Biomedical subjects

Peter Schneider

Publications and source records attributed to Peter Schneider.

At least 19 recordsLinked to original sources

PubMed2006

Dissociated lateralization of transient and sustained blood oxygen level-dependent signal components in human primary auditory cortex.

Among other auditory operations, the analysis of different sound levels received at both ears is fundamental for the localization of a sound source. These so-called interaural level differences, in animals, are coded by excitatory-inhibitory neurons yielding asymmetric hemispheric activity patterns with acoustic stimuli having maximal interaural level differences. In human auditory cortex, the temporal blood oxygen level-dependent (BOLD) response to auditory inputs, as measured by functional magnetic resonance imaging (fMRI), consists of at least two independent components: an initial transient and a subsequent sustained signal, which, on a different time scale, are consistent with electrophysiological human and animal response patterns. However, their specific functional role remains unclear. Animal studies suggest these temporal components being based on different neural networks and having specific roles in representing the external acoustic environment. Here we hypothesized that the transient and sustained response constituents are differentially involved in coding interaural level differences and therefore play different roles in spatial information processing. Healthy subjects underwent monaural and binaural acoustic stimulation and BOLD responses were measured using high signal-to-noise-ratio fMRI. In the anatomically segmented Heschl's gyrus the transient response was bilaterally balanced, independent of the side of stimulation, while in opposite the sustained response was contralateralized. This dissociation suggests a differential role at these two independent temporal response components, with an initial bilateral transient signal subserving rapid sound detection and a subsequent lateralized sustained signal subserving detailed sound characterization.

Acoustic Stimulation↗

PubMed2006

Venturia inaequalis-inhibiting Diels-Alder adducts from Morus root bark.

In organic apple orcharding there is a continuous need for natural fungicides effective against Venturia inaequalis (Cooke) Winter, the causal agent of apple scab. In this study an in vitro assay is presented for determining the germination inhibitory potential of extracts and pure compounds. From a screening of plant extracts, the methanol extract of Morus root bark revealed distinct V. inaequalis inhibiting qualities, which were subjected to a bioguided fractionation. Among the isolated metabolites [moracins M (1), O/P (2), kuwanon L (3), and sanggenons D (4), B (5), G (6), O (7), E (8), and C (9)] all the Diels-Alder adducts (3-9) showed an antifungal activity with IC50 values between 10 and 123 microM. The in vitro activity of the most active fraction (A5, IC50 39.0 +/- 4.2 microg/mL) was evaluated in vivo, confirming a distinct antifungal activity against V. inaequalis for the tested natural material.

Antifungal Agents↗

PubMed2006

Transient Th1/Th2 disbalance indicates postoperative effusions and edema after cardiopulmonary bypass in children.

BACKGROUND: Cardiac surgery with cardiopulmonary bypass (CPB) induces substantial release of IL-10, indicating increased Th2 cell response. Therefore, in this study, we wanted to verify if this response is due to CPB or surgical trauma, and to study its relation to postoperative effusions and edema (POEE) in children. METHODS: Th1/Th2 reaction was monitored in children undergoing cardiovascular surgery with (n = 75) and without CPB (n = 29). RESULTS: Surgery with CPB compared to surgery without CPB induced a transient shift towards Th2. Elevated Th2 response was related to increased vascular permeability and POEE. CONCLUSION: The immune suppression/Th2 response is typical for CPB, and at intermediate level is tolerable but at high level could be adverse for the patients.

Adolescent↗

PubMed2006

Intracardiac thrombus causing systemic embolism in a child with idiopathic ventricular tachycardia and heterozygous activated protein C resistance.

Systemic embolism in childhood is rare but often disastrous. Most often the concomitant occurrence of more than one prothrombotic factor is responsible for the acute event. We report on a child in whom an intracardiac thrombus embolized into the descending aorta resulting in subtotal occlusion. Causative for thrombus formation was an idiopathic ventricular tachycardia and a heterozygous activated protein C resistance, both previously unknown. Immediate surgical thrombectomy was successful without sequelae. Antithrombotic and antiarrhythmispioproptylactic treatment was started afterwards. We suggest that in cases of longstanding or repeated tachycardia and in children after thromboembolic events diagnostic work-up for thrombophilia should be undertaken.

