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  • 1
    ISSN: 1432-0533
    Keywords: Brain Capillaries ; Brain Cortex ; Cat Brain ; Hypovolemia ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Histotopochemical and morphometric investigations were used to determine the following average values of capillary parameters in the cat's brain cortex: diameter $$\bar D_i$$ , percentage of the projected area $${{\bar A^0 } \mathord{\left/ {\vphantom {{\bar A^0 } {_{0^{Ai} } }}} \right. \kern-\nulldelimiterspace} {_{0^{Ai} } }}$$ , surface-to-volume ratio $${{\bar S_i } \mathord{\left/ {\vphantom {{\bar S_i } {\bar V_i }}} \right. \kern-\nulldelimiterspace} {\bar V_i }}$$ , free distances between capillary surfaces $$\bar \lambda$$ and length per unit brain volume $$\bar L_{Vi}$$ . These overall average values per stereotaxically defined brain region of 6 control and 6 hypovolemic animals were calculated by a computer. The hypovolemic condition was achieved by reducing the systemic arterial blood pressure to 50 mm Hg. The resulting hypovolemia caused a significantly diminished diameter $$\bar \bar D_i$$ , a highly increased length per unit brain volume $$\bar \bar L_{Vi}$$ and an improved surface-to-volume ratio $${{\bar \bar S_i } \mathord{\left/ {\vphantom {{\bar \bar S_i } {\bar \bar V_i }}} \right. \kern-\nulldelimiterspace} {\bar \bar V_i }}$$ of cortical capillaries. The behaviour of these 5 morphometric parameters during hypovolemic oligemia in the cat's brain cortex leads to the conclusion, that an adapted state of the capillary network may be a response to a reduced blood volume and blood pressure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European archives of psychiatry and clinical neuroscience 237 (1988), S. 91-100 
    ISSN: 1433-8491
    Keywords: Basilar artery stenosis ; Basilar artery occlusion ; Continuous-wave Doppler sonography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the past 5 years we have investigated 29 patients with symptomatic basilar artery stenoses (14 cases) and occlusions (14) and a patent primitive trigeminal artery with thin-calibered basilar and vertebral arteries (1) using directional continuous-wave Doppler sonography of the vertebral arteries. A total of 19 patients survived, and 17 of them were clinically and sonographically reexamined after 40.4 ± 15.8 months (mean ± SD). Among the 8 patients with basilar stenoses, 6 — with no further transient ischemic attacks (TIAs) in the interval — exhibited an increase in the summed modified Pourcelot indices (relative end-diastolic flow velocities) of the vertebrals by 0.18 ± 0.16; the other 2 showed a decrease by 0.26 each, in 1 case temporally related to a TIA, in the 2nd case without further clinical deterioration. In the 8 survivors with basilar occlusions, 5 remained — by sonographic criteria — unchanged with summed modified Pourcelot indices of the vertebrals of 0.00, while 3 patients exhibited a slight increase in the summed modified Pourcelot indices of 0.13 ± 0.03. While the difference between the outcome of subsets of patients treated with regimens of 30,000–40,000 units heparin/day or phenprocoumon and less radical drugs were statistically not significant, the former regimen appeared clinically more efficacious in preventing further deterioration in approximately two-thirds of the patients affected. Due to the potential recurrence of neurological symptoms, a treatment period with phenprocoumon of 6 months after discharge from hospital appears justified. Due to these therapeutic efforts, approximately half of the patients initially affected survived with no or only a mild neurological deficit. Directional continuous-wave Doppler sonography is, in our opinion, a reliable technique for examining the short- and long-term changes in peripheral vascular resistance.
    Type of Medium: Electronic Resource
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  • 3
    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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