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  • 1
    ISSN: 1432-1440
    Keywords: Human corticotropin-releasing hormone ; Flush-blood flow-Doppler sonography ; Medial cerebral artery ; External carotid artery ; Extracerebral blood flow ; Intracerebral blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To study facial flush after systemic administration of human corticotropin-releasing hormone (hCRH) we injected 100 μg hCRH intravenously to ten healthy young men. The increase in facial temperature was measured by infrared camera. A significant increase in facial temperature of 1.39°C ± 0.3 was found within 7 min in all patients, which lasted up to 60 min, although facial flushing was visible in only 50% (5/10) of the probands. In a second experiment 100 μg hCRH was then administered to seven other healthy young men. Intra- and extracerebral blood flow velocity changes in the medial cerebral artery (MCA) and external carotid artery (ECA) were measured after hCRH administration by use of Doppler sonography. We found a decrease of intracerebral blood flow which was caused by hyperventilation and was reversible following 6% CO2 hyperventilation during a second injection of 100 μg hCRH. Blood flow velocity in the ECA increased by 111.5 ± 32.9% (compared to baseline level), lasted up to 60 min after hCRH injection, and was not reversible by 6% end-tidal CO2 ventilation. We thus demonstrated that the direct vasodilatory effect of hCRH involves the ECA-supplied vascular territory only. The intracerebral vasoconstrictory effect represents the result of hyperventilation following hCRH injection. The data thus clearly suggest an interaction of hCRH and the vascular endothelium of the ECA, causing a marked blood flow velocity increase and facial flushing.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Clinical rheumatology 12 (1993), S. 364-367 
    ISSN: 1434-9949
    Keywords: Ultrasound ; Cortical bone ; Mechanical Properties ; Architecture ; Modulus of Elasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The square of ultrasound transmission velocity in a material is correlated to the modulus of elasticity, which is an indicator of its mechanical properties. This might make the measurement of ultrasound transmission velocity useful in the noninvasive diagnosis of bone diseases. Bone, however, is not an isotropic material but is architecturally structured. The aim of our study was to investigate and especially to quantify the influence of architecture in cortical bone on ultrasound transmission velocity. Twenty-two rectangular, flat specimens of cortical bone were prepared from diaphysis of fresh pig radius. Ultrasound transmission velocity was measured parallel and perpendicular to direction of Haversian channels. It was found to be 3647 ± 41 m/s parallel to and 2821 ± 29 m/s perpendicular to Haversian channels respectively (p〈0.001). Our results clearly indicate that there is an important influence of architecture in cortical bone on ultrasound transmission velocity which has to be taken into account in its clinical use.
    Type of Medium: Electronic Resource
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