Child, Preschool↗

PubMed2005

Structural and functional asymmetry of lateral Heschl's gyrus reflects pitch perception preference.

The relative pitch of harmonic complex sounds, such as instrumental sounds, may be perceived by decoding either the fundamental pitch (f0) or the spectral pitch (fSP) of the stimuli. We classified a large cohort of 420 subjects including symphony orchestra musicians to be either f0 or fSP listeners, depending on the dominant perceptual mode. In a subgroup of 87 subjects, MRI (magnetic resonance imaging) and magnetoencephalography studies demonstrated a strong neural basis for both types of pitch perception irrespective of musical aptitude. Compared with f0 listeners, fSP listeners possessed a pronounced rightward, rather than leftward, asymmetry of gray matter volume and P50m activity within the pitch-sensitive lateral Heschl's gyrus. Our data link relative hemispheric lateralization with perceptual stimulus properties, whereas the absolute size of the Heschl's gyrus depends on musical aptitude.

Acoustic Stimulation↗

PubMed2005

The route of administration (oral vs intravenous) does not influence dose or outcome in Graves' disease and unifocal autonomy.

PURPOSE: In a prospective randomised study, we investigated the influence of the route of administration of radioiodide on dosimetry and therapy outcome. METHODS: Fifty-four patients suffering from Graves' disease (GD) and 60 patients with unifocal autonomy (UA) participated in the study and were randomly treated with either orally or intravenously administered radioiodide. Pretherapeutic dosimetry was based on single uptake measurements with a calibrated uptake probe system. The radioiodine kinetics during hospitalisation was assessed by daily bedside uptake measurements. Therapeutic dose was determined by half-life and thyroid uptake at the time of discharge using the same uptake probe as for the radioiodine test. RESULTS: No improvement in accuracy of dosimetry was achieved when radioiodide was administered intravenously. Mean therapeutic doses were identical following intravenous or oral administration. Variation in the achieved dose was slightly higher in the patients receiving oral administration, this being attributable to larger deviations in discrete activities of the capsules administered as compared with the values determined by dosimetry. No differences according to treatment modality were found with regard to therapeutic outcome. Eighty-seven patients attended 6-month follow-up after therapy. In the UA group, successful treatment, defined as a normal or elevated TSH level, was observed in 94% of patients after oral administration and in 80% after intravenous administration; corresponding figures in the GD group were 68% and 65%. CONCLUSION: The causes of individual differences between targeted and therapeutically achieved doses remain undetermined. Variations in the bioavailability of radioiodide or other parameters affecting thyroid status may be involved, and further investigations are needed to clarify this.

Administration, Oral↗

PubMed2005

Computer-based training in two-dimensional echocardiography using an echocardiography simulator.

Two-dimensional (2D) echocardiography is a user-dependent technique that poses some inherent problems to the beginner. The first problem for beginners is spatial orientation, especially the orientation of the scan plane in reference to the 3-dimensional (3D) geometry of the heart. The second problem for beginners is steering of the ultrasound probe. We have designed a simulator to teach these skills. On a computer screen a side-by-side presentation of a 3D virtual reality scene on the right side and a 2D echocardiographic view on the left side is given. The virtual scene consists of a 3D heart and an ultrasound probe with scan plane. The 2D echocardiographic image is calculated from 3D echocardiographic data sets that are registered with the heart model to achieve spatial and temporal congruency. The displayed 2D echocardiographic image is defined and controlled by the orientation of the virtual scan plane. To teach hand-eye coordination we equipped a dummy transducer with a 3D tracking system and placed it on a dummy torso. We have evaluated the usability of the simulator in an introductory course for final-year medical students. The simulator was graded realistic and easy to use. According to a subjective self-assessment by a standardized questionnaire the aforementioned skills were imparted effectively.

Adult↗

PubMed2005

Early post-convulsive prolongation of QT time in children.

