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D Lehmann

Publications and source records attributed to D Lehmann.

At least 19 recordsLinked to original sources
PubMed2001

Decreased functional connectivity of EEG theta-frequency activity in first-episode, neuroleptic-naïve patients with schizophrenia: preliminary results.

We explored and refined the hypothesis that during a first episode of acute schizophrenia a disorganization of brain functioning is present. A novel EEG measure was introduced, Global Field Synchronization (GFS), that estimates functional connectivity of brain processes in different EEG frequency bands. The measure was applied to EEG's from 11 never-treated, first-episode, young patients with an acute, positive, schizophrenic symptomatology and from 19 controls, residing in Bern, Switzerland. In comparison to age- and sex- matched controls, patients had significantly decreased GFS in the theta EEG frequency band, indicating a loosened functional connectivity of processes in this frequency. The result was confirmed in an independent, comparable patient group from Osaka, Japan (9 patients and 9 controls), thus making a total of 20 analyzed patients. Previous EEG research in healthy, awake subjects indicated a positive correlation of theta activity with memory functions. Thus, our result suggests a loss of mutual interdependence of memory functions in patients with acute schizophrenia, which agrees well with previous reports of working memory dysfunction in schizophrenia.

Acute Disease↗
PubMed2001

Source localization of EEG activity during hypnotically induced anxiety and relaxation.

The engagement of different brain regions which implement subjectively experienced emotional states in normals is not completely clarified. Emotional states can conveniently be induced by hypnosis-based suggestions. We studied brain electric activity during hypnotically induced anxiety and relaxation in 11 right-handed normals (5 males, 6 females, mean age 26.5+/-7.6 years). After induction of light hypnosis, anxiety and then relaxation was suggested using a standardized text (reverse sequence in half of the subjects). Nineteen-channel, eyes-closed EEG (20 artifact-free s/subject) was analyzed (source localization using FFT approximation and low resolution electromagnetic tomography, LORETA). Global tests revealed the strongest difference (P<0.005) between EEG source gravity center locations during the two emotional states in the excitatory beta-2 EEG frequency band (18.5-21 Hz). Post hoc tests showed that the sources were located more right during anxiety than during relaxation (P=0.01). LORETA specified that anxiety showed maximally stronger activity than relaxation in right Brodmann area 10, and relaxation showed maximally stronger activity than anxiety in left Brodmann area 22. Clearly, the two induced emotional states were associated with activity of different neural populations. Our results agree with reports on brain activity shifted to the right (especially fronto-temporal) during negative compared with positive emotions, and support the role of beta-2 EEG frequency in emotional states.

Adult↗
PubMed2000

Brain electric correlates of strong belief in paranormal phenomena: intracerebral EEG source and regional Omega complexity analyses.

The neurocognitive processes underlying the formation and maintenance of paranormal beliefs are important for understanding schizotypal ideation. Behavioral studies indicated that both schizotypal and paranormal ideation are based on an overreliance on the right hemisphere, whose coarse rather than focussed semantic processing may favor the emergence of 'loose' and 'uncommon' associations. To elucidate the electrophysiological basis of these behavioral observations, 35-channel resting EEG was recorded in pre-screened female strong believers and disbelievers during resting baseline. EEG data were subjected to FFT-Dipole-Approximation analysis, a reference-free frequency-domain dipole source modeling, and Regional (hemispheric) Omega Complexity analysis, a linear approach estimating the complexity of the trajectories of momentary EEG map series in state space. Compared to disbelievers, believers showed: more right-located sources of the beta2 band (18.5-21 Hz, excitatory activity); reduced interhemispheric differences in Omega complexity values; higher scores on the Magical Ideation scale; more general negative affect; and more hypnagogic-like reveries after a 4-min eyes-closed resting period. Thus, subjects differing in their declared paranormal belief displayed different active, cerebral neural populations during resting, task-free conditions. As hypothesized, believers showed relatively higher right hemispheric activation and reduced hemispheric asymmetry of functional complexity. These markers may constitute the neurophysiological basis for paranormal and schizotypal ideation.

