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Biomedical subjects

G F Hamann

Publications and source records attributed to G F Hamann.

68 records · Page 4Linked to original sources
PubMed1996

Time course of the acetazolamide effect in patients with extracranial carotid artery disease.

The acetazolamide test of cerebrovascular reserve is performed as a two-point transcranial Doppler (TCD) measurement of the flow velocity in the middle cerebral artery (MCA) before and 15 to 20 minutes after injection of the carbonic anhydrase inhibitor. The time course was evaluated by bilateral TCD monitoring over 45 minutes in 51 patients with extracranial carotid artery disease. Twenty-nine patients in Group 1 showed a unilateral and 22 patients in Group 2, a bilateral stenosis of the internal carotid artery (ICA). Thirty-one normal hemispheres in 18 normal subjects provided baseline control values. The most useful parameter for the description of the time course was the integral of the mean flow velocity. In both groups integral of the mean flow velocity was significantly reduced compared to that in normal persons (Group 1: 587.2 +/- 538.3 cm, p < 0.01; Group 2: 728.9 +/- 397.1 cm, p < 0.01; normal persons: 967.8 +/- 350.0 cm). The maximal increase of mean flow velocity in a two-point measurement also was significantly lower in the patient groups, but did not reach the same level of significance in Group 2 (Group 1: 19.6 +/- 12.3 cm/sec, p < 0.01; Group 2: 24.2 +/- 10.4 cm/sec, p < 0.05). Thirty-four of 73 hemispheres had reduced integral of the mean flow velocity, but only 29 had a reduced maximal increase. These data indicate that continuous monitoring and evaluation of the time course of the acetazolamide effect provide additional information on cerebrovascular reserve and help to detect an increased number of patients with impaired cerebrovascular reserve.

Acetazolamide↗
PubMed1996

[Cerebral infarct in chronic acetylsalicylic acid poisoning].

Salicylates increase the risk of hemorrhage. An ischemic brain infarct has not previously been described following intoxication with salicylates. Case report. A 58-year-old comatose patient was admitted with symptoms of a basilar artery thrombosis. A diagnostic angiography was impossible because laboratory results showed a prothrombin time (Quick) of 9% and a toxic salicylate level of 528 mg/l. During the next few days CCT and MRI scans revealed ischemic infarctions within the brain stem. Discussion. Salicylates can induce hemorrhage both by inhibiting platelet aggregation and - especially in higher doses - by vitamin K antagonism, leading to severe coagulopathy. The occurrence of an ischemic infarction, as presented in this case report, can be explained by a reduction of the vitamin K-dependent protein C level.

Aspirin↗
PubMed1996

Integrin alphavbeta3 is expressed in selected microvessels after focal cerebral ischemia.

The endothelial and smooth muscle integrin alphaVbeta3, a receptor for vitronectin and fibrinogen, participates in angiogenesis associated with wound healing and tumorigenicity. The microvascular expression of alphavbeta3 and fibrin during experimental middle cerebral artery occlusion and reperfusion in a nonhuman primate model was examined by computer-assisted video imaging microscopy. No microvascular expression of alphavbeta3 was seen in the control subjects (n = 3) or the non-ischemic basal ganglia of subjects undergoing 2-hour MCA:O (middle cerebral artery occlusion) or 3-hour occlusion with 1-hour (n = 3), 4-hour (n = 3), and 24-hour (n = 3) reperfusion. In the ischemic territory, alphavbeta3 appeared initially at 2 hours of middle cerebral artery occlusion. Up-regulation of alphavbeta3 was confined to the media of 30.0- to 50.0-micron-diameter arterioles in the ischemic core and correlated significantly with fibrin deposition in those vessels (P < 0.0005). Integrin alphavbeta3 and its ligand fibrinogen appear in a subpopulation of microvessels after focal cerebral ischemia.

Animals↗
PubMed1996

["Thunder clap headache": an independent form of headache?].

