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  • Life and Medical Sciences  (3)
  • steroid biosynthesis  (2)
  • α2-Adrenoceptors  (2)
  • Basal ganglia  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Agmatine recognizes α2-adrenoceptor binding sites but neither activates nor inhibits α2-adrenoceptors (1994)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1994), S. 10-16 
    Details
    ISSN: 1432-1912
    Keywords: Key words Agmatine ; α2-Adrenoceptor binding sites ; α2-Adrenoceptors ; Clonidine-displacing substance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has been suggested that agmatine (decarboxylated arginine) is an endogenous clonidine-displacing substance (CDS) which recognizes α2-adrenoceptor and non-adrenoceptor, imidazoline binding sites. We have examined the effect of agmatine at α2-adrenoceptor binding sites and pre- and postjunctional α2-adrenoceptors. Agmatine produced a concentration-dependent inhibition of 1 nmol/l 3H-clonidine binding to both rat (pKi–5.10±0.05) and bovine (pKi–4.77±0.38) cerebral cortex membranes. However, agmatine (0.1–100 μM) failed to activate pre-junctional α2-adrenoceptors regulating transmitter release in the guinea-pig isolated ileum and rat isolated vas deferens, nor did it activate postjunctional α2-adrenoceptors of the porcine isolated palmar lateral vein which mediate contraction or inhibition of forskolin-stimulated cyclic AMP formation. High concentrations of agmatine (10–30-fold the pKi at α2-adrenoceptor binding sites) failed to influence α2-adrenoceptor activation by either clonidine or UK-14304 (5-bromo-6-[2-imidazolin-2-ylamino]-quinoxaline bitartrate) in any of the peripheral preparations examined. Moreover, even in a preparation where an interaction with α2-adrenoceptor binding sites on cell membranes can be demonstrated, the rat cerebral cortex, agmatine failed to inhibit forskolin-stimulated cyclic AMP in the intact tissue or affect the inhibition produced by the selective α2-adrenoceptor agonist UK-14304. Agmatine was also devoid of agonist activity in two preparations, the rat isolated thoracic aorta and the rat isolated gastric fundus, in which CDS has been reported to produce non-adrenoceptor effects. Thus, we have confirmed that agmatine recognizes α2-adrenoceptor binding sites and, therefore, is a CDS. However, since agmatine is devoid of pharmacological activity at either peripheral or central α2-adrenoceptors it can not account for earlier reports suggesting that brain-derived CDS can activate α2-adrenoceptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169058
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Microstimulation of movements from cerebellar-receiving, but not pallidal-receiving areas of the macaque thalamus under ketamine anaesthesia (1998)
    Springer
    Experimental brain research 123 (1998), S. 387-396 
    Details
    ISSN: 1432-1106
    Keywords: Key words Thalamus ; Basal ganglia ; Cerebellum ; Electrical stimulation ; Movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The motor thalamic areas receiving input from the globus pallidus (VA) and the cerebellar nuclei (VL) appear to have different roles in the generation and guidance of movements. In order to further test these differences, we used electrical stimulation to map the ventro-anterior and ventro-lateral nuclei of the thalamus in three ketamine anaesthetised monkeys. Movements were readily evoked from VL at currents of down to 10 μA. The movements were typically multi-joint, and stimulation could evoke arm and trunk or arm and facial movement at the same current threshold. Evoked arm movements often involved multiple joints, with or without finger movements. Facial movements included the lips, tongue, jaw, eyebrows and, occasionally, the eyes. The thalamic map was topographic, but complex with at least two separate regions related to arm movement. Very few sites within the VA could stimulate movement, even at high currents. We therefore suggest that the cerebellar projections to motor regions of the cortex, which pass through the VL thalamic nuclei, have a different relationship and are closer to movement execution than the projections from basal ganglia via the ventro-anterior nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050584
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  • 3
    Electronic Resource
    Electronic Resource
    Agmatine recognizes α2-adrenoceptor binding sites but neither activates nor inhibits α2-adrenoceptors (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 10-16 
    Details
    ISSN: 1432-1912