Adult↗
PubMed2000

Efficacy and effectiveness of pneumococcal polysaccharide vaccines and their use in industrialised countries.

Use of pneumococcal polysaccharide vaccines remains controversial, even though clinical trials have shown their efficacy in preventing invasive disease caused by vaccine serotypes in immunocompetent adults. Retrospective studies indicate these vaccines have about 50%-80% effectiveness for preventing invasive disease caused by vaccine serotypes, although effectiveness wanes over time and with age. The elderly, people living in institutions and those with chronic cardiac or respiratory disease, alcoholism or diabetes mellitus who are in relatively good health would benefit from vaccination; a polysaccharide vaccine program in the elderly has been shown to be cost-effective. In young children, polysaccharide vaccine should be evaluated as a booster to conjugate pneumococcal vaccines, which are likely to be available soon in industrialised countries. In view of the high rates of hospitalisation and of antimicrobial resistance in pneumococci, every effort should be made to increase coverage by pneumococcal polysaccharide vaccine in Australia, according to guidelines of the National Health and Medical Research Council.

Adult↗
PubMed2000

Mood state and brain electric activity in ecstasy users.

Resting EEG during open and closed eyes and subsequent mood ratings were obtained from 15 Ecstasy users and 14 Ecstasy-naive controls. Absolute spectral power on the scalp, and the three-dimensional, intracerebral distribution of neuroelectric activity using low resolution brain electromagnetic tomography (LORETA) were computed. LORETA revealed global increases of theta, alpha 1 and beta 2/3 power during eyes open in Ecstasy users, and spectral analyses revealed a right-posterior increase of alpha 2 power (confirmed by LORETA) and increased beta band activity during open eyes. Ecstasy users had higher levels of state depressiveness, emotional excitability and a trend-level increase in state anxiety. The observed differences may be related to regular exposure to Ecstasy or other illicit drugs, or may be pre-existing.

Adult↗
PubMed2000

Face-elicited ERPs and affective attitude: brain electric microstate and tomography analyses.

OBJECTIVES: Although behavioral studies have demonstrated that normative affective traits modulate the processing of facial and emotionally charged stimuli, direct electrophysiological evidence for this modulation is still lacking. METHODS: Event-related potential (ERP) data associated with personal, traitlike approach- or withdrawal-related attitude (assessed post-recording and 14 months later) were investigated in 18 subjects during task-free (i.e. unrequested, spontaneous) emotional evaluation of faces. Temporal and spatial aspects of 27 channel ERP were analyzed with microstate analysis and low resolution electromagnetic tomography (LORETA), a new method to compute 3 dimensional cortical current density implemented in the Talairach brain atlas. RESULTS: Microstate analysis showed group differences 132-196 and 196-272 ms poststimulus, with right-shifted electric gravity centers for subjects with negative affective attitude. During these (over subjects reliably identifiable) personality-modulated, face-elicited microstates, LORETA revealed activation of bilateral occipito-temporal regions, reportedly associated with facial configuration extraction processes. Negative compared to positive affective attitude showed higher activity right temporal; positive compared to negative attitude showed higher activity left temporo-parieto-occipital. CONCLUSIONS: These temporal and spatial aspects suggest that the subject groups differed in brain activity at early, automatic, stimulus-related face processing steps when structural face encoding (configuration extraction) occurs. In sum, the brain functional microstates associated with affect-related personality features modulate brain mechanisms during face processing already at early information processing stages.

Adult↗
PubMed2000

[Sonographic representation of the normal and acute inflamed appendix--in patients wi right-sided abdominal pain].

