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Biomedical subjects

M Riedel

Publications and source records attributed to M Riedel.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Disorders of the pulmonary lymphatic system].

The pulmonary lymphatic system plays an important role in lung perfusion homeostasis. Congenital errors of lymphatic vessel development lead to primary pulmonary lymphatic disorders (lymphangiomas, lymphangiectasis, lymphatic dysplasia syndromes). Acquired disorders of the pulmonary lymphatic system occur in a variety of clinical settings (ranging from trauma to cancer) and may lead to serious pulmonary disease. Because of their scarcity and confusing and inconsistent use of terminology, these conditions are often misdiagnosed. Their management is difficult.

Diagnosis, Differential↗
PubMed2001

Increased titers of antibodies against streptococcal M12 and M19 proteins in patients with Tourette's syndrome.

It has been suggested that a post-streptococcal autoimmune process may be involved in the pathogenesis of a subgroup of children with tics and obsessive-compulsive symptoms (PANDAS). Elevated antibody titers against streptococcal antigens have also been described in adult patients suffering from Tourette's syndrome (TS). In order to characterise further streptococcal antigens, we focussed on M proteins. M proteins are a major virulence factor of group A streptococci and known to evoke an immunologic cross-reaction with diverse epitopes of human tissue including brain tissue. Therefore, antibodies against M proteins may play a role in the pathophysiology of at least a subgroup of TS patients. Antibodies against M proteins were studied in 25 adult patients suffering from TS and 25 healthy controls after careful medical examination. The antibody titers against the peptides M1, M4, M6, M12 and M19 were estimated by ELISA. Our results show increased titers of antibodies against the streptococcal M12 and M19 proteins in TS patients as compared with controls, while antibody titers against M1, M4 and M6 did not differ between the TS and control groups. Elevated serum titers of antibodies against M12 and M19 proteins support the view that a streptococcus-induced autoimmune process may be involved in TS. The finding of a possible autoimmune origin of TS has implications for both pathophysiology and future therapeutic strategies.

Adolescent↗
PubMed2001

P300 and symptom improvement in schizophrenia.

RATIONALE: A reduced amplitude of the auditory evoked P300 was interpreted as a trait marker of schizophrenia but reports about correlations between schizophrenic psychopathology and P300 amplitude indicate also a state character. OBJECTIVES: To shed light upon these trait and state aspects a longitudinal study was performed to investigate the influence of symptom improvement and atypical neuroleptics on the amplitudes of the P300 and their subcomponents. METHODS: P300 was recorded in 17 schizophrenic patients before and after 4 weeks under either clozapine or olanzapine in a double-blind controlled design. For comparison, 17 age- and sex-matched healthy subjects were investigated. Parietal and frontal P300 subcomponents were investigated separately using dipole source analysis. RESULTS: Schizophrenic patients had smaller parietal (temporo-basal dipole) but not frontal subcomponent amplitudes (temporo-superior dipole) than controls. For the whole sample subcomponent amplitudes did not change over 4 weeks despite clinical improvement but patients with a pronounced improvement of the PANSS positive score showed a slight enhancement of both subcomponents. This was not significant when the P300 amplitude was measured at a single electrode (Pz). No significant difference between clozapine and olanzapine concerning effects on P300 amplitudes were observed. CONCLUSIONS: The results indicate that P300 subcomponents are modulated by changes of positive but not by changes of negative symptoms or different neuroleptics. This result was obvious for P300 subcomponents but not for Pz electrode measurement, which may be due to a higher reliability of the dipole source activity. The results can be integrated into a hypothetical model containing two pathophysiological subgroups of schizophrenia.

Adult↗
PubMed2001

Protein adsorption and monocyte activation on germanium nanopyramids.

Germanium can form defect-free pyramidal islands on Si(1 0 0)-2 x 1 with a height of 15 nm and a width of 60 nm. Using chemical vapor deposition we have prepared substrates with different nanopyramid densities to study the impact on contact angles, protein adsorption and cell behavior. The advancing contact angle of a water droplet of millimeter size significantly raises with nanopyramid density. The dynamic contact angle measurements reveal that the substrate surface is highly hydrophilic. On such a surface the adsorption of hydrophilic proteins, i.e. albumin and globulin, is drastically increased by the presence of nanopyramids. More important, however, the globulin is inactive after adsorption on nanopyramid edges. This observation is supported by the cytokine release of IL-1beta and TNF-alpha of monocyte-like cell line U937. Consequently, the presence of nanopyramidal structures gives rise to less inflammatory reactions.

