscle gamma actin, myosin light chain, and calponin antibodies. IC-SM were clearly different from smooth muscle cells in that contractile filaments were less abundant and intermediate filaments consisted of vimentin instead of desmin. (2) ICs in the region of the myenteric plexus (IC-MY) were similar to IC-SM, but these cells had no thick filaments or immunoreactivity to smooth muscle gamma actin or calponin antibodies. (3) The fine structures and immunoreactivity of ICs within the muscle layers (IC-BU) were similar to IC-MY, but IC-BU lacked a definite basal lamina and membrane caveolae. IC-BU and IC-MY were both immunopositive for vimentin. Since all ICs were immunopositive for vimentin, vimentin antibodies may be a useful tool for distinguishing between ICs and smooth muscle cells. Each class of ICs was closely associated with nerve fibers, made specialized contacts with smooth muscle cells, and formed multicellular networks. A combination of ultrastructural and immunocytochemical techniques helps the identification and classification of ICs by revealing the fine structures and determining the “chemical coding” of each class of ICs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 432 (1996), S. 401-412 
    ISSN: 1432-2013
    Schlagwort(e): Key words Smooth muscle ; Delayed rectifier ; K+ channels ; Phosphorylation ; Gastrointestinal motility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We identified voltage-activated K+ channels in freshly dispersed smooth muscle cells from the circular layer of the canine colon in patch-clamp experiments using 200 nM charybdotoxin to suppress 270-pS Ca2+-activated K+ channels (BK channels). Three channel types were distinguished in symmetrical 140 mM KCl solutions: 19.5 ± 1.7 pS channels (KDR1), 90.6 ± 5.4 pS channels (KDR2) and 149 ± 4 pS intermediate-conductance Ca2+-activated K+ channels (IK channels). All three types showed an increase in open probability with membrane depolarization. Ensemble average current from KDR1 channels inactivated with a time constant of 1.7 ± 0.1 s at +60 mV test potential, while KDR2 and IK channels did not show inactivation. IK channels were activated by free cytoplasmic [Ca2+] (10−6 M) but were insensitive to 4-aminopyridine (4-AP, 10 mM) and intracellular tetraethylammonium (TEA, 1 mM). KDR1 channels were sensitive to 4-AP (10 mM) and intracellular TEA (1–10 mM) but not to Ca2+. KDR2 channels did not have a consistent pharmacological profile, suggesting that this class may be comprised of several subtypes. At +40 mV membrane potential, the catalytic subunit of protein kinase A (PKA) increased the open probability of KDR1 channels 3.4-fold and of KDR2 channels 3.9-fold, but had no effect on IK channels. In the absence of Mg-ATP, PKA did not affect channel open probabilities. At physiological membrane potentials (−60 mV) only openings of KDR1 channels could be induced by PKA, suggesting that these 4-AP-sensitive 20-pS K+ channels are primarily responsible for the cAMP-mediated hyperpolarization of colonic smooth muscle cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 421 (1992), S. 67-76 
    ISSN: 1432-2013
    Schlagwort(e): Ionic channels ; Potassium channels ; Smooth muscle ; Patch-clamp ; Vasodilators
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of cromakalim (BRL 34915) and its (−) optical isomer, lemakalim (BRL 38227) on the activity of 265-pS Ca2+-activated K+ channels (BK channels) were examined in cell-attached and inside-out patches from canine colonic myocytes. In cell-attached patches lemakalim increased the open probability (P o) of BK channels. Mean NP o, where N is the number of channels per patch, at + 50 mV increased from 0.08 to 0.26 (20 μM lemakalim). In inside-out patches, cromakalim and lemakalim increased channel NP o rapidly and reversibly. This increase in NP o was due to a shift in half-maximal activation. Glyburide (20 μM) prevented the increase in NP o caused by lemakalim in cell-attached patches and reversed the increase in NP o in inside-out patches. Under conditions where Ca2+-activated K+ channels were maximally activated, lemakalim failed to increase current or induce a second type of K+ channel activity. When tetraethylammonium (200 μM) was added to the pipette solution to block the BK channel half maximally, lemakalim also failed to induce a second type of channel. Adenosine triphosphate (1 or 2 mM) applied to the inner surface of inside-out patches had no effect on P o of BK channels. Finally, the effects of lemakalim on ensemble average currents, constructed from multiple openings of BK channels in cell-attached patches was found to successfully mimic the effects of the drug on whole-cell membrane currents. We conclude that cromakalim and lemakalim activate BK channels in canine colonic cells. Whether this action participates in the membrane hyperpolarization and the decrease in frequency and duration of slow waves produced by these compounds in intact colonic muscles remains to be investigated.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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