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Biomedical subjects

C Baumgartner

Publications and source records attributed to C Baumgartner.

At least 127 records · Page 7Linked to original sources
PubMed1989

Laminar cortical interactions during epileptic spikes studied with principal component analysis and physiological modeling.

The direct cortical responses (DCR) to electrical stimulation and electrically evoked interictal penicillin spikes (EIIS) were studied in the same rats using current source-density (CSD) analysis to directly compare regions of neuronal depolarization and hyperpolarization in neocortex. Principal component analysis (PCA) was further used to evaluate patterns of covariance in the CSD that were characteristic of interactions between pyramidal cell populations with spatially and temporally distinct transmembrane currents. A physical model was applied to the physiological interpretation of PCA results and the optimal model parameters used to estimate neuronal generators of recorded laminar field potentials. The data suggested that the DCR and EIIS were produced by the same neuronal circuit which could be represented by two anatomically distinct populations of pyramidal cells. The first of these populations was situated in the upper and middle layers (supragranular pyramidal neurons) and formed a dipolar CSD pattern that reversed polarity in layers II and III. The second deeper population (infragranular pyramidal neurons) extended throughout most of the cortical thickness and formed a dipolar CSD pattern that reversed polarity in layer V. We propose that excitatory intracortical connections of supragranular pyramidal cells may pathologically synchronize depolarization within the epileptic focus. In this way, supragranular pyramidal cells may provide a trigger mechanism for interictal spikes in neocortex.

Animals↗
PubMed1989

[Prognostic factors for long-term mortality and risk of stroke in patients with transient ischemic attacks].

The aim of the present study was to evaluate the natural course of patients with transient ischaemic attacks and to determine prognostic factors concerning long-term mortality and the incidence of stroke. 159 patients, who were hospitalized after transient ischaemic attacks at the Neurological University Department Vienna during the years 1976 to 1985, were asked about the further course of their illness using questionnaires. 22 patients had moved to unknown addresses and the return rate of the remaining questionnaires was 73.0%. Thus, the results of 100 patients were included in the present study. The follow-up period was 71 +/- 32 months (x +/- s; range: 19-135 months). During the follow-up period, 11 patients had died and 25 had eventually incurred full-blown cerebral infarction. The following variables were analyzed for their prognostic relevance with respect to long-term mortality and stroke occurrence: sex, age, vessel territority involved clinically, number of vessel territories involved clinically, number of strokes, and severity of clinical symptoms. The clinical symptoms (motor deficits, sensory deficits, speech disorders, visual field defects and organic mental syndrome) were graded semiquantitatively and added up to a "total score". Age had a significant influence on survival, but not on stroke occurrence. All other variables had no significant impact on long-term mortality and stroke occurrence. It is concluded that transient ischaemic attacks are warning symptoms of an impending stroke. However, prognostic assumptions cannot be made of the basis of clinical features in this subacute stage. Thus, all patients suffering from transient ischaemic attacks should have a comprehensive and thorough vascular investigation as soon as possible.

Adolescent↗
PubMed1989

Neuromagnetic field modeling of multiple brain regions producing interictal spikes in human epilepsy.

A method of spatiotemporal analysis, using multiple current dipoles to represent activity in multiple brain regions, was applied to the interpretation of extracranial neuromagnetic fields generated by epileptic spikes in patients with focal seizure disorders. This method permitted the identification and approximate localization of cellular currents within single and multiple brain regions engaged over the entire duration of the human epileptic spike complex. These results suggest that spatially and temporally overlapping electrical currents in human epileptic cortex may be investigated non-invasively in the magnetoencephalogram if appropriate physical models are applied.

Brain↗
PubMed1989

Investigation of multiple simultaneously active brain sources in the electroencephalogram.