Adsorption↗
PubMed2001

The Th2-hypothesis of schizophrenia: a strategy to identify a subgroup of schizophrenia caused by immune mechanisms.

Immunologic findings in schizophrenia have been described for decades, but it was not possible to identify a pathogen until now. Most of these studies report immune abnormalities in a group of the investigated patients, but a distinct subgroup of schizophrenia with immune-related pathology has still not been characterized. In this paper we have integrated the most important immunologic data in schizophrenia research and hypothesize a shift to Th2-like immune reactivity in a subgroup of schizophrenic patients. Besides the immunological abnormalities, this subgroup is further characterized by more pronounced negative symptoms and poor therapy outcome. There is evidence that this subgroup might be caused by a prenatal viral infection.

Humans↗
PubMed2001

Extensive sampling improves preoperative bronchoscopic assessment of airway invasion by supracarinal esophageal cancer: a prospective study in 166 patients.

BACKGROUND: The utility of fiberoptic bronchoscopy in the preoperative assessment of patients with esophageal cancer has not been thoroughly investigated. More accurate staging could improve the design of clinical trials and avoid inappropriate surgical decisions in individual patients. STUDY OBJECTIVE: To evaluate the utility of bronchoscopy in the preoperative assessment of airway invasion by supracarinal esophageal cancer. DESIGN: We prospectively analyzed 220 bronchoscopies in 166 consecutive patients with supracarinal esophageal cancer and correlated the findings with operative results and survival. RESULTS: In 126 bronchoscopies (57.3%), no abnormal findings could be seen in the airways. Compared with histologic and cytologic results, the normal macroscopic appearance of the airways had a negative predictive value of 94.4%, but the positive predictive value of all macroscopic abnormalities for the diagnosis of airway invasion was low, particularly after radiation therapy. Endoluminal tumor mass, protrusion of the posterior tracheal wall, and signs of mucosal invasion were visible in 5.9%, 28.6%, and 4.1% of the bronchoscopies, respectively. However, in only 8.6% of the 220 bronchoscopies, cancer invasion was proved by biopsy or cytology. Bronchoscopy with biopsies and brush and washing cytology examinations was the sole decisive staging procedure, enabling the exclusion from surgery because of airway invasion in 18.1% of otherwise potentially operable patients, with an overall accuracy of 93.3% (95% confidence interval, 86.7 to 97.3%). The results of bronchoscopy were falsely negative in six patients, who all underwent surgery after neoadjuvant therapy. CONCLUSIONS: Fiberoptic bronchoscopy with systematic multiple biopsies and brush and washing cytology examinations is an accurate procedure in evaluating the possible invasion of supracarinal esophageal cancer into the airways. Macroscopic findings alone are not reliable; errors in sole bronchoscopic inspection would have resulted in operations that would be unlikely to help the patients or would have inappropriately excluded patients from surgery.

Adult↗
PubMed2001

[Non-thrombotic pulmonary embolisms].

In the absence of intracardiac or intrapulmonary shunts, the pulmonary microvasculature traps all embolized particles greater than 10 microns. In the vast majority of cases these emboli are venous thrombi which lodge in larger pulmonary arteries, resulting in obstructive phenomena rather than primarily being injurious to lung parenchyma. This review deals exclusively with nonthrombotic pulmonary embolism which involves substances that lodge predominantly in the pulmonary microvessels and cause a true endothelial and parenchymal injury, as well as obstructive phenomena. The article focuses on fat embolism, amniotic fluid embolism, gas embolism, septic emboli, and tumour pulmonary embolism.

Embolism, Air↗
PubMed2000

Origin of surface conductivity in diamond

Hydrogen-terminated diamond exhibits a high surface conductivity (SC) that is commonly attributed to the direct action of hydrogen-related acceptors. We give experimental evidence that hydrogen is only a necessary requirement for SC; exposure to air is also essential. We propose a mechanism in which a redox reaction in an adsorbed water layer provides the electron sink for the subsurface hole accumulation layer. The model explains the experimental findings including the fact that hydrogenated diamond is unique among all semiconductors in this respect.

Journal Article↗
PubMed2000

Digitized analysis of abnormal hand-motor performance in schizophrenic patients.