The detectability, vascularization and size of the normal and inflamed appendix were investigated in the study. 148 patients under suspicion of appendicitis or with lower right abdominal pain were studied over a period of five months beginning in January 1998. An ultrasound-transducer was employed at a wave length of 3.5 MHz to 10 MHz. Vascularization was measured using 'Duplex' and 'Color Angio'. The results were compared with operative evidence, histology and patient history. The appendix was detected in about 30% of the cases (47/148). But of the presumably normal appendices only 12% (13/109) were detected. 27 appendices sonographically diagnosed as acutely inflamed were confirmed by operation and phlegmonic. The acute appendicitis was sonographically diagnosed with a sensitivity of 82% and a specificity of 95%. The diameter of the normal appendices was an average of 5.5 mm, that of the acute was 12.2 mm whereby 21 of 25 organs were at least 9 mm. The measurement of the organ size seems to be more helpful than the detection of vascularization. Both methods alone cannot detect the acute phlegmonic appendicitis. The normal appendix was less frequently detected than described in current literature. Patients with pain present difficulties in ultra-sound examination because both the cooperation and the time for the correct diagnosis are limited.

Abdominal Pain↗
PubMed2000

Self-adjusting continuous positive airway pressure therapy based on the measurement of impedance. A comparison of free pressure variation and individually fixed higher minimum pressure.

BACKGROUND: Measurement of impedance using forced oscillation technique is a sensitive means of detecting airway obstructions, including the obstructive sleep apnea syndrome (OSAS). OBJECTIVE: The present study was conducted to determine whether treatment with an automated impedance-controlled continuous positive airway pressure (CPAP) device (APAP(FOT)) is possible in patients with OSAS, and which is the best range of pressure variation in automatical CPAP treatment. We investigated two modes of APAP(FOT) with different pressure ranges: (1) the widest technically possible pressure range and (2) a range with individually defined minimum pressure. METHODS: Ten patients [9 men, age 56.6+/-10.5 years, BMI 32.0+/-4.5 kg/m(2), apnea/hypopnea index (AHI) 18.2+/-13.3 /h] had a diagnostic polysomnography (baseline). After manual titration of positive airway pressure they were submitted, in randomized order, to two modes of the APAP(FOT) device, namely pressure range of 4.0- 15.5 mbar (mode 1 free range) and an individually fixed higher minimum pressure with a maximum pressure of 15.5 mbar (mode 2). RESULTS: While the manually titrated pressure was 8.0+/-1.3 mbar, in mode 1 it was 5.6+/-2.1 mbar (p<0.01); in mode 2 7.3+/-1.6 mbar (p< 0.05). Both of these modes suppressed abnormal respiratory events (baseline AHI 18.2+/-13.3/h; mode 1: 2.5+/-1.9; mode 2: 1.8 +/-0.7, p<0.01 in each case), and increased slow wave sleep (baseline: 10.6+/-8.0%, mode 1: 20.2+/-10.4%, p<0.05; mode 2: 22.3+/-9.3%, p<0.01). In mode 1, the pressure was lower than that titrated manually in 73.2% of total sleep time, in mode 2 in 48.6%, while pressures higher than those derived manually were observed in 13.0% in mode 1 and in 19.1% in mode 2. CONCLUSIONS: The data indicate that impedance-controlled CPAP (APAP(FOT)) allows adequate treatment of OSAS patients at significantly lower pressures as compared with manually titrated pressure. Differences between the two modes are only minor.

Adult↗
PubMed2000

Comparison of assays for anti-endomysial and anti-transglutaminase antibodies for diagnosis of pediatric celiac disease.