We present a method of investigating multiple simultaneously active brain sources that overlap both in space and time in the scalp electroencephalogram (EEG). In order to identify the contributions of the individual brain sources to measured potentials, we applied principal component analysis and various methods of rotating the principal components including a newly developed rotation procedure using frequency criteria. We related the results of these multivariate statistical techniques to a new physical model using multiple current dipoles with fixed anatomical locations and time-varying activities. We thus are able to study 3-dimensional location, time activity and interaction of multiple simultaneously active brain sources in the scalp EEG.

Brain↗
PubMed1989

Longterm prognosis of analgesic withdrawal in patients with drug-induced headaches.

We studied long-term prognosis and prognostic variables for therapeutic outcome of analgesic withdrawal in 54 patients with drug-induced headaches. The duration of headache history was 21.9 +/- 12.8 years. Each patient took an average of 38.8 +/- 22.8 tablets or suppositories a week and an average of 2.5 distinct drugs. Most patients used drugs containing several components. Caffeine was contained in at least one drug in all cases, ergotamine in 80.0% and pyrazolone in 77.1%. All patients were admitted to the hospital for two weeks. The analgesics were discontinued abruptly and the withdrawal symptoms were alleviated by neuroleptics and neurotropics. During the second week of hospital stay we started a basic therapy with calcium antagonists or beta blockers in patients suffering from migraine initially and with tricyclic antidepressants, physical therapy or biofeedback in patients suffering from tension type headaches initially. At the end of the study (mean follow-up period = 16.8 +/- 13.6 months) 38 patients (70.1%) were evaluated. 76.3% of these patients had significantly reduced their analgesic intake, 60.5% had experienced a significant relief of headache both in intensity and frequency, and 23.7% were therapeutic failures. Analysis of the time course of relapse revealed the first six months after hospital discharge as the critical period determining long-term success. The variables tested for prognostic relevance (age, sex, duration of headache history, number of tablets or suppositories taken a week, organic mental syndrome, and type of initial headaches) were not statistically significant.

Adult↗
PubMed1989

Stabilizing and destabilizing effects of vision and foot position on body sway of healthy young subjects: a posturographic study.

A total of 800 posturographic measurements--each characterized by four values (sway path, sway area, anteroposterior sway and lateral sway)--was carried out for this study. Eight different conditions (interfoot distances of 0, 4, 10 and 20 cm, each with eyes open and eyes closed) were compared by statistical means. All sway values were diminished by vision in small interfoot distances. At large interfoot distances, however, the presence of visual control resulted in an increase of lateral sway. Comparing the different foot positions, an increase of anteroposterior sway and a decrease of all other components were found at large interfoot distances no matter whether the eyes were open or closed.

Adult↗
PubMed1989

Quantification of regional cerebral blood flow with IMP-SPECT. Reproducibility and clinical relevance of flow values.

Single-photon emission computed tomography with N-isopropyl[123I]-p-iodoamphetamine (IMP-SPECT) was performed in 14 normal volunteers (seven men and seven women aged 25.1 +/- 5.3 years) and 29 patients with cerebrovascular disease (18 men and 11 women aged 54.1 +/- 13.7 years). The fluid microsphere model was used to estimate cerebral blood flow (CBF). Normal subjects were scanned twice, 1 week apart, to determine the reproducibility of the CBF estimates. Hemispheric blood flow (hCBF) was calculated as the mean of regional cerebral blood flow (rCBF) values in 16 gray matter regions per hemisphere. In normal subjects mean hCBF was 68 ml/100 g/min. The highest rCBF was found in the occipital cortex, followed by the frontal, temporal, and parietal cortexes. CBF values were reproducible (p less than 0.001 except the right thalamic region, where p less than 0.01). Intraindividual variation ranged between 0.3% and 15%. Women exhibited significantly higher (16%, p less than 0.02) CBF than men. Patients were subdivided into groups with reversible (n = 19) and persistent (n = 10) symptoms. Significant hCBF differences between the affected and the contralateral hemispheres were recorded only in the group with reversible symptoms (p less than 0.005), whereas the group with persistent symptoms showed a significant bilateral decrease of hCBF compared with normal subjects and patients with reversible symptoms. Focal CBF was significantly lower in patients with completed stroke than in patients with transient symptoms (p less than 0.001). Our results indicate that IMP-SPECT can be used for the routine estimation of CBF in normal and pathologic states.

