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  • 1
    Electronic Resource
    Electronic Resource
    Central melatonin receptors: Implications for a mode of action (1989)
    Springer
    Cellular and molecular life sciences 45 (1989), S. 955-965 
    Details
    ISSN: 1420-9071
    Keywords: Melatonin ; receptors ; in vitro ; autoradiography ; brain ; pituitary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The influence of melatonin on circadian and photoperiodic functions in numerous species is well documented. It is known that the effect of melatonin on circadian rhythmicity is mediated via the suprachiasmatic nucleus (SCN), the biological clock of the brain. It is not known however where the photoperiodic effects of melatonin are mediated. Evidence from brain lesioning and melatonin implant studies point to a site in or near the medial hypothalamus. In contrast to these studies, melatonin receptors have been reported in widespread areas of the brain, the pituitary and in peripheral tissues. The characteristics of the reported melatonin receptors vary widely between studies and consequently no definitive description of a physiologically relevant melatonin receptor has received universal recognition. This review marshals recent evidence for the localization and characterization of the melatonin receptor and discusses these findings in the context of the known effects of the hormone in different species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01953053
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  • 2
    Electronic Resource
    Electronic Resource
    Device quality Hg1−xCdxTe material by low-temperature precracking metalorganic chemical vapor deposition (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2021-2022 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report properties of device quality Hg1−xCdxTe grown by a precracking metalorganic chemical vapor deposition technique. The refinement of the low-temperature growth process and a higher purity metalorganic mercury source enable us to obtain material which has a carrier concentration of 2×1015 cm−3 and mobility as high as 330 000 cm2/V s. Infrared transmission spectra and the photoluminescence measurements obtained from this material will be presented. With further development in the synthetic route of the metalorganic mercury source, further improvement in the purity of the Hg1−xCdxTe is possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101179
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  • 3
    Electronic Resource
    Electronic Resource
    Stimulation of Melatonin Synthesis in Ovine Pineals In Vitro (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 50 (1988), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Static and superfused pineal slices (750 μm) have been used to study the control of melatonin synthesis by ovine pineals. Static incubates show a time-dependent accumulation of melatonin in the medium; this is significantly increased by stimulation with norepinephrine (NE) (10−5M), reaching 300% above control levels after 4 h. Perifused pineal slices show a rapid rise in melatonin release within 12–18 min in response to NE stimulation. This reaches a 3.5–4.5-fold increase in melatonin released within 30 min. Withdrawal of NE is associated with a rapid return to prestimulated levels within 12–18 min. These time-course characteristics compare favorably to those changes seen in vivo. The formation of [14C]melatonin from [14C]-tryptophan shows a linear increase with time. In the presence of NE (10−5M), the rate of synthesis is increased, albeit after an initial time lag of at least 30 min. The latter may reflect an N-acetyltransferase-independent mechanism of synthesis and release. In static incubations, propranolol (10−5M) inhibited NE-induced melatonin production by about 60%. but prazosin (10−5M) had no effect. As dibutyryl cyclic AMP (10−3M) stimulated melatonin production, it is concluded that β-receptors are of primary importance to the control of melatonin production, as in the rat. The role of α1-receptors is less clear, but the stimulatory action of phorbol 12-myristate 13-acetate on melatonin release implicates a receptor linked to phosphatidylinositol turnover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1988.tb13232.x
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  • 4
    Electronic Resource
    Electronic Resource
    Plasma-enhanced chemical vapor deposited HgTe-CdTe epitaxial superlattices (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1329-1331 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For the first time, small-period epitaxial superlattices were grown using plasma-enhanced chemical vapor deposition. The superlattices were periods of HgTe-CdTe grown on CdTe substrates at 150 °C using dimethylcadmium, dimethylmercury, and dimethyltelluride. Cross-section transmission electron microscopy shows that layers as thin as 80 A(ring) were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100706
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  • 5
    Electronic Resource
    Electronic Resource
    Occlusion of the Melatonin-Free Interval Blocks the Short Day Gonadal Response of the Male Syrian Hamster to Programmed Melatonin Infusions of Necessary Duration and Amplitude (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 3 (1991), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Photoperiodic control of the neuroendocrine axis is mediated by changes in the duration of the nocturnal melatonin signal. This study tested the hypothesis that reading of the signal depends upon the presence of a period free of melatonin between successive signals. Adult male Syrian hamsters were pinealectomized and received chronic subcutaneous infusions of melatonin or saline for 6 weeks. Animals which received saline had large testes. Those which received a single daily infusion which lasted for 10 h (50 ng/h) followed by 14 h without infusion underwent gonadal atrophy. Other animals received a compound melatonin signal in which the melatonin-free interval was occluded by a continuous infusion (25 ng/h). Superimposed upon this was a 10 h phasic increase in infusion rate such that the maximum rate of infusion was equivalent to that observed in controls (25 ng/h increase, 50 ng/h peak rate), or the increase in rate over the baseline was the same as in controls (50 ng/h increase, 75 ng/h peak rate). In neither group did the animals undergo gonadal regression. Analysis of iodomelatonin binding sites by in vitro autoradiography failed to reveal any systematic difference between animals which did and did not respond to melatonin and so the absence of a response could not be attributed to loss of receptors. These data demonstrate that the photoperiodic system cannot identify the melatonin signal solely upon the features of nocturnal peak height or amplitude of the peak over baseline. They are consistent with the hypothesis that the melatonin-free interval plays a significant role in photoperiodic time measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2826.1991.tb00283.x