AIM: An important differential diagnosis of seizures in childhood is the long QT syndrome. Childhood epilepsy occurs about 400 times more often than long QT syndrome. We had observed children with slight post-convulsive prolongation of QT time more often than the reported incidence of long QT syndrome. We therefore conducted a prospective study to define the characteristics of post-convulsive prolongation of QT time in children. METHODS: We investigated 30 consecutive infants and children (3 mo to 14 y) within 2 h after seizures. A follow-up ECG was obtained 1-9 d later. We also obtained ECGs from 30 healthy age- and gender-matched controls. We calculated the QT interval corrected for heart rate (QTc) by Bazett's formula in leads II, V5, V6, QT dispersion and the number of notched T waves. RESULTS: We found a QTc interval of more than 440 ms in one or more leads in the first ECG in seven of 30 infants and children compared to 1 of 30 in the follow-up ECG (p=0.0003) and two of 30 in the healthy controls (p=0.14). Average QTc was higher for all leads in the first ECG. This was statistically significant in leads II (414 vs 402 ms, p=0.008), V5 (416 vs 404 ms, p=0.002) and V6 (415 vs 399 ms, p=0.001). Compared to healthy controls, QT dispersion was slightly larger in the early post-convulsive ECG (36 vs 31 ms, p=0.03). Notched T waves occurred more frequently in the early compared to the late post-convulsive ECGs (p=0.009). CONCLUSION: Slight to moderate post-convulsive prolongation of the QT interval is not rare but transient in paediatric patients.

Adolescent↗

PubMed2005

Structural, functional, and perceptual differences in Heschl's gyrus and musical instrument preference.

The musical pitch of harmonic complex sounds, such as instrumental sounds, is perceived primarily by decoding either the fundamental pitch (keynote) or spectral aspects of the stimuli, for example, single harmonics. We divided 334 professional musicians, including symphony orchestra musicians, 75 amateur musicians, and 54 nonmusicians, into either fundamental pitch listeners or spectral pitch listeners. We observed a strong correlation between pitch perception preference and asymmetry of brain structure and function in the pitch-sensitive lateral areas of Heschl's gyrus (HG), irrespective of musical ability. In particular, fundamental pitch listeners exhibited both larger gray matter volume measured using magnetic resonance imaging (MRI) and enhanced P50m activity measured using magnetoencephalography (MEG) in the left lateral HG, which is sensitive to rapid temporal processing. Their chosen instruments were percussive or high-pitched instruments that produce short, sharp, or impulsive tones (e.g., drums, guitar, piano, trumpet, or flute). By contrast, spectral pitch listeners exhibited a dominant right lateral HG, which is known to be sensitive to slower temporal and spectral processing. Their chosen instruments were lower-pitched melodic instruments that produce rather sustained tones with characteristic changes in timbre (e.g., bassoon, saxophone, french horn, violoncello, or organ). Singers also belonged to the spectral pitch listeners. Furthermore, the absolute size of the neural HG substrate depended strongly on musical ability. Overall, it is likely that both magnitude and asymmetry of lateral HG, and the related perceptual mode, may have an impact on preference for particular musical instruments and on musical performance.

Acoustic Stimulation↗

PubMed2005

Radiosynovectomy in rheumatology, orthopedics, and hemophilia.

Radiosynovectomy (RSV) is a local intraarticular injection of radionuclides in colloidal form for radiotherapy. First used by Fellinger et al. in 1952, the technique has now been applied for more than 50 y for treatment of resistant synovitis of individual joints after failure of long-term systemic pharmacotherapy and intraarticular steroid injections. RSV relieves pain and inflammation from rheumatoid arthritis (RA), for which it initially was used, and is accepted as an alternative to surgical synovectomy in cases of RA or other inflammatory arthropathies such as osteoarthritis and hemophiliac arthropathy. A good understanding of the clinical pathophysiology of the disease processes is mandatory, and close interdisciplinary collaboration with other clinicians who diagnose and treat patients is strongly suggested. Reported success rates range from 40% to 90% for the different joints and underlying diseases. A few well-designed prospective double-blind trials have evaluated the efficacy of RSV and justified the procedure as a viable option for treating chronic synovitis in RA or secondary to inflammatory arthropathies. In comparison with surgical synovectomy, RSV produces equivalent results, costs less, allows the patient to remain ambulatory, and is repeatable. RSV has to be considered the initial procedure of choice for the treatment of patients with hemarthrosis in hemophilia. In addition, local instillation of radiopharmaceuticals can effectively reduce effusions after implantation of a prosthesis.