    Keywords: Agmatine ; α2-Adrenoceptor binding sites ; α2-Adrenoceptors ; Clonidine-displacing substance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has been suggested that agmatine (decarboxylated arginine) is an endogenous clonidine-displacing substance (CDS) which recognizes α2-adrenoceptor and non-adrenoceptor, imidazoline binding sites. We have examined the effect of agmatine at α2-adrenoceptor binding sites and pre- and postjunctional α2-adrenoceptors. Agmatine produced a concentration-dependent inhibition of 1 nmol/l 3H-clonidine binding to both rat (pKi–5.10+-0.05) and bovine (pKi–4.77+-0.38) cerebral cortex membranes. However, agmatine (0.1–100 μM) failed to activate pre-junctional α2-adrenoceptors regulating transmitter release in the guinea-pig isolated ileum and rat isolated vas deferens, nor did it activate post-junctional α2-adrenoceptors of the porcine isolated palmar lateral vein which mediate contraction or inhibition of forskolin-stimulated cyclic AMP formation. High concentrations of agmatine (10–30-fold the pKi at α2-adrenoceptor binding sites) failed to influence α2-adrenoceptor activation by either clonidine or UK-14304 (5-bromo-6-[2-imidazolin-2-ylamino]-quinoxaline bitartrate) in any of the peripheral preparations examined. Moreover, even in a preparation where an interaction with α2-adrenoceptor binding sites on cell membranes can be demonstrated, the rat cerebral cortex, agmatine failed to inhibit forskolin-stimulated cyclic AMP in the intact tissue or affect the inhibition produced by the selective α2-adrenoceptor agonist UK-14304. Agmatine was also devoid of agonist activity in two preparations, the rat isolated thoracic aorta and the rat isolated gastric fundus, in which CDS has been reported to produce non-adrenoceptor effects. Thus, we have confirmed that agmatine recognizes α2-adrenoceptor binding sites and, therefore, is a CDS. However, since agmatine is devoid of pharmacological activity at either peripheral or central α2-adrenoceptors it can not account for earlier reports suggesting that brain-derived CDS can activate α2-adrenoceptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169058
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Tumour steroid hormone synthesis and estrogen receptor status in breast cancer patients (1981)
    Springer
    Breast cancer research and treatment 1 (1981), S. 263-266 
    Details
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogen receptors ; steroid biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The capacity of breast cancer to synthesise active androgens and estrogens has been related to estrogen receptor (ER) status in 79 postmenopausal patients with breast cancer. Although there was no quantitative relationship between levels of ER and steroid metabolism in ER positive tumours, there was (a) a positive correlation between estrogen synthesis and ER positivity and (b) increased androgen synthesis and ER negativity. This may imply an inherent difference in the handling of hormones in ER positive and negative tumours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01806266
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of drugs associated with hyperprolactinemia on plasma steroids and on steroid receptors and metabolism in human breast cancer (1983)
    Springer
    Breast cancer research and treatment 3 (1983), S. 331-338 
    Details
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogen receptor ; hyperprolactinemic drugs ; prolactin ; steroid biosynthesis ; steroid hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Certain commonly taken pharmaceutical preparations induce increased levels of plasma prolactin. The effects of these drugs on (a) tumor steroid receptors and metabolism, and (b) plasma hormones and hormone binding proteins have been studied in postmenopausal women with breast cancer. Two groups have been compared, 18 patients on drug treatment for at least 2 months and 15 subjects with no history of drug ingestion. Patients taking medication had significantly higher levels of plasma prolactin compared with control women. No significant difference was observed between the groups with regard to the plasma concentrations of dehydroepiandrosterone (DHA) and its sulphate (DHS), testosterone, estrone, estradiol-17β, sex hormone binding globulin (SHBG), and albumin. Similarly, no difference was observed between these two groups with regard to estrogen receptor (ER), progestogen receptor (PR), or androgen receptor (AR) levels in the tumors nor their ability to metabolize (7−3H) testosterone. It is considered that the ingestion of these drugs does not affect tumor mechanisms involving steroids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01807585