Aged↗
PubMed1989

[Serum immunoglobulin concentrations in patients following bone marrow transplantation and preventive administration of high-dose nonspecific or normal-dose CMV-specific immunoglobulin].

Ten consecutive bone marrow transplant recipients were assigned alternatively to receive either a high dose polyspecific intravenous immunglobulin (HDIVIG) 0.5 g/kg weekly X 14, or a conventional dose of a CMV specific intravenous immunglobulin (CMVIG) 0.1 g/kg every three weeks. Before and after each application we determined the levels of total IgG, IgG subclasses, IgG 1, IgG 2, IgG 3, IgG 4, total IgA and IgM and of specific IgG and IgM antibody concentrations against endotoxin, lipid A, streptococcus A, hemophilus, EBV and CMV. In the HDIVIG, total IgG rose from 11 (median, range 2-11) g/l to 25 (22-32) g/l by day 89, in the CMVIG group, IgG dropped from 11 (10-15) g/l to 9 (6-12) g/l. In the same period the mean levels of IgG subclasses expressed as % of normal plasma pool increased in the HDIVIG group in all subclasses, not in the CMVIG group. The differences were significant, however, only for IgG 1 and IgG 2. IgG-antibodies against CMV, EBV, endotoxin, streptococcus and hemophilus did increase significantly in the HDIVIG group, but not in the CMVIG group. No increase was seen in both groups in lipid A antibodies and in specific IgM antibodies. Each application of CMVIG induced a transient increase of anti-CMV antibodies. We conclude that HDIVIG induces reproducibly an increase of specific and non-specific IgG antibodies. No attempt was made to assess clinical outcome. However, these results provide a rational basis for further therapeutic studies.

Adult↗
PubMed1989

[Evoked potentials in the follow-up and prognosis of patients with craniocerebral trauma].

The aims of this study were to find a reliable way of establishing the prognosis for the final outcome in the first week after head injury, to show the correlation between abnormalities in evoked potentials (EP) and clinical coma score, and finally, to document EP results in patients with the clinical diagnosis of brain death. We examined 46 patients, 23 in different states of coma and 23 with bulbar syndrome (complete absence of cortical and brain stem function). In the group of comatose patients brain stem auditory EP (BAEP) and somatosensory EP (SEP) were recorded in the first 48 h, 3-5 days, 1 week and 4 weeks after the head injury. The depth of coma was scaled with a scoring system devised by the authors and with the Innsbruck coma scale. Outcome was evaluated with the Glasgow outcome scale after 3, 6, and 9 months. BAEP were recorded bilaterally after stimulation with clicks; SEP were recorded from the neck (C2) and the contralateral cortex (C3', C4') after electrical stimulation of the median nerve. Evoked potentials were scored according to a four-point scale from grade 1 (normal) to grade 4 (only component I present in BAEP or absence of cortical responses on both sides in SEP). We found a significant correlation between the mean SEP score of the first week and the Glasgow outcome of the 3rd month, but no significant correlation between the BAEP score of the first week and the Glasgow outcome. There was a significant correlation between SEP (BAEP) scores and the corresponding clinical score.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

[Persistent changes in tissue-type plasminogen activator and plasminogen activator inhibitor fibrinolytic parameters in patients following juvenile ischemic cerebral infarct].