Animals↗

PubMed2004

Somatostatin receptor subtype 2 is expressed by supratentorial primitive neuroectodermal tumors of childhood and can be targeted for somatostatin receptor imaging.

PURPOSE: Although gliomas predominate among central nervous system (CNS) neoplasms in adulthood, embryonal tumors are the most common malignant brain tumors in children. Despite novel treatment approaches, including improved radiotherapy and high-dose chemotherapy, survival rates remain unsatisfactory. The timely diagnosis of residual or recurrent embryonal CNS tumors and thus the earliest possible time point for intervention is often hampered by inaccuracies of conventional imaging techniques. Novel and refined imaging methodologies are urgently needed. EXPERIMENTAL DESIGN: We have previously demonstrated the use of somatostatin receptor imaging (SRI) in the diagnosis of recurrent and residual medulloblastomas. Here, we evaluated somatostatin receptor type 2 (sst(2)) expression using an antibody in an array of CNS tumors of childhood. Eight high-grade gliomas, 4 atypical teratoid/rhabdoid tumors, 7 supratentorial primitive neuroectodermal tumors (stPNET), 1 medulloepithelioma (ME), and 8 ependymomas were screened. Tumors positive in vitro were additionally analyzed in vivo using SRI. RESULTS: Abundant expression of somatostatin receptor type 2 in stPNET, a ME, and ependymomas warranted in vivo imaging of 7 stPNET, 1 rhabdomyosarcoma, 3 ependymomas, 1 ME, and 1 glioblastoma. Although SRI was positive in 6/7 stPNET, 1 rhabdomyosarcoma, and 1 ME, none of the ependymomas nor the glioblastoma could be imaged using SRI. In selected cases SRI was more sensitive in the detection of relapse than conventional imaging by magnetic resonance imaging and computed tomography. CONCLUSIONS: SRI should be considered in the evaluation of residual or recurrent embryonal CNS tumors, especially stPNET. The strengths of SRI lie in the differentiation of reactive tissue changes versus residual or recurrent tumor, the detection of small lesions, and possibly in the distinction of stPNET from gliomas.

Central Nervous System Neoplasms↗

PubMed2004

The EDNAP mitochondrial DNA population database (EMPOP) collaborative exercises: organisation, results and perspectives.

This paper presents an overview of the organisation and the results of the collaborative exercises (CE) of the European DNA Profiling (EDNAP) Group's mitochondrial DNA population database project (EMPOP). The aim of the collaborative exercises was to determine whether uniformity of mtDNA sequencing results could be achieved among different laboratories. These were asked to sequence either the complete mtDNA control region or the two hypervariable regions HVI (16024-16365) and HVII (73-340) from DNA extracts, buccal swabs or bloodstains, proceeding in accordance with the protocol and strategies used in each individual laboratory. The results of the collaborative exercises were employed to identify possible sources of errors that could arise during the analysis and interpretation of mtDNA profiles. These findings were taken as a basis to tentatively make suitable arrangements for the construction of a high quality mtDNA database. One hundred fifty mtDNA profiles were submitted to the evaluating laboratory, and disaccording profiles were classified into four groups corresponding to the source of error: clerical errors, sample mix-ups, contaminations and discrepancies with respect to the mtDNA nomenclature. Overall, 14 disaccording haplotypes (16 individual errors) were observed. The errors included 10 clerical errors, 3 interpretation problems, 2 cases of sample mix-up and 1 case of point heteroplasmic mixture, where the 2 sequencing reactions brought inconsistent base calls. This corresponds to an error rate of 10.7% in a virtual mtDNA database consisting of the collaborative exercise results. However, this estimate is still conservative compared to conclusions drawn by authors of meanwhile numerous publications critically reviewing published mtDNA population databases. Our results and earlier published concerns strongly emphasize the need for appropriate safety regulations when mtDNA profiles are compiled for database purposes in order to accomplish the high standard required for mtDNA databases that are used in the forensic context.

