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  • 1
    ISSN: 0942-0940
    Keywords: Gliomas ; gray matter ; positron emission tomography (PET) ; radiochemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Haemocirculatory and metabolic changes in seemingly normal brain tissue following radiochemotherapy including nimustine hydrochloride (ACNU) and tegafur (FT) were analyzed using oxygen-15 and fluorine-18 positron emission tomography (PET) in seven patients with gliomas. At an early stage (within one month) after radiochemotherapy, marginal increases in regional cerebral blood flow (rCBF) and cerebral blood volume (rCBV) were found contralateral to the tumour in gray matter which was apparently normal brain structure, as seen on computerized tomography (CT). The oxygen extraction fraction (rOEF) decreased significantly (p 〈 0.05 by a paired-t test) from that of the pretreatment study, due to surgical decompression and radiochemotherapy. At the late stage (three to thirty-one months with a mean of thirteen months), rCBF decreased significantly from the early stage study (p〈0.05); oxygen consumption (rCMRO2) fell in all cases significantly from the pretreatment study (p〈0.01) and from the early stage study (p〈0.05); consequently, rOEF remained unchanged at a level similar to the early stage study. Glucose consumption (rCMRGl) increased slightly as compared with the early stage study but failed to be restored to the level of the pretreatment study. Noteworthy was a coupling reduction of rCBF and rCMRO2—presumably, a late delayed effect of radiochemotherapy. These preliminary results indicate that with PET studies it may be possible to predict damage to normal brain tissue after radiochemotherapy.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0942-0940
    Keywords: Subarachnoid haemorrhage ; cerebral blood flow ; oxygen metabolism ; positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Haemodynamic and metabolic sequences were investigated in nine patients having subarachnoid haemorrhage (SAH) up to 3 months following aneurysmal rupture, using positron emission tomography (PET). In the pre-spasm stage (2–4 days after SAH) cerebral blood flow (CBF, ml/100 ml/min) was 45±11, the cerebral metabolic rate of oxygen (CMRO2, ml/100 ml/min) was 2.68±0.50, and cerebral blood volume (CBV, ml/100 ml) was 5.5±1.2. CBF within the normal range and a relatively low CMRO2, indicated relative hyperaemia. This was possibly due to the direct toxic effect of SAH on the brain metabolism. CBV was considerably elevated. The spasm stage (6–15 days after SAH) showed CBF values of 39±7, CMRO2 values of 2.42±0.50, and CBV values of 5.4±1.7. CBF decreased significantly (p〈0.05 vs pre-spasm stage), and CMRO2 also tended to decrease, while they were coupling. It is likely that this may have been induced by vasospasm. Thereafter, the PET parameters normalized gradually. During all the stages studied, significant laterality of the PET parameters was not observed. This may be because SAH and vasospasm provide diffuse pathophysiological conditions for the entire brain and cerebral arteries.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0942-0940
    Keywords: Keywords: Down regulation; nitric oxide; protein kinase C; subarachnoid haemorrhage; vasospasm.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  We previously showed that a canine basilar artery manifested tonic and potent, protein kinase C (PKC)-dependent contractions when nitric oxide (NO) was inhibited. We also reported a linear correlation between chronological changes in the angiographic severity of vasospasm, enhanced PKC, and attenuated guanosine, 13′,15′-cyclic monophosphate (cGMP) activity in a canine subarachnoid haemorrhage model. The activity of cGMP is an indicator of NO-function. Based on this evidence, we have hypothesized that PKC and NO regulate cerebral vascular tone. We particularly focused on the role of NO in a negative feedback mechanism on PKC activity in the maintenance of vascular tone. To further confirm our hypothesis, we investigated the effect of PKC down-regulation on the tonic vascular contraction induced by NO-inhibition.  Canine basilar artery was used in the experiment. Significant down-regulation of PKC activity in vascular smooth muscle cells was obtained by incubation with 10−5 mole/L of phorbol 12-myristate 13-acetate (PMA) for 24 hours. The tonic and potent contraction induced by NO-inhibition was completely suppressed in the PKC down-regulated artery, even though the artery manifested a significant contraction in high-K+ solutions. These results indicate an obligatory role of PKC activity in tonic contraction when NO is inhibited, and support our previous data. Nitric oxide induces vascular relaxation by inhibiting PKC activity. Subarachnoid haemorrhage impairs this inhibition, resulting in PKC-dependent vascular contraction, such as vasospasm.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0942-0940