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  • 6
    Electronic Resource
    Electronic Resource
    Melatonin Receptor Sites in the Syrian Hamster Brain and Pituitary. Localization and Characterization Using [125|]lodomelatonin (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 1 (1989), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A high-affinity, discretely localized melatonin receptor has been characterized and mapped within the brain and pituitary of the Syrian hamster using the high specific activity ligand [125|]iodomelatonin and a combination of in vitro autoradiography and membrane homogenate receptor assays. Specific binding of radioligand was found in regions of the epithalamus and hypothalamus in the brain and the pars tuberalis of the pituitary. Excitatory amino-acid lesions destroyed [125|]iodomelatonin binding within the brain, demonstrating that binding sites are located on neurons. Analysis of [125|]iodomelatonin binding to membrane homogenates of the pars tuberalis revealed a linear relationship between specific ligand binding and the amount of tissue. The time-course of specific binding at 37°C reached equilibrium after 30 min and remained stable thereafter. The addition of increasing concentrations of [125|]iodomelatonin alone and in the presence of 1 μM melatonin showed that specific binding reached equilibrium at 80 to 100 pM. Analysis of the saturation isotherm using a one-site binding model was consistent with a single receptor site with a Kd of 29.3 (±5.9 SEM) pM and Bmax of 2.54 (±0.19 SEM) fmol/mg protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2826.1989.tb00122.x
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  • 7
    Electronic Resource
    Electronic Resource
    Melatonin Receptors are Present in Non-Optic Regions of the Brain of a Deep-Sea Fish Living in the Absence of Solar Light (1996)
    Oxford : Blackwell Science Ltd.
    Journal of neuroendocrinology 8 (1996), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pineal melatonin hormonally transduces photoperiod to influence daily and seasonal cycles in most vertebrates (1, 2). Evidence of melatonin receptors throughout the brain of several fish species (3–5), particularly in retinorecipient structures, also indicates a role in visual processing. Despite the absence of solar light many deep-sea organisms show seasonality (6–8). The presence of central melatonin receptors was investigated by quantitative in vitro autoradiography in the deep-sea fish Coryphaenoides (Nematonurus) armatus. Specific, time-dependent, saturable, high affinity and guanine nucleotide sensitive, 2-[125I]iodomelatonin binding was found over the mid-brain tegmentum and hindbrain. Competing ligand potency was iodomelatonin 〉 melatonin 5-HT. Although C.(N.) armatus has well developed eyes no 2-[125I]iodomelatonin binding occurred in optic tectum, cerebellum or hypothalamus. Thus melatonin involvement in processing of visual information and control of seasonal physiology via hypothalamic areas appears to be absent in this species. The presence of central G-protein coupled receptors indicates a function for melatonin unrelated to solar light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2826.1996.tb00702.x
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  • 8
    Electronic Resource
    Electronic Resource
    Melatonin Receptors in the Brain and Pituitary Gland of Hypothalamo-Pituitary Disconnected Soay Rams (1997)
    Oxford, UK : Blackwell Science Ltd.
    Journal of neuroendocrinology 9 (1997), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In Soay rams in which the pituitary gland has been surgically separated from the hypothalamus, blood prolactin concentrations vary in response to changes in photoperiod and the administration of melatonin, as in intact animals, providing evidence that melatonin acts within the pituitary gland to control prolactin secretion. In this study the presence of potentially functional melatonin receptors in the pars tuberalis and zona tuberalis (PT/ZT) of hypothalamo-pituitary disconnected (HPD) Soay rams is confirmed using both in vitro autoradiography with the ligand 2-(125I)- iodomelatonin and in situ hybridization for the melatonin receptor. There was no effect of the HPD operation on the pattern and quantity of 2-(125I)iodomelatonin binding in the brain demonstrating that this binding is independent of hypothalamic regulation. The possibility that melatonin may control prolactin secretion directly via specific receptors on lactotrophs was investigated using dual in situ hybridization with a (35S) labelled probe for the ovine melatonin receptor (Mel1ab) and a Digoxigenin labelled probe for ovine prolactin. Melatonin receptor gene expression was observed in the PT/ZT in both intact and HPD rams, however, there was no colocalization with prolactin gene expression; only in the ZT was there a close association between cells expressing the melatonin receptor and lactotrophs. The results provide strong support for the view that melatonin acts via the PT/ZT to mediate the effects of photoperiod on the seasonal cycle in prolactin secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2826.1997.00625.x
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  • 9
    Electronic Resource
    Electronic Resource
    Outbreaks of an EHNV-like iridovirus in cultured rainbow trout, Salmo gairdneri Richardson, in Australia (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 11 (1988), S. 0 
    Details
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2761.1988.tb00527.x
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  • 10
    Electronic Resource
    Electronic Resource
    Silicon epitaxy by hot wall plasma enhanced chemical vapor deposition (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6424-6427 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hot wall plasma enhanced chemical vapor deposition is examined for epitaxial silicon growth for advanced devices. The reactor has a load lock and can provide an in situ plasma clean of the wafers before deposition. At 800 °C, layers of good quality are obtainable at growth rates of 1.4 μm/h. Defect densities for the layers are low. Concentrations of carbon and oxygen at the epilayer-substrate interface are comparable to those for more elaborate cleaning processes. Although the wafers are directly exposed to the plasma during the cleaning and the deposition, no additional defects caused by the plasma were detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346864
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