BACKGROUND: Anti-endomysial antibodies are sensitive and specific markers for celiac disease. This antibody has recently been identified as an antibody to tissue transglutaminase, an enzyme that cross-links and stabilizes extracellular matrix proteins. OBJECTIVES: To evaluate the clinical usefulness of an enzyme-linked immunoassay for anti-transglutaminase antibodies, and to compare the results with those of AEA, the current gold standard serological test for celiac disease. METHODS: Serum samples were collected from 33 patients with biopsy-proven celiac disease and AEA tests were performed. Control samples for anti-transglutaminase were obtained from 155 patients. An ELISA test for immunoglobulin A anti-transglutaminase utilizing guinea pig liver transglutaminase was developed and performed on all sera. Cutoff values for the test were performed using logistic regression and receiver operating curves analysis. RESULTS: An optical density cutoff value of 0.34 was established for the assay. The mean value was 0.18 +/- 0.19 optical density for controls, and 1.65 +/- 1.14 for patients with celiac disease (P < 0.001). Sensitivity and specificity of the assay were both 90%, while AEA had a sensitivity and specificity of 100% and 94%, respectively. CONCLUSIONS: A tissue transglutaminase-based ELISA test is both sensitive and specific for detection of celiac disease.

Analysis of Variance↗
PubMed1999

Rapid emotional face processing in the human right and left brain hemispheres: an ERP study.

Imaging work has begun to elucidate the spatial organization of emotions; the temporal organization, however, remains unclear. Adaptive behavior relies on rapid monitoring of potentially salient cues (typically with high emotional value) in the environment. To clarify the timing and speed of emotional processing in the two human brain hemispheres, event-related potentials (ERPs) were recorded during hemifield presentation of face images. ERPs were separately computed for disliked and liked faces, as individually assessed by postrecording affective ratings. After stimulation of either hemisphere, personal affective judgements of face images significantly modulated ERP responses at early stages, 80-116 ms after right hemisphere and 104-160 ms after left hemisphere stimulation. This is the first electrophysiological evidence for valence-dependent, automatic, i.e. pre-attentive emotional processing in humans.

Adult↗
PubMed1999

Low resolution brain electromagnetic tomography (LORETA) functional imaging in acute, neuroleptic-naive, first-episode, productive schizophrenia.

Functional imaging of brain electrical activity was performed in nine acute, neuroleptic-naive, first-episode, productive patients with schizophrenia and 36 control subjects. Low-resolution electromagnetic tomography (LORETA, three-dimensional images of cortical current density) was computed from 19-channel electroencephalographic (EEG) activity obtained under resting conditions, separately for the different EEG frequencies. Three patterns of activity were evident in the patients: (1) an anterior, near-bilateral excess of delta frequency activity; (2) an anterior-inferior deficit of theta frequency activity coupled with an anterior-inferior left-sided deficit of alpha-1 and alpha-2 frequency activity; and (3) a posterior-superior right-sided excess of beta-1, beta-2 and beta-3 frequency activity. Patients showed deviations from normal brain activity as evidenced by LORETA along an anterior-left-to-posterior-right spatial axis. The high temporal resolution of EEG makes it possible to specify the deviations not only as excess or deficit, but also as inhibitory, normal and excitatory. The patients showed a dis-coordinated brain functional state consisting of inhibited prefrontal/frontal areas and simultaneously overexcited right parietal areas, while left anterior, left temporal and left central areas lacked normal routine activity. Since all information processing is brain-state dependent, this dis-coordinated state must result in inadequate treatment of (externally or internally generated) information.

Acute Disease↗
PubMed1999

A deviant EEG brain microstate in acute, neuroleptic-naive schizophrenics at rest.

Momentary brain electric field configurations are manifestations of momentary global functional states of the brain. Field configurations tend to persist over some time in the sub-second range ("microstates") and concentrate within few classes of configurations. Accordingly, brain field data can be reduced efficiently into sequences of re-occurring classes of brain microstates, not overlapping in time. Different configurations must have been caused by different active neural ensembles, and thus different microstates assumably implement different functions. The question arises whether the aberrant schizophrenic mentation is associated with specific changes in the repertory of microstates. Continuous sequences of brain electric field maps (multichannel EEG resting data) from 9 neuroleptic-naive, first-episode, acute schizophrenics and from 18 matched controls were analyzed. The map series were assigned to four individual microstate classes; these were tested for differences between groups. One microstate class displayed significantly different field configurations and shorter durations in patients than controls; degree of shortening correlated with severity of paranoid symptomatology. The three other microstate classes showed no group differences related to psychopathology. Schizophrenic thinking apparently is not a continuous bias in brain functions, but consists of intermittent occurrences of inappropriate brain microstates that open access to inadequate processing strategies and context information

Adult↗
PubMed1999

Single-dose piracetam effects on global complexity measures of human spontaneous multichannel EEG.