Many studies have shown a high prevalence of discrete neuromotor disturbances in schizophrenic patients. It was hypothesized that these disturbances are lateralized and reflect a neurodevelopmental disorder underlying schizophrenia. A new method for assessing subtle motor dysfunction and hemispheric asymmetries is the registration of hand movements with a digitizing tablet. Using this method, we studied hand-motor dysfunction and its lateralization in schizophrenics, as compared with healthy controls. All subjects (27 schizophrenic patients, 13 of them without neuroleptic medication, the others under neuroleptics; 31 healthy controls) drew super-imposed concentric circles. We computed kinematic parameters reflecting velocity and automatization to quantify neurological soft signs (NSS). The patients had significant impairments of regularity of repetitive hand movements, as compared with the healthy controls (F> or =5.35; p< or =0.024(*)). Comparing differences of left- and right-hand performance between patients and controls, we found longer stroke duration (F=(15,98); p=0.000***) and decreased automatization (F=18,14; p=0.000***), especially on the left side in schizophrenic patients. Measuring hand movements with a digitizing tablet is a sensitive method for assessing subtle motor dysfunction in schizophrenic patients, not reflected in the scores of clinical scales. Our findings show NSS in schizophrenic patients, independently of neuroleptics. Further, the hypothesis of lateralization of cerebral structures generating NSS towards the right hemisphere in schizophrenia is supported.

Adult↗
PubMed2000

Evidence for an association between a G-protein beta3-gene variant with depression and response to antidepressant treatment.

Abnormal signal transduction pathways have been implicated in the pathogenesis of bipolar disorder and major depression. G-proteins are key elements of these pathways in the regulation of cellular responses by transmission of signals from receptors to effector proteins. In recent years several studies have reported altered levels and activities of G-protein alpha subunits in depressive patients. A recently identified polymorphism of a G-protein beta3 subunit (C825T) has been shown to be associated with increased signal transduction and ion transport activity. Therefore, we investigated whether this Gbeta3 polymorphism is associated with affective disorders or with the response to antidepressant treatment in 88 depressive patients (10 bipolar disorder, 78 major depression) compared with 68 schizophrenic patients and 111 healthy controls. We found a significantly higher frequency of the T allele in depressive patients than in healthy controls (genotype: chi2 = 9.571, df = 2, p = 0.008; alleles: p = 0.004, OR = 1.87, 95% CI 1.23-2.84; Fisher's exact test, two sided) and schizophrenic patients (genotype: chi2 = 8.037, df = 2, p = 0.018; alleles: p = 0.009, OR = 1.94, 95% CI 1.99-3.14; Fisher's exact test, two sided). We also found a statistical significant association between TT homozygosity and response to antidepressant treatment after four weeks (p = 0.01). The results of this study suggest that the investigated G-protein beta3 subunit seems to be a susceptibility factor for major depression and maybe even for bipolar disorder, but not for schizophrenia. Further, the presence of the T allele could be an indicator for treatment response.

Adult↗
PubMed2000

Increased anti-streptococcal antibodies in patients with Tourette's syndrome.

Infection or postinfectious phenomena have been postulated to play a role in the pathogenesis of children afflicted with the typical symptoms of Tourette's syndrome (TS). We investigated whether an increase of titers of antistreptococcal antibodies can be reproduced in our children with TS, and whether this increase is restricted to children. We examined the titers of two different antistreptococcal antibodies, antistreptolysin (ASL) and anitDNase B, both in children and adults. Titer s of ASO and antiDNase B were measured (1) in 13 children/adolescents suffering from TS and in an aged-matched comparison group;(2) in 23 adult patients, a comparison group of 23 aged-matched controls, and in another group of 17 aged-matched, non-medicated acute schizophrenics. ASO and antiDNase B titers were determined by laser nephelometry using a commercially available kit. Two antistreptococcal cut-off levels were compared (> 250 U/ml and 400 U/ml). As expected, increases ASO titers (>400 IU/ml) were found in a higher portion of children/adolescents with TS compared to controls. Regarding adults, titers >250 U/ml for both antistreptococcal antigens were found in significantly more TS patients than in schizophrenic patients or healthy control subjects. The mean values of ASO and antiDNase titers were significantly higher in both groups of TS patients compared to control children/adolescents, to the comparison groups of healthy adults and to schizophrenics. No difference in antistreptococcal titers was found between schizophrenics and the group of healthy adults. TS patients exhibited higher antistreptococcal titers than age-matched comparison groups of both children/adolescents and adults using different types of calculation. Our findings support the theory that a postinfectious immune mechanism may play a role in the pathogenesis of TS. The mechanism still needs to be elucidated.

Adolescent↗
PubMed2000

Decreased levels of soluble intercellular adhesion molecule-1 (sICAM-1) in unmedicated and medicated schizophrenic patients.