Acute severe headache indicative of subarachnoid haemorrhage (SAH), but without the requisite proof, is defined as thunderclap. A special pathophysiological mechanism for the development of this headache is not known as yet. This retrospective study comprised 84 patients. All had the typical clinical signs of a SAH, but cranial computer tomography and lumbar puncture excluded this diagnosis. In 82% of these patients the headache was classified according to aetiologically defined symptomatic groups. One patient with headache of vascular aetiology had an angiographically proven, but not ruptured aneurysm. No definite cause for the headache was found in 18% of cases. None of the patients followed up over a period of between 12 months and 6 years developed SAH or any other severe neurological disorder. 9% reported repeat of the headache event. Thunderclap headache seems to be only a descriptive term for patients with symptoms typical of a SAH without signs of bleeding. Thunderclap headache has no diagnostic or prognostic specificity and therefore we recommend use of this term only as a description of the headache characteristic. Thunderclap headache is not a predictor of a future SAH. Cerebral angiography should be restricted to cases with neurological deficits.

Adolescent↗
PubMed1995

Pattern of elevation of urine catecholamines in intracerebral haemorrhage.

Autonomic nervous system dysfunction is a common complication of severe intracranial disease. The aim of this study was to reveal the autonomic changes in patients suffering from acute intracerebral haemorrhage (ICH). 25 patients with spontaneous ICH within 24 hours of onset of symptoms were included. All patients were treated with standardised medical management and the meta- and normetanephrines were detected by high performance liquid chromatography (HPLC) in 24-hour urine every day. The mean level of normetanephrine (709 +/- 579 micrograms/day) and metanephrine (244 +/- 161 mg/day) were significantly elevated in comparison with a control group, p < or = 0.01. The norepinephrine elevation was of greater diagnostic and prognostic importance. Maximum urinary catecholamine metabolite levels occurred between day 3 to 10 after the bleeding. Normetanephrines correlated with the prognosis and the complications of ICH: intraventricular involvement resulted in significantly elevated normetanephrine levels (896 +/- 520 micrograms/day versus 311 +/- 78 micrograms/day) p < or = 0.01. Patients with a great volume of haematoma developed severe autonomic dysregulation (normetanephrines 1114 +/- 493 micrograms/day), whereas patients with smaller haematoma did not (339 +/- 125 micrograms/day) p < or = 0.0001; patients with bad outcome (1014 +/- 620 mg/day) had higher levels of normetanephrines than those with a good prognosis (322 +/- 110 micrograms/day) p < or = 0.001. A close relationship to elevated intracranial pressure was established. This study demonstrated the feasibility of detecting autonomic nervous system dysfunction in neurological intensive care patients by means of examination of the metabolites of the catecholamines in the urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Microvascular basal lamina antigens disappear during cerebral ischemia and reperfusion.

BACKGROUND AND PURPOSE: Changes in vascular permeability are well-known and important consequences of cerebral ischemia. The development of edema and of petechial hemorrhage is connected to altered vascular integrity. A major part in microvascular integrity is played by the basal lamina. METHODS: The fates of the basal lamina components laminin, fibronectin, and type IV collagen during middle cerebral artery occlusion (2 hours, n = 3) and occlusion (3 hours) with reperfusion (1 hour, n = 3; 4 hours, n = 3; and 24 hours, n = 4) were evaluated in the nonhuman primate. Specific monoclonal antibodies against these components were used. The number and size distribution of the microvessels in each specimen were determined by video-imaging microscopy, and the relative fluorescence intensity of laminin was semiquantified by laser confocal microscopy. Basal lamina antigen presentations were compared by double-stain immunofluorescence histochemistry. RESULTS: The number of microvascular structures defined by the presence of each basal lamina antigen decreased significantly up to 24 hours of reperfusion (P < .0001). The ratio of laminin-containing vessels between the ischemic and nonischemic territories decreased significantly from control (0.98 +/- 0.04) to 2 hours of ischemia (0.83 +/- 0.09) and 1 hour (0.79 +/- 0.08), 4 hours (0.77 +/- 0.06), and 24 hours of reperfusion (0.55 +/- 0.07). The ratio of fibronectin (cellular) and of collagen (IV)-containing vessels decreased from 0.98 +/- 0.04 to 0.75 +/- 0.1 and from 1.02 +/- 0.03 to 0.57 +/- 0.1, respectively. Mean laminin fluorescence intensity decreased from 76.1 +/- 6.0 U (controls) to 52.0 +/- 14.6 U (24 hours of reperfusion; P < .001). CONCLUSIONS: The significant parallel losses of three basal lamina components, both in number and intensity, contribute to loss of microvascular integrity. These phenomena may be important for understanding cell extravasation and the hemorrhagic consequences of acute stroke.