Global complexity of 47-channel resting electroencephalogram (EEG) of healthy young volunteers was studied after intake of a single dose of a nootropic drug (piracetam, Nootropil UCB Pharma) in 12 healthy volunteers. Four treatment levels were used: 2.4, 4.8, 9.6 g piracetam and placebo. Brain electric activity was assessed through Global Dimensional Complexity and Global Omega-Complexity as quantitative measures of the complexity of the trajectory of multichannel EEG in state space. After oral ingestion (1-1.5 h), both measures showed significant decreases from placebo to 2.4 g piracetam. In addition, Global Dimensional Complexity showed a significant return to placebo values at 9.6 g piracetam. The results indicate that a single dose of piracetam dose-dependently affects the spontaneous EEG in normal volunteers, showing effects at the lowest treatment level. The decreased EEG complexity is interpreted as increased cooperativity of brain functional processes.

Adult↗
PubMed1999

Affective attitudes to face images associated with intracerebral EEG source location before face viewing.

We investigated whether different, personality-related affective attitudes are associated with different brain electric field (EEG) sources before any emotional challenge (stimulus exposure). A 27-channel EEG was recorded in 15 subjects during eyes-closed resting. After recording, subjects rated 32 images of human faces for affective appeal. The subjects in the first (i.e., most negative) and fourth (i.e., most positive) quartile of general affective attitude were further analyzed. The EEG data (mean=25+/-4. 8 s/subject) were subjected to frequency-domain model dipole source analysis (FFT-Dipole-Approximation), resulting in 3-dimensional intracerebral source locations and strengths for the delta-theta, alpha, and beta EEG frequency band, and for the full range (1.5-30 Hz) band. Subjects with negative attitude (compared to those with positive attitude) showed the following source locations: more inferior for all frequency bands, more anterior for the delta-theta band, more posterior and more right for the alpha, beta and 1.5-30 Hz bands. One year later, the subjects were asked to rate the face images again. The rating scores for the same face images were highly correlated for all subjects, and original and retest affective mean attitude was highly correlated across subjects. The present results show that subjects with different affective attitudes to face images had different active, cerebral, neural populations in a task-free condition prior to viewing the images. We conclude that the brain functional state which implements affective attitude towards face images as a personality feature exists without elicitors, as a continuously present, dynamic feature of brain functioning.

Adult↗
PubMed1999

Aetiology and clinical signs of bacterial meningitis in children admitted to Goroka Base Hospital, Papua New Guinea, 1989-1992.

Children aged 1-59 months admitted to Goroka Base Hospital with signs suggestive of meningitis were recruited to determine what proportion of such children have clinical or bacterial meningitis and to investigate the bacterial aetiology. A laboratory classification of definite, probable, possible, indeterminate and no meningitis was established. Thirty per cent of 697 children had a final clinical diagnosis of meningitis, 12% had culture-proven bacterial meningitis (case fatality rate 34%) and 10% had probable or possible meningitis. Inability to feed, vomiting, drowsiness, "staring eyes" and haemoglobin < 9 g/dl in addition to the classical signs of meningitis were associated with increased mortality. Isolates from cerebrospinal fluid were 62 pneumococci, 22 Haemophilus influenzae type b (Hib) and one Neisseria meningitidis. Including blood culture-proven and antigen-proven Hib disease, Hib and pneumococci accounted for 44% and 46% of bacterial meningitis, respectively, and 23% of pneumococci were intermediately resistant to penicillin. Inability to feed, bulging fontanelle, convulsions in young children, neck stiffness, fever and "staring eyes" were all independently associated with bacterial meningitis. Conjugate Hib vaccine must be given to infants as early as possible. Conjugate pneumococcal vaccines, maternal immunization with 23-valent vaccine and pneumococcal protein vaccines are under investigation for prevention of pneumococcal disease.