In diseases associated with thrombotic or thromboembolic complications, a reduction in the fibrinolytic potential may contribute to the risk to develop thrombosis. To investigate whether juvenile cerebral infarction is associated with a permanent defect of the fibrinolytic system we measured the main components of the fibrinolytic system, tissue plasminogen activator (t-PA) and its fast acting inhibitor (PAI) in plasma samples of 21 patients (aged 21-44 years) 3-24 months after the acute event. The data obtained were compared to those from thirteen healthy young volunteers (22-46 years). A direct effect of known risk factors on the fibrinolytic system could be excluded because patients avoided their risk factors immediately after the ischemic cerebral attack. Hypertension and the combination of oral contraceptives and smoking had been the most striking original risk factors. Levels of t-PA antigen and t-PA activity before and after venous occlusion, or PAI activity were not different between patients and controls suggesting that at least a permanent decrease in the activity of the fibrinolytic system does not exist in these patients. However, our findings do not exclude that a temporary defect in fibrinolysis might have contributed to the acute onset of the thrombotic cerebral event possibly induced by the risk factors originally present.

Adult↗
PubMed1988

[2-year anti-HIV donor screening in the Central Laboratory of the Swiss Red Cross Blood Transfusion Service].

612526 blood donations collected by the Central Laboratory of the Swiss Red Cross Blood Transfusion Service between July 1985 and June 1987 were routinely tested for antibodies to HIV.96 donations (82 men, 14 women were anti-HIV positive (0.157%, 1 of 6369 donations). The prevalence of anti-HIV positive donations was higher in men (0.172%, 1/5814) than in women (0.104%, 1/9615). Donations collected in military units were markedly more frequently seropositive (0.570%, 1/1754 in refresher courses, 0.261%, 1/3831 in recruit training). Excluding military donations, donations from men (0.077%) were less frequently HIV-seropositive than donations from women (0.104%). The prevalence of seropositive donations was 4.4 times higher in new donors than in repeat donors. Regarding age distribution, the peak of seropositive donations was observed, as expected, in the third decade. Donations from French speaking Swiss had a clearly higher HIV prevalence than those of German speaking Swiss. As a result of continuous donor information and selection, the number of anti-HIV positive results decreased during the 4 half years covered by our study. It was lowest at the end of the observation period (0.098% or 1/10200 between January and June 1987). Doubtful positive results were recorded chiefly among women, at a rate increasing with age. The majority of such results are presumably due to antibodies with other specificities and must therefore be considered false positive.

Blood Donors↗
PubMed1988

[Does alcohol consumption promote the manifestation of strokes? Considerations on pathophysiology].

Arterial hypertension is the most important risk factor in all types of stroke. The significance of alcohol in the pathogenesis of stroke is less well defined. Chronic alcoholism leads to an elevation of blood pressure. Thus, the association between alcohol and stroke might be the blood pressure effect of alcohol. However, some studies have shown a significant influence of alcohol on the incidence of stroke--especially of intracerebral haemorrhage and subarachnoid haemorrhage--even after adjustment for blood pressure. Many possible pathomechanisms are discussed. Alcohol inhibits aggregation of thrombocytes, and chronic alcohol abuse may induce thrombocytopenia, which could lead to a haemorrhagic stroke. Alcohol withdrawal leads to rebound thrombocytosis. Acute alcohol ingestion induces a decrease in fibrinolytic activity and an increase in factor VIII activity, which enhances the thrombotic potential. Additionally, alcohol increases plasma osmolarity, erythrocyte aggregability, haematocrit and blood viscosity, and decreases deformability of erythrocytes. The effects of alcohol on cerebral blood flow are still under debate; there is a deterioration in autoregulation of cerebral blood flow anyway. In animal studies alcohol induced dose-dependent vasospasm of the cerebral blood vessels, which could be a possible pathomechanism in ischaemic, as well as in haemorrhagic stroke. Chronic alcoholism is the most common cause of secondary non-ischaemic cardiomyopathy, which can lead to cerebral embolism via rhythm disorders or intracardiac thrombus formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1988

[Somatosensory evoked potentials following tibial nerve stimulation. Method and normal values in relation to physical variables].

