Biomedical subjects

B Rieger

Publications and source records attributed to B Rieger.

11 recordsLinked to original sources

PubMed2005

[Is the Canadian CT head rule for minor head injury applicable for patients in Germany?].

PURPOSE: To evaluate the applicability of the Canadian CT Head Rule (CCHR) on head trauma patients in a German university hospital. METHODS: 122 patients (m = 74; f = 48; 40 +/- 19 years) were examined with cranial CT due to minor head trauma. The need for cranial CT according to the CCHR was evaluated retrospectively. RESULTS: With a sensitivity of 98.9 % and a specificity of 46.6 % all patients with the need for neurosurgical intervention were detected by applying the major criteria of the CCHR. Also, every patient with severe brain injury was detected by the extended criteria with a sensitivity of 99.6 % and a specificity of 34.1 %. This would have led to a reduction in the rate of cranial CT examinations by 45.1 % for the major and 22.1 % for the extended criteria. No patient with severe brain injury would have been missed by application of the criteria. CONCLUSION: The Canadian CT Head Rule for patients with minor head trauma is applicable with a very high sensitivity and the potential of significantly reducing the rate of cranial CT examinations in these patients.

Accidental Falls↗

PubMed2004

Alignment of the cell nucleus from labeled proteins only for 4D in vivo imaging.

Studies of protein dynamics by 4D (3D + time) confocal microscopy in vivo are hampered by global cell motion. The time between the acquisitions of the 3D images is in the order of minutes. Therefore, it is not to be expected that the cell as a whole remains fixed in the water basin on the stage. This superimposes a motion on the protein dynamics that has to be removed. We present a robust registration technique to align the cell images that does not require the a priori establishment of point-to-point correspondences. Instead, it uses the distribution of the labeled proteins. After correction for the translation, the 3D rotation of the cell is estimated. A robust intrinsic body coordinate system is constructed via the inertia tensor from the intensity distribution. By combining basis transformation to this intrinsic coordinate system, we can calculated the rotation matrix in a conceptual and computational straightforward manner. We have evaluated the performance of this approach in three experiments with human osteaosarcoma cells (U-2 OS), where the nuclear proteins Histon H4 and PML were visualized. The PML is concentrated in several dozen nuclear spots. Expression of Histon H4 results in a total nuclear staining. The registration results for both channels computed independently are very similar. Practically, this means that only the labeled material needs to be observed and still registration of the cell as a whole can be achieved.

Algorithms↗

PubMed2004

Diffusion of microspheres in sealed and open microarrays.

In several experiments, we study the diffusion of microspheres with different radii in microarrays filled with a variety of aqueous solutions of ethylene glycol. We study diffusion in open and closed (sealed) microarrays. In sealed nanoliter wells, the tracers show pure diffusion, whereas in open reactors, a radial outward-directed evaporation-induced liquid flow is superimposed onto the diffusion. In general, one of the following quantities can be calculated if the others are known: the temperature, the viscosity of the medium, the radius of the microbeads, or the diffusion constant. The estimated diffusion constants in closed microarrays are in good agreement with theoretical predictions based on the Brownian motion. We monitor the motion of the microbeads under a microscope and extract their paths in time from the digital recordings. Ambiguous paths due to the crossing of two trajectories can be detected. We show that low microsphere concentrations or high viscosities do not hamper a robust estimation of the diffusion parameters.

Algorithms↗

PubMed2003

Ring formation in nanoliter cups: quantitative measurements of flow in micromachined wells.

Drying of DNA spots on microarrays and spilled coffee yields ringlike stains, because the outward flow transports dissolved particles to the border. Contact line pinning and diffusion limited evaporation of a liquid sample are the two necessary conditions to induce an outward directed liquid flow during evaporation. In this paper we present quantitative measurements of this flow field visualized by microspheres which are injected into a liquid sample in circular wells with a radius of 100-150 micro m and a depth of 6 micro m. The motion, including Brownian motion, of these microspheres with a radius of 0.25 micro m is recorded using digital fluorescence microscopy. Our analysis, using optic flow, does not require object identification, nor tracking of the individual objects. The spatiotemporal measurement space is sparsely filled at only those space/time positions where a microsphere is present. A confidence measure is computed indicating the presence of microspheres in this measurement space. The circular well shape allows us to transform the sparse measurement space into a denser, averaged radial velocity field. In this transformation we "interpolate" the radial velocity between values with a high confidence, which results in quantitative measurements of this outward flow field during the complete time interval of the evaporation process and at all radial positions in the circular wells. This allows for a quantitative validation of the elegant theory of ring formation.

