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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Multilayer reflectors and position sensitive detectors have been developed in constructing imaging optical systems in the 45–300 A(ring) region. Molybdenum-silicon (2d=140 A(ring), N=20) and nickel–carbon (2d=100 A(ring), N=20) multilayers were deposited on a spherical mirror (25 cm in diameter) for the normal incidence and on a segment of paraboloidal mirror (20 cm×10 cm) for 30° grazing incidence. Their optical characteristics were evaluated by using characteristic x rays and monochromatized synchrotron radiation in the 45–300 A(ring) region. A position sensitive detector is made of a tandem microchannel plate (MCP) with a CsI photocathode and resistive plate, which is placed at the focal plane of each mirror. The detection efficiency and position resolution were measured by using characteristic x rays of CKα and monochromatized synchrotron radiation in the 45–200 A(ring) region.
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  • 2
    ISSN: 0942-0940
    Keywords: Brain death ; hypothalamic hormone ; pituitary hormone ; cerebral blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to find out the function of the hypothalamo-pituitary axis in brain dead patients, pituitary and hypothalamic hormone concentrations were measured and several anterior pituitary releasing tests were carried out in 39 brain dead patients. In addition, cerebral blood flow measurements were simultaneously performed. In almost all cases, the blood concentration of pituitary and hypothalamic hormones were above the sensitivity of the assay. Anterior pituitary releasing tests indicated that efficient functions of the hypothalamus were severely suppressed, while the normal secretory mechanism of the anterior pituitary was partially preserved in brain dead patients. Histological changes of hypothalamic neurons varied from barely detectable ghost cells to nearly normal cells even in the same case. Although, the remaining circulation seemed not to be sufficient enough to maintain integrated hypothalamo-pituitary function, as shown by the examinations of cerebral blood flow, the presence of hypothalamic hormones in the systemic circulation suggests that these hormones were released and carried from the hypothalamus by minimal flow which is preserved even after the diagnosis of brain death.
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  • 3
    ISSN: 0942-0940
    Keywords: Cerebral hyperaemia ; transcranial Doppler ; severe head injury ; cerebral oedema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Acute cerebrovascular congestion after a closed head injury is significantly related to intracranial hypertension. As an indirect method of cerebral blood flow measurement, transcranial doppler sonography (TCD) provides a rapid and noninvasive assessment of cerebral haemodynamics, including hyperaemic conditions. TCD examinations was serially performed in 35 patients with severe head injury with intact cerebral circulation; i.e. the mean flow velocity (MFV) patterns of the middle cerebral artery (MCA) did not show signs of cerebral circulatory arrest such as systolic spike, to and fro, or no flow. The results showed that the MFV of the MCAs and ipsilateral extracranial internal carotid arteries (ICAs) in 9 of these patients increased sharply and pulsatility index (PI) decreased during 48–96 hours after the injury. This was soon followed by patterns of high intracranial resistance, consistent with elevated intracranial pressure (ICP) in monitored patients and acute brain swelling on repeated computed tomographic (CT) scans. The correlation between increased MFVs, decreased PIs, and cerebral haemodynamic changes leading to acute brain swelling is discussed. The number of patients who ended with severe disability, vegetative state, or death was 66% in this group of 9 patients, compared to only 34% for the 35 patients overall with severe head injury. Though the morbidity and mortality rates largely depend on the primary injury, the presence of acute cerebral swelling aggravate the grave course in these patients. And the ability of TCD to monitor the hyperaemic state prior to oedema should lead us to adjust the therapy in order to minimize the secondary insult related to intracranial hypertension.
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  • 4
    ISSN: 1437-1596
    Keywords: Barbiturates ; Serum analysis ; GUMS (EI-SIM) ; Secobarbital therapy ; Barbiturate ; Serum-Analyse ; GC/MS (EI-SIM) ; Secobarbital-Therapie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Description / Table of Contents: Zusammenfassung Eine einfache und schnelle Methode zur Analyse von Barbituraten im Serum wurde entwickelt. Zur Probenaufarbeitung wurde eine Säulenextraktion mit Hilfe von Extrelut und Florisil angesetzt. Das Eluat wurde direkt analysiert mit Hilfe der GC/MS (EI-SIM). Als Ionen wurden die „base peaks” von 10 verschiedenen Barbituraten ausgewählt. Als interner Standard wurde Allobarbital oder Secobarbital verwendet. Innerhalb eines Bereiches von 0,5–5 ng wies die Eichkurve einen linearen Verlauf auf. Bei der Extraktion von gespeikten Serumproben, welche 20 μ1,5 ml und 5 μ1,5 ml enthielten, konnte eine Wiederfindungsrate von 87,2–105,2% und 81,6–104,6% gefunden werden. Phenobarbital stellt mit einer Wiederfindungsrate von 151,9% bzw. 172,1% eine Ausnahme dar. Die Secobarbital-Gehalte von 13 Patienten-Seren nach intravenöser Gabe von Secobarbital wurden analysiert. In 3 von 10 Fällen konnten Secobarbital-Spiegel von mehr als 1 μg/ml bei mehr als 72 Stunden zurückliegender Secobarbital-Gabe nachgewiesen werden. Die Methode scheint eine Möglichkeit zur klinischen Barbiturat-Spiegel-Bestimmung zu bieten.
    Notes: Abstract A simple and rapid method for analysis of barbiturates in serum has been developed. In order to extract and clean barbiturates in serum, a separation column packed with Extrelut and Florisil was used, and the eluate was directly analyzed by means of electron impact selected ion monitoring (EI-SIM). Selected ions used were base peak ions of 10 barbituartes, and the internal standard used was allobarbital or secobarbital. The calibration curves were linear over the range 0.5–5 ng. Extraction of replicate serum samples containing 20 μg/1.5 ml and 5 μg/1.5 ml resulted in a recovery of 87.2–105.2% and 81.6–104.6%, respectively, with the exception of phenobarbital, which was 151.9% and 172.1%, respectively. Secobarbital was also analyzed in the serum of 13 patients who had been given secobarbital intravenously. In 3 out of 10 cases, Secobarbital levels greater than 1 μg/ml were detected more than 72 h after administration. This method seems to have possibilities for clinical use.
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Multilayers of Pt/C, W/Si, and W/B4C have been developed as a reflector and dispersive element to be applied to the beamline optical system of the synchrotron radiation (SR) in 1- to 20-A region. Pt/C(2d=105 A, N=10) overcoated with Pt(d=100 A) is useful in a glazing incidence optics, which makes it possible to extend the wavelength region to the shorter side at the fixed incidence angle. W/Si(2d=53 A, N=200) and W/B4C(2d=31 A, N=300) are utilized as a dispersive element of double-crystal monochromator (DXM). The second order of Bragg reflection of W/Si is matched to the first order of KAP(2d=26.6 A) crystal. The characterization of these multilayers was carried out by using characteristic x rays and monochromatized SR in 1.5–8 keV. DXM was made of a combination of W/Si and KAP and a pair of W/B4C. Multilayers are used as the first crystal to protect the damage of the crystal caused by the strong irradiation of SR. A pair of W/B4C is aimed at getting high throughput. The energy resolution of these combinations was evaluated with Na–K absorption edge of NaCl around 1.07 keV, which was a bit poor compared to a pair of beryl crystals.
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