Somatosensory evoked potentials were recorded in 40 healthy subjects (age: 22-63 years) with gluteal, lumbar, cervical and cortical surface electrodes after stimulation of the tibial nerve. Normal latency values were established in relationship to height and also for the amplitudes of the different components; the latencies of the cortical P40, N50 and P60 were significantly dependent on height, the latency of the cervical N33, the lumbar N22 and the gluteal Ng were dependent on the distance (stimulation--to recording point). The central conduction time showed no dependence on back length. Age dependence (in relation to normal height) was found only in the case of cortical P60.

Adult↗
PubMed1988

Intravenous immunoglobulin (i.v. IgG) for previously treated acute or for chronic idiopathic thrombocytopenic purpura (ITP) in childhood: a prospective multicenter study.

In a prospective multicenter study 42 thrombocytopenic (less than 30 X 10(9) platelets/l) children with chronic idiopathic thrombocytopenic purpura (ITP) or with acute ITP, dependent on or refractory to corticosteroids, were given 0.4 g i.v. IgG/kg body weight/day on 5 consecutive days and thereafter once a week if the platelet count fell to less than 20 X 10(9)/l or if the patient bled. After the initial 5 days of i.v. IgG the platelets rose within a mean of 7-8 days to greater than 30 X 10(9)/l in all and to greater than 150 X 10(9)/l in 33 of 42 patients (79%). After a mean observation time of 26.6 months 26 of 42 patients (62%) showed a satisfactory long-term effect, i.e. no need for treatment for at least 6 months without bleeding and with no platelet counts below 20 X 10(9)/l. No difference in response rate was found between children with chronic and those with previously treated acute ITP. These results indicate that i.v. IgG could be used to control emergency situations, e.g. to stop bleeding or to prepare a patient for surgery. I.v. IgG also represents a good alternative to treatment modalities, such as splenectomy and/or the administration of cytostatic immunosuppressants with potentially serious side effects. In addition to the expected transient rise in serum IgG levels, i.v. IgG induced a more prolonged elevation of serum IgM. Platelet associated IgG, elevated before therapy, was correlated with the clinical long-term outcome.

Acute Disease↗
PubMed1988

The inducibility of coronary artery spasm after successful PTCA.

An ergonovine test (0.2 mg ergonovine i.v.) was performed on 32 consecutive patients showing a good long-term result 3 to 6 months after successful PTCA. In seven patients (22%) a significant spasm could be induced. Six of the seven patients complained of atypical chest pain as compared to two of 25 patients with a negative test. This difference was statistically significant (P less than 0.01). These results implicate that a higher vasomotor tone at the site of previous stenosis is responsible for atypical chest pain in patients after successful PTCA and good angiographic long-term follow-up. The application of long-term nifedipine and nitroglycerin in this patient group seems to be indicated.

Adult↗
PubMed1988

Is aphasia an additional prognostic factor in ischemic stroke with regard to the severity of hemiparesis in the subacute stage?

The outcome of 122 patients with ischemic stroke in the left carotid territory (ascertained by CT) was investigated using mailed questionnaires after a mean follow-up time of 60.7 months (SD 20.5 months). Patients who had had cerebrovascular accidents others than TIA prior to the stroke were not included in the study. The relationship between the degree of aphasia in the postacute stage and the long-term outcome was evaluated with regard to the severity of motor deficits. With respect to survival, recurrent stroke, single activities of daily living such as dressing, personal hygiene, walking, feeding, bowel management and overall self-care status, the outcome of patients was not dependent on the severity of aphasia. Aphasia did also not serve as a prognostic factor in returning to work after left hemispheric cerebral infarction. Our results indicate that in presence of motor deficits the severity of aphasia in the subacute stage does not additionally influence the long-term outcome after left hemispheric cerebral infarction.

Activities of Daily Living↗