Journal Article↗

PubMed2003

Plasma cell granuloma involving the brain and the lung.

BACKGROUND: Symptomatic plasma cell granulomas (PCG) of the central nervous system (CNS) are a rare entity, especially in association with an extracranial manifestation. CLINICAL PRESENTATION: A 13 years old boy was operated on for a symptomatic plasma cell granuloma of the lower lobe of the left lung. Four years later, he suffered his first generalized seizure. CT and MRI scans revealed a small hyperdense lesion, which was located in the right frontal lobe, adjacent to the motor strip. Intervention. Stereotactic guided surgery was performed. A plasma cell granuloma was found, which histopathologically resembled the intrapulmonary lesion, which had been removed four years ago. CONCLUSION: Histological findings, differential diagnosis and specific treatment are reviewed and discussed. Patients with PCG should be radiologically staged. Long term prognosis of PCG is good in cases surgically resectable. Nevertheless, patients require lifelong follow up.

Adolescent↗

PubMed2003

First night effect in children and adolescents undergoing polysomnography for sleep-disordered breathing.

OBJECTIVE: To establish whether there is a first night effect (FNE) in children and adolescents with suspected obstructive sleep apnoea undergoing polysomnography (PSG) and whether this affects sleep and breathing, furthermore, to determine the extent to which age may influence the sleep and cardiorespiratory parameters. METHODS: One hundred and thirty-one children and adolescents (age classes-A: 2-6 years n=37; B: 7-12 years n=60; C: 13-17 years n=34) underwent PSG on 2 consecutive nights (I and II) under identical conditions for suspected sleep-related respiratory disorders. One hundred and five patients including 3 patients with obstructive sleep apnoea syndrome (OSAS) treated by adenotonsillectomy and 18 OSAS patients receiving nCPAP-therapy had no PSG-abnormalities (Group 1-A: n=28; B: n=53; C: n=24). A further 26 patients (Group 2) had clinically and polysomnographically confirmed untreated OSAS (A: n=9; B: n=12; C: n=5). RESULTS: There were no statistically significant differences between children with no PSG-abnormalities (Group 1) and those with OSAS (Group 2) in terms of sleep parameters (arousal indices excluded), oxygen saturation (SaO(2)) and heart rate (HR), and these parameters have, therefore, been pooled for the entire group (n=131) in the 3 age classes A, B and C. In the second and third age classes, sleep efficiency on the first night was reduced. In all age classes, there was significantly more wakefulness during the first night. In the second and third age ranges, the proportion of NREM 1 in the first night was significantly higher, with a correspondingly reduced proportion of NREM 4 in the third age group. In all age classes, REM sleep was significantly less during the first night, but REM latency was comparable on both nights. On the first night, the mean HR was higher. There were significant differences in apnoea/hypopnoea-index (AHI), electroencephalogram (EEG)-arousal-index (AI) and motoric arousal index (jerk index, JI) between Groups 1 and 2. In neither group, were there any significant differences in AHI, mean SaO(2) or number of EEG-arousals between nights 1 and 2. Only in the age class A, in Group 2 (n=9) was the number of motoric arousals significantly higher on the first night. Comparison of the age classes A, B, and C revealed that most polysomnographic parameters were age-dependent. Increasing age was found to correlate with a higher proportion of NREM 1, especially on the first night. Also, there was an age-dependent increase in NREM 2 on both nights, a decrease in NREM 3 on the first night, and a decrease in NREM 4 on both nights. In older children, we also found a lower proportion of REM sleep on the first night and a lower HR on both nights. In Group 1, we found a lowered AHI, AI and JI (for JI significant only on the first night) in older patients. No such age dependence of AHI, AI and JI was seen in OSAS patients (Group 2). CONCLUSIONS: In children and adolescents, there is an FNE comparable with that described in adults. In OSAS children and also in children with no PSG-abnormalities, there is night-to-night-variability in sleep parameters, but not in respiratory parameters. An adaptation night is, therefore, necessary when sleep architecture is to be studied, but not when only the nocturnal respiratory pattern is investigated. Sleep parameters, HR and arousal indices are all