BACKGROUND: The soluble intercellular adhesion molecule-1 (sICAM-1) is a marker for the activation of the cellular immune system. Since an activation of the immune system has been observed in a part of the schizophrenic patients, we measured the serum levels of soluble ICAM-1 (sICAM-1) in schizophrenic patients and correlated them to the patient's psychopathology. METHODS: To monitor a possible effect of antipsychotic therapy, 36 schizophrenic patients were examined twice: first without antipsychotic medication immediately after admission to the hospital and then, after clinical improvement before discharge. The results were compared with those of 36 age- and gender-related healthy individuals. RESULTS: The schizophrenic patients showed significantly decreased serum levels of sICAM-1 at the first examination (248 +/- 95 ng/mL) and at re-examination (266 +/- 95 ng/mL) compared with the comparison group (323 +/- 74 ng/mL). Patients with more pronounced negative symptoms showed higher levels of sICAM-1 at the first examination. CONCLUSIONS: We conclude that reduced sICAM-1 levels in schizophrenia indicate a reduced activity of the cellular immune system in at least a subgroup of schizophrenic patients.

Acute Disease↗
PubMed2000

Dipole localization of P300 and normal aging.

At present, our understanding of how normal aging affects in vivo brain function is rudimentary. Therefore, the aim of the present study was to investigate age effects on auditory P300 topography. A recently developed dipole source model for P300 distinguishes overlapping P300 subcomponents and enhances reliability as well as validity of the measurement. 67 healthy subjects were examined using the P300 dipole model in addition to the scalp data measurement. The results show that P300 subcomponents reflect functionally different processes concerning age changes of P300 activities. Temporo-parietal P300 is smaller in older subjects, whereas frontal P300 is not attenuated. Age affected both P300 subcomponents' latencies. Therefore, the functionally different alteration of P300 subcomponents might be the reason for P300 topography changes with the P300 maximum more frontally in older age.

Acoustic Stimulation↗
PubMed2000

Bronchoscopy in the preoperative staging of oesophageal cancer below the tracheal bifurcation: a prospective study.

Oesophageal cancer located above the level of the tracheal bifurcation is frequently complicated by its spread into the airways and by the simultaneous occurrence of malignant bronchial tumours. Although bronchoscopy is an essential procedure in identifying malignant tumoral invasion of the airways and detection of primary airway tumours in patients with suprabifurcal oesophageal cancer, its role in patients with infrabifurcal oesophageal cancer is not clear. This study aimed to assess the value of fibreoptic bronchoscopy in the preoperative staging of oesophageal cancer located below the level of the tracheal bifurcation. In a prospective protocol, bronchoscopic findings were correlated with the results of other staging procedures, operative results and survival in 51 patients with oesophageal cancer located below the level of the tracheal bifurcation. One unsuspected primary bronchial cancer in a patient with squamous cell oesophageal cancer and one case of lower lobe invasion of an oesophageal adenocarcinoma were found. By excluding from surgery these two patients in whom curative resection was not possible bronchoscopy was the sole decisive staging investigation in 6.5% of potentially operable and 3.9% of all patients. Suspect macroscopic abnormalities were shown in 15.7% of the patients at bronchoscopy. Taking bronchoscopic biopsy as the gold standard the positive predictive value for all macroscopic abnormalities was only 25% (95% confidence interval (CI) 3.2-65.1%). The overall accuracy of bronchoscopy with biopsy and brush and washing cytology in proving or excluding airway invasion in otherwise potentially operable patients was 100% (95% CI 89.4-100%). Bronchoscopy is useful in the preoperative staging of oesophageal carcinoma located below the level of the tracheal bifurcation, particularly if the oesophageal cancer is of the squamous cell type.

Adenocarcinoma↗
PubMed2000

Correlation of micronucleus and apoptosis assays with reproductive cell death can be improved by considering other modes of death.

PURPOSE: To evaluate, using 10 cell lines, the already shown improved correlation between the sum of micronucleated plus apoptotic cells and reproductive cell death. MATERIALS AND METHODS: The cell lines were X-irradiated with doses selected to obtain comparable survival levels. Micronucleated and apoptotic cells as well as abnormal cells (multinucleated and necrotic cells) were counted over several days. Apoptosis was also confirmed by gel electrophoresis. RESULTS: The data confirmed the already shown improved relationship over the solely performed micronucleus or apoptosis assays with reproductive cell death and radiation dose. However, even this approach revealed a saturation after irradiation in certain cell lines. Including other modes of cell death such as mitotic failure or necrosis could eliminate this effect. CONCLUSION: Multiple parameters should be considered when evaluating the use of a predictive assay for ionizing radiation-induced cell killing or biological dosimetry.

Apoptosis↗