Clinical Laboratory Techniques↗

PubMed2004

[Piercing and tattoos in patients with congenital heart disease -- is it a problem?].

Piercing and tattooing enjoy widespread popularity in modern society. Patients with congenital heart disease are at elevated risk for infective endocarditis. However, it is not yet known whether piercing and tattooing are dangerous for these patients.A search of the literature provided 10 published cases of infective endocarditis after piercing or tattooing. Affected patients were adolescents or young adults ranging in age from 13 to 30 years (5 male, 5 female). Four of the patients had a known cardiac risk factor for endocarditis (bicuspid aortic valve, postoperative trans-position of the great arteries, postoperative coarctation, postoperative aortic valve stenosis). Piercing preceded endocarditis in 9 cases (4 times mouth, 2 ear, 1 nose, 1 breast, 1 navel), one tattoo. The following agents were isolated: S. aureus in 4 cases, 2 S. epidermidis, 1 Str. viridans, 1 Neisseria mucosa, 1 Haemophilus aphrophilus, 1 Haemophilus parainfluenzae. All patients were treated with antibiotics. Six patients underwent cardiac surgery (5 of them valve replacement). Patients with congenital heart disease constitute less than 1% of the population. Thus, they are clearly overrepresented in the published literature. Epidemiologic conclusions are not possible from these data. However, patients with congenital heart disease and their parents should be strongly advised against piercing and tattooing with regard to the risk of infective endocarditis.

Adolescent↗

PubMed2004

Autologous stem cell transplantation for systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is responsive to treatment with immunosuppressives and steroids, but often pursues a relapsing or refractory course resulting in increasing incapacity and reduced survival. Autologous stem cell transplantation (ASCT) following immunoablative chemotherapy is a newer therapy for autoimmune disease of potential use in severe SLE. A retrospective registry survey was carried out by the European Blood and Marrow Transplant and European League Against Rheumatism (EBMT/EULAR) registry. Data was collected from 53 patients with SLE treated by ASCT in 23 centres. Disease duration before ASCT was 59 (2-155) months (median, range), 44 (83%) were female, and median age was 29 (9-52) years. At the time of ASCT a median of seven American College of Rheumatology (ACR) diagnostic criteria for SLE were present (range 2-10) and 33 (62%) had nephritis. Peripheral blood stem cells were mobilized with cyclophosphamide and granulocyte colony stimulating factor in 93% of cases. Ex vivo CD34 stem cell selection was performed in 42% of patients. Conditioning regimens employed cyclophosphamide in 84%, anti-thymocyte globulin in 76% and lymphoid irradiation in 22%. The mean duration of follow-up after ASCT was 26 (0-78) months. Remission of disease activity (SLEDAI < 3) was seen in 33/50 (66%; 95%CI 52-80) evaluable patients by six months, of which 10/31 (32%; 95%CI 15-50) subsequently relapsed after six (3-40) months. Relapse was associated with negative anti-double stranded DNA (anti-dsDNA) antibodies before ASCT (P = 0.007). There were 12 deaths after 1.5 (0-48) months, of which seven (12%; 95%CI 3-21) were related to the procedure. Mortality was associated with a longer disease course before ASCT (P = 0.036). In conclusion, this registry study demonstrates the efficacy of ASCT for remission induction of refractory SLE, although mortality appeared high. The safety of this procedure is likely to be improved by patient selection and choice of conditioning regimen. The return of disease activity in one-third of patients might be reduced by long-term immunosuppressive therapy post-ASCT.

Adolescent↗

PubMed2003

Iclaprim, a novel diaminopyrimidine with potent activity on trimethoprim sensitive and resistant bacteria.