Animals↗
PubMed1994

Big endothelin in spontaneous intracerebral hemorrhage.

Plasma big endothelin (BE) levels were studied in 17 patients during the first 2 weeks following spontaneous intracerebral hemorrhage (ICH). Three patients had experienced an infratentorial hemorrhage of the pons and cerebellum. The group of 14 patients with supratentorial hemorrhage presented with 8 hematomas of the putamen, 4 of the capsula interna and 2 in the thalamus. Significant elevations of BE during the first 2 weeks after the initial ICH, significant differences between the different localisations and between patients with different prognoses were not apparent (mean BE level: 2.95 +/- 1.39, control group: 2.68 +/- 1.29 fmol/ml). These results support the theory that endothelins do not play a significant pathophysiological role in acute severe ICH.

Adult↗
PubMedDate not supplied

Neurochemical differences in the CSF between Binswanger's and Alzheimer's disease.

In 21 patients suffering from Binswanger's disease (BD) and in 53 patients suffering from Alzheimer's disease, we measured cerebrospinal fluid (CSF) concentrations of somatostatin-like immunoreactivity (SLI), high molecular weight form somatostatin (HMV-SST), somatostatin-25/28 (SST-25/28), somatostatin-14 (SST-14), Des-ala-somatostatin (Des-ala-SST), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA). The patients were classified into three stages of intellectual deterioration according to the global deterioration scale (GDS). Levels of SLI were significantly decreased in BD in general and in SDAT patients with severe dementia (GDS 7), compared to a control group (BD overall 19.7 +/- 11.6 fmol/ml, SDAT 18.6 +/- 7.9 vs. 30.5 +/- 8.6 fmol/ml in controls, p < 0.01 for both). In SDAT patients, SLI levels correlated with dementia scores (r = -0.65, p < 0.05), but not in BD. HVA levels were decreased significantly in SDAT and BD patients with severe dementia (SDAT 273.5 +/- 138.7, BD 224.3 +/- 69.9 vs. 364.9 +/- 103.8 nmol/ml, p < 0.01 in controls, p < 0.05 for both). In BD patients with light dementia (GDS 2-4), HVA levels were significantly elevated (p < 0.05). In BD, HVA levels correlated with dementia (r = -0.59, p < 0.01). 5-HIAA was significantly elevated in BD patients with light dementia (p < 0.05). Qualitative and quantitative changes in the molecular forms of SLI are compatible with a dysregulated posttranslational processing SDAT and BD. We also observed significant correlations between SLI, 5-HIAA and HVA in BD indicating a neurochemical heterogeneous and generalized process affecting several transmitter systems and functions. In summary, our study shows that despite their quite different neuropathology, SDAT and BD do not differ fundamentally in their neurochemical profile.

Aged↗
PubMedDate not supplied

Outcome of acute vertebrobasilar occlusions treated with intra-arterial fibrinolysis in 180 patients.

BACKGROUND AND PURPOSE: To evaluate predictors of recanalization and a favorable neurologic outcome in patients with acute vertebrobasilar occlusion (VBO) treated with local intra-arterial fibrinolysis (LIF). METHODS: The multicentric data of 180 patients with acute VBO treated with LIF were retrospectively evaluated. The modified Rankin scale (mRS) was used to evaluate the neurologic status before LIF and at the time of discharge. Patient's sex, age, etiology of VBO, recanalization, symptom duration before LIF, and pretreatment mRS were correlated with posttreatment mRS. Multiple logistic regression analysis was used to identify independent variables for recanalization and neurologic outcome. RESULTS: The overall mortality was 43%. Complete recanalization was achieved in 99 (55%) patients and a partial recanalization in 35 (19%) patients, respectively. Recanalization was significantly associated with a favorable outcome (P < .001). The success of recanalization was negatively correlated with the volume of the thrombus (P < .001). No correlation was found between site and etiology of VBO and recanalization. Neurologic outcome correlated strongly with the pretreatment mRS (P < .001) and also with age (P < .02). Coma lasting less than 4.5 hours led to a positive trend toward a better outcome after univariate testing (P < .001). CONCLUSIONS: Success of recanalization and neurologic status before treatment predict neurologic outcome in patients with VBO. Thrombus volume has an adverse effect on the recanalization success.

Acute Disease↗