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Tumor necrosis factor-alpha induces vitamin D-1-hydroxylase activity in normal human alveolar macrophages (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 142 (1990), S. 652-656 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The induction of 1-hydroxylase in alveolar macrophages by tumor necrosis factor-alpha (TNF) was examined in view of recent evidence suggesting that local production of 1,25-(OH)2D3 may play a role in the regulation of immune functions. Incubation of pulmonary alveolar macrophages from normal human subjects with recombinant TNF caused a 2- to 10-fold increase in 25-hydroxyvitamin D3-1-hydroxylase activity. The dose-response curve was linear over the range 0.05 - 5.0 IU/ml, and no further increase was seen at higher concentrations. The increase in 1-hydroxylase activity was present after 12 h and reached a maximum after 3 days. The effect of TNF was inhibited in a dose-dependent manner by the presence of 1,25(OH)2D3 (10-10-10-8 M) in the incubation media for 5 days but was unaffected by 10-9 M 1,25(OH)2D3 after 12 h. The enhancement of macrophage 1-hydroxylase activity by TNF was comparable to that induced by gamma interferon (IFN) but the effects of maximal doses of both agents were not additive. The presence of antibody to TNF resulted in a 76% inhibition of TNF-induced 1-hydroxylase but had no significant effect on IFN-induced 1-hydroxylase activity.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041420327
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of ultraviolet irradiation on human skin-derived epidermal cells in vitro (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 157 (1993), S. 119-127 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of UVA, mixed UVA + B, and solar-simulated irradiation were examined in human keratinocytes and melanocytes cultured in vitro. Irradiation with UVA, UVA + 3, or the solar simulator caused a dose-dependent decrease in keratinocyte cell numbers and thymidine incorporation at 24 hours, with recovery after 48 and 72 hours. Divided dose regimens reduced the inhibitory effect of ultraviolet (UV) irradiation on cell numbers measured 24 hours after the last irradiation. Exposure to both UVA and UVA + B increased formation of cornified envelopes. Similar irradiance doses of UVA 80 minutes (1.12 J/cm2) and UVA + B 40 minutes (1.04 J/cm2) caused 2.4- and 3.3-fold increases in cornified envelope formation, respectively. With solar-simulated irradiation, the cornified envelope formation was increased by 3.5-fold after exposure of 8 minutes (2.6 J/cm2). Irradiation of melanocytes with UVA, UVA + B, or solar-simulated irradiation resulted in a dose-dependent decrease in melanocyte numbers after 24 hours compared with sham-irradiated controls. As a result of UV irradiation, tyrosinase activity of melanocytes measured at 24 hours was stimulated. UVA + B irradiation (1.04 J/cm2) increased tyrosinase activity approximately twofold, while UVA alone (1.1 J/cm2) increased tyrosinase four to sixfold and solar-simulated irradiation (1.3 J/cm2) increased tyrosinase approximately twofold compared to the control cells. Melanin content increased in cells after both UVA and mixed UVA + B irradiation. These results indicate that both UVA and mixed UVA + B irradiation had qualitatively similar effects on the proliferative and functional activity of skin-derived cells but that the type of irradiation and the dosage regimen affect the dose-response relationship. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041570116
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  • 8
    Electronic Resource
    Electronic Resource
    Intervertebral disc degeneration in adult mice with hereditary kyphoscoliosis (1984)
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 2 (1984), S. 333-338 
    Details
    ISSN: 0736-0266
    Keywords: Intervertebral disc ; Mouse mutant ; Kyphoscoliosis ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Breeding experiments confirmed that a hereditary form of kyphoscoliosis in the BDL strain mouse was due to an autosomal recessive gene (ky). Sagittal sections of whole vertebral columns from adult homozygous recessive mice (ky/ky) were examined histologically. All mice showed varying degrees of degenerative change in one or more intervertebral discs between the fifth cervical and the second thoracic vertebrae. The changes comprised loss of cells, loss of distinction between nucleus pulposus and annulus fibrosus, loss of characteristic ring-like structure in the annulus, and development of wedge-shaped discs. In most animals, degenerative disc substance protruded from the disc space, usually posteriorly, sometimes anteriorly, and occasionally through the vertebral end plate cartilage. Posterior protrusions impinged on the spinal cord.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jor.1100020405
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