Iclaprim, a new selective dihydrofolate inhibitor was synthesized based on rational drug design. Iclaprim's interaction with a resistant Staphylococcus aureus dihydrofolate reductase (DHFR) is outlined in comparison to trimethoprim (TMP). This compound is active against methicillin, TMP and vancomycin resistant strains. Arpida Ltd. is developing Iclaprim for serious hospital infections from Gram-positive pathogens and respiratory tract infections.

Animals↗

PubMed2003

Protein-losing enteropathy in patients with Fontan circulation: is it triggered by infection?

INTRODUCTION: Protein-losing enteropathy (PLE) is a recognised complication of the Fontan circulation. Its pathogenesis is not fully understood, however, and it is unclear why its onset occurs months or even years after Fontan surgery. PATIENTS: We report a 4.5-year-old girl with Fontan circulation who developed PLE almost 1 year after surgery. At the time of onset the patient had rotavirus enteritis and streptococcal tonsillitis. We have reviewed the records of seven other patients with longstanding PLE. In six of these patients we identified infections at the onset of symptoms. None of our patients had evidence of opportunistic infection. DISCUSSION AND CONCLUSION: The immune system of patients with PLE is compromised, but reports on recurrent opportunistic infections are rare. The present observations suggest that infection and inflammation may be associated with the onset of PLE. The mechanism of how infection may trigger PLE warrants further investigation.

Child↗

PubMed2003

Protein-losing enteropathy after fontan surgery: is assessment of risk patients with immunological data possible?

BACKGROUND: Protein-losing enteropathy (PLE) is a late complication of the Fontan type surgery for univentricular heart characterized by massive enteric protein loss. The pathogenesis of PLE is not fully understood, and it is unclear why the onset of PLE varies widely and occurs months or even years after surgery. Besides characteristic laboratory findings, a typical cellular feature concerns the almost selective loss of CD4(+) lymphocytes at an only slightly changed CD8(+) lymphocyte count. The present pilot study aimed to test whether immunological or laboratory parameters differ in patients at risk for PLE. METHODS: From children (n = 15) with Fontan type circulation, extensive cellular, humoral, and clinical laboratory data were analyzed. Patients without enteric protein loss (group I, n = 8), with transient phases of enteric protein loss in the absence of gastric infections (group II, n = 6), and one PLE patient (group III) were distinguished. The 90 data columns obtained in phases with normal serum protein levels were compared. RESULTS: Clear differences were apparent between patients prior to PLE onset (group III), patients that in at least one occasion exhibited PLE signs (group II), and patients without detectable PLE signs (group I). The most discriminatory parameters between the three patient groups were NK and CD8(+)TCRalphabeta(+), CD8(+)TCRgammadelta(+) cell counts, including sL-selectin, IgE, and Ca(2+) (average recognition index = 91.5%, negative/positive prediction/sensitivity/specificity > 83%). CONCLUSIONS: The results of this study seem to provide access to the early detection of PLE patients.

Adolescent↗

PubMed2003

[Staffing levels in medical radiation physics in radiation therapy in Germany. Summary of a questionnaire].

To get a general idea of the actual staffing level situation in medical radiation physics in 1999 a survey was carried out by the task-group "Personalbedarf" of Deutsche Gesellschaft für Medizinische Physik (DGMP) among all DGMP-members who are active in this field. Main components for equipment and activities are defined in Report 8 and 10 of DGMP for staffing requirements in medical radiation physics. 322 forms were sent out, 173 of them have been evaluated. From the answers regarding equipment and activities numbers for staff are calculated by the methods given in Report 8 and 10 for this spot check target and compared with effective staffing levels. The data of the spot check are then extrapolated on total Germany. The result is a calculated deficit of 865 medical physicists for the whole physics staff, 166 of them in radiation therapy. From the age distribution of DGMP-members and the calculated deficit resulted a training capacity of about 100 medical physicists at all per year (19 in radiation therapy) if the deficit shall be cut back in 10 years.

Austria↗