Age Distribution↗
PubMed1999

Bacterial and viral etiology of severe infection in children less than three months old in the highlands of Papua New Guinea.

OBJECTIVE: Determine the bacterial and viral etiology of severe infection in young Papua New Guinean infants as part of a multicenter study in four developing countries aimed at improving case management guidelines. METHODS: Between March, 1991, and April, 1993, children aged <3 months were recruited at the outpatient department of Goroka Base Hospital, Papua New Guinea (PNG). Children with pre-defined inclusion criteria were enrolled, a history was taken and clinical examination was performed. Blood and urine were collected from children with signs suggestive of severe disease together with eye, umbilical and pernasal swabs as appropriate. Nasopharyngeal aspirates (NPAs) were collected from children with and without signs of severe disease for identification of viruses and Chlamydia trachomatis by direct fluorescent antibody staining. RESULTS: 3280 infants were triaged and 2168 enrolled, among whom 968 had signs suggestive of severe disease. Group A Streptococcus (Streptococcus pyogenes) and Staphylococcus aureus were the most important bacterial pathogens isolated from children < 1 month old with severe infections, and Streptococcus pneumoniae, S. pyogenes and Staphylococcus aureus were most important in older children. Of 292 eye swabs 19 (7%) grew Neisseria gonorrhoeae. Of 116 umbilical swabs 51 (44%) grew S. pyogenes and 45 (39%) grew Staphylococcus aureus. Respiratory syncytial virus was the most important viral cause of acute lower respiratory infection. CONCLUSIONS: S. pyogenes, S. pneumoniae and Staphylococcus aureus are important causes of severe infection in young children in the PNG highlands. It is necessary to improve access to clean water, promote hand-washing in the hospital and at home and investigate further the use of maternal immunization for the prevention of severe disease in young infants.

Bacteria↗
PubMed1999

High rates of Chlamydia trachomatis infections in young Papua New Guinean infants.

OBJECTIVE: Determine the importance of Chlamydia trachomatis in the etiology of severe infection in young Papua New Guinean infants. METHODS: Between March, 1991, and April, 1993, children <3 months old were recruited as outpatients at Goroka Base Hospital, Papua New Guinea, as part of a multicenter study in four developing countries. Children with predefined inclusion criteria were enrolled. C. trachomatis was identified by direct fluorescent antibody staining in nasopharyngeal aspirates (NPAs) collected from children with and without signs of severe disease and eye swabs from children with and without conjunctivitis. Two to three radiologists read chest radiographs without knowledge of clinical and laboratory findings. RESULTS: Of 3280 outpatients seen 2168 enrolled, 955 NPAs were tested for C. trachomatis and 549 chest radiographs were read. Of 210 eye swabs from children with conjunctivitis 57% were positive for C. trachomatis compared with 8% from 167 children with no conjunctivitis. The prevalence of C. trachomatis in NPAs was 9% in asymptomatic children and 18 and 33% in children with nonsevere or severe pneumonia, respectively. C. trachomatis in NPAs was strongly associated with clinically severe pneumonia [odds ratio (OR), 2.91], reduced arterial oxygen saturation (OR 2.58) and radiographic evidence of pneumonia (OR 5.84) and was also associated with pneumococcal bacteremia (OR 3.48). CONCLUSIONS: In Papua New Guinea Chlamydia must be considered as a cause when treating pneumonia in infants, and effective treatment and prevention of sexually transmitted diseases are urgently needed for a number of reasons, including the need to curb high rates of chlamydial infection in women and infants.

Chlamydia Infections↗