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  • 11
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Early life adversity is associated with an increased incidence of psychiatric illness in adulthood. Although the mechanisms underlying this association are unclear, one possible substrate is brain 5-hydroxytryptamine neurotransmission, which is reportedly abnormal in several psychiatric disorders. This study examined the effect of a rat model of early life adversity, early maternal separation, on 5-hydroxytryptamine neurotransmission in adulthood. In vitro electrophysiological experiments revealed that, in early maternal separation rats compared with controls, the sensitivity of α1-adrenoceptors on 5-hydroxytryptamine neurons in the dorsal raphe nucleus was significantly reduced, whilst the sensitivity of 5-hydroxytryptamine1A receptors showed a nonsignificant trend to reduction. In in vivo microdialysis experiments, the 5-hydroxytryptamine1A receptor agonist-induced suppression of 5-hydroxytryptamine release in the frontal cortex was reduced in early maternal separation animals, suggesting desensitization of 5-hydroxytryptamine1A autoreceptors. There was no increase in basal 5-hydroxytryptamine in the frontal cortex as measured by microdialysis and a nonsignificant trend towards increased basal firing activity of classical (non-bursting) 5-hydroxytryptamine neurons in the dorsal raphe nucleus measured by in vivo electrophysiology. Finally, early maternal separation failed to alter expression of messenger ribonucleic acids coding for 5-hydroxytryptamine1A or α1B receptors in the dorsal raphe nucleus as measured by in situ hybridization histochemistry, suggesting that functional changes in receptor sensitivity observed are not due to changes in receptor gene transcription. The findings demonstrate that early life adversity programs changes in sensitivity of the two principal regulators of 5-hydroxytryptamine neuronal activity. Similar effects in humans may contribute to the increased incidence of psychiatric illness in individuals exposed to early life adversity.
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  • 12
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The secretion of plasma melatonin exhibits a diurnal variation in the common marmoset (Callithrix jacchus jacchus) (n = 12) with mean values of 125.8 fmol/ml during darkness and below assay sensitivity (mean 70.5 fmol/ml) during the light period. Both melatonin secretion and the rest activity cycle appeared to be phase advanced with relation to the light dark cycle which is consistent with an endogenous circadian period (tau) of 〈 24 h in this species.
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  • 13
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Plasma melatonin was measured at the winter and summer solstices and the autumn and spring equinoxes in four mares held under natural conditions at 35°S. At all seasons the onset of the nightly elevated melatonin was coincident with or after the time of sunset and the melatonin offset after the time of sunrise. The duration of elevated melatonin was not different from the duration of natural scotophase for each season, with the duration of elevated melatonin longer in winter than the other seasons. Immediately following each 24 hr sampling two mares were resampled in acutely extended darkness to determine the melatonin profile of the endogenous rhythm of the circadian pacemaker, originating from the suprachiasmatic nuclei (SCN). At each season melatonin secretion commenced earlier and decreased later than that measured under the natural photoperiodic condition, suggesting that the expression of the melatonin rhythm is normally gated by natural environmental light both at dusk and dawn. The interval from the onset of melatonin measured under acutely extended darkness to the time of sunset was greater in the spring/ summer than the autumn/winter suggesting a possible alternating signal throughout the year. Thus the mare appears to exhibit a similar interaction between endogenous circadian rhythmic activity and the natural photoperiod as the ewe which may underlie the mechanism for timing reproductive activity through the year.
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  • 14
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 14 (1993), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.
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  • 15
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Marine aerosol contributes significantly to the global aerosol load and consequently has an important impact on both the Earth's albedo and climate. So far, much of the focus on marine aerosol has centred on the production of aerosol from sea-salt and non-sea-salt sulphates. Recent field ...
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  • 16
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 371 (1994), S. 563-564 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - We wish to report the successful transfer to mice of two genes, cysE and cysK, from Escherichia coli which encode the enzymes necessary for the assimilation of inorganic sulphide for the biosynthesis of the amino-acid cysteine1'2. These mice are able to synthesize cysteine when ...
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  • 17
    ISSN: 1279-8517
    Keywords: Suprarenal glands ; Imaging ; Anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé A partir de coordonnées relevées sur trois séries de coupes anatomiques, les auteurs ont imaginé une incidence d'exploration tomographique, utilisable en IRM et en échographie, qui restitue l'image idéale de la glande surrénale dans son quadrilatère décrit par Testut. Cette incidence “anatomique” est verticale et oblique à 45°, intermédiaire entre les incidences sagittale et frontale auxquelles elle se substitue avantageusement. Un aspect nouveau du tomogramme surrénalien, rappelant l'image d'un triskèle, est décrit à propos de cette incidence.
    Notes: Summary Based on coordinates derived from three series of anatomic sections, the authors propose a view for tomographic investigation, applicable in MRI and ultrasound, which reconstructs the ideal image of the suprarenal gland in its quadrilateral as described by Testut. This “anatomic” view is 45° vertical and oblique, intermediate between the sagittal and frontal views, which it can advantageously replace. A new aspect of suprarenal tomography, recalling the image of a triskele, is described in the context of this view.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Algebra universalis 16 (1983), S. 163-166 
    ISSN: 1420-8911
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The containmentS n⫅L n is proper. (Here n≥2 is a positive integer,S n is the “small” variety of lattice-ordered groups of Scrimger andL n is the variety of lattice-ordered groups defined by the law anbn=bnan.) Jo E. Smith proved this result for n a composite integer. In this note we proveS n≠L n when n is prime.
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  • 19
    ISSN: 1573-904X
    Keywords: Fourier transform-Raman ; polymorphism ; chlorpropamide ; factor analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We analyzed binary mixtures of polymorphs A and B of chlorpropamide ((l-[4-chlorobenzenesulphonyl]-3-propyl urea)) by near-infrared Fourier transform Raman spectroscopy (FTRS). The individual polymorphs were prepared and characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) microscopy, and physical appearance. The FTR spectra of the two polymorphs showed distinct differences which result from "crystal splitting” effects. A series of 13 different mixtures of polymorph A and B was prepared by geometric mixing and their FTR spectra statistically analysed by factor analysis programming. Predictions of the A/B polymorphic composition of mixtures were made and compared with the theoretical values. The results demonstrate that FTRS combined with factor analysis programming may be successfully applied to the in situ monitoring of the A/B polymorphic nature of a chlorpropamide sample.
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  • 20
    ISSN: 1573-904X
    Keywords: Fourier transform (FT)-Raman spectroscopy ; Eudragit RS ; sulfasalazine ; microspheres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract FT-Raman spectroscopy (FTRS) has been used to characterize microspheres produced from the pharmaceutical polymer Eudragit RS containing a range of concentrations of the drug sulfasalazine. While pure sulfasalazine produced an intense and complex Raman spectrum, the spectrum of drug-free Eudragit RS microspheres was considerably weaker in intensity and contained only a few prominent Raman scattering peaks. In spectra of the drug–polymer micro-spheres, peaks arising from the individual components could be identified. This enabled a quantitative analysis to be undertaken by calculating the ratio between the area of a sulfasalazine peak and the area of a Eudragit RS peak for each microsphere spectrum. A correlation was shown between the peak area ratio and the microsphere sulfasalazine content. FTRS was then applied to a series of microsphere samples which had been dissoluted into pH 7 buffer for 1, 3, 6, 9, 12, or 24 hr. For each spectrum, the drug-polymer peak area ratio was determined and this in turn enabled calculation of the residual drug content of the microsphere sample. FTRS-calculated data showed good agreement with microsphere drug content values determined spectrophotometrically.
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