    Keywords: Keywords: Parkinson's disease; subthalamic nucleus; stereotactic surgery.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  The neural activity pattern of the subthalmic nucleus (STN) was investigated in five patients with Parkinson's disease who were scheduled for electrode implantation for chronic stimulation of the STN.  The initial target was placed 8 mm or 10 mm lateral to the midline, 3 mm to 4 mm posterior to the midcommissural point, and 5 mm to 6 mm below the intercommissural (AC-PC) line. The STN was identified by semi-microelectrode recordings with a trajectory moving laterally in 2-mm steps. The amplitudes of multi-unit activities were relatively low at depths from 8 mm to 5 mm above and from 1 mm to 4 mm below the target, while those 4 mm to 0 mm above the target were significantly higher than at the other sites (ANOVA, Fisher's test, p〈0.05), with the highest amplitude at 2 mm above the target (91.0±23.3μv, n=15). In the mediolateral direction, amplitudes were relatively higher in the lateral portion, and amplitudes at 14 mm lateral to the midline were significantly higher than at the other sites (ANOVA, Fisher's test, p〈0.05). The target for chronic electrical stimulation was determined to be at the midpoint of the hyperactive STN, i.e., 12 mm lateral to the midline in three patients and 13 mm lateral in two patients. Movement-related neural activity was observed at 5 sites, i.e., 3 sites responded to passive movement of the contralateral wrist and 2 sites to passive knee and/or ankle movement.  In conclusion, our data show that the lateral part of the STN is hyperactive in PD, and recordings of neural activities contributed greatly to identifying the STN and determining the target for chronic stimulation within it.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 71 (1984), S. 69-90 
    ISSN: 0942-0940
    Keywords: Head injury ; cerebral contusion ; delayed traumatic intracerebral haematoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 25 cases of traumatic intracerebral haematomas of delayed onset were found among 775 cases of acute head injuries. All these 25 cases were analysed both clinically and with computed-tomographical studies. Their clinical features were different from those of classical “traumatische Spät-Apoplexie” originally described by Bollinger in 1891, in the following aspects; (A) absence of the symptom-free interval and (B) absence of apoplectic onset of symptoms after a relatively long lucid interval. These traumatic intracerebral haematomas of delayed onset were, on the other hand, characterized by the following; (1) the patient was injured when the head was in motion, (2) the injury was not necessarily severe, (3) the onset of signs and symptoms were gradual and insidious, (4) all 25 cases but 4, had cranial vault fractures and/or basal skull fractures, (5) precipitating factors could not be identified, though hypotensive episodes were present in 60% of cases, (6) intracerebral haematomas appeared within 72 hours following the head injury in most of cases, though more than 4 days later in a small number of cases, (7) the appearance of such intracerebral haematomas suggested an unfavourable outcome, (8) cerebral contusion might be a major contributory factor.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 126 (1994), S. 135-139 
    ISSN: 0942-0940
    Keywords: Cerebral blood flow ; oxygen metabolism ; bypass surgery ; focal cerebral ischaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to study the haemodynamic and metabolic changes following bypass surgery, the regional cerebral blood flow (rCBF), the oxygen extraction fraction (rOEF), the cerebral metabolic rate of oxygen (rCMRO2), and the cerebral blood volume (rCBV) were measured using a positron emission tomograph (PET) on 13 patients who had unilateral internal carotid artery and/or middle cerebral artery occlusion. The patients were divided into two subgroups according to pre-operative rOEF values from the arterial occlusion side: the misery perfusion group, which had high rOEF values (≧0.56), and the coupling perfusion group, which had normal rOEF values (0.38–0.48). A post-operative PET study was performed 1–2 months and/or 1–5 years following the surgery. Six of the misery perfusion cases showed a post-operative CBF increase, where an accompanying OEF decreased to its normal level, indicating an attenuated misery perfusion state. The CMRO2 values, however, remained low. The other 7 coupling perfusion cases had an ipsilateral CBF increase in the earlier PET study. We conclude that misery perfusion is attenuated following bypass surgery, although the procedure does not consistently improve oxygen metabolism.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 194 (1993), S. 266-273 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 169 (1990), S. 673-679 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Neurolinguistics 6 (1991), S. 243-251 
    ISSN: 0911-6044
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Linguistics and Literary Studies , Biology , Medicine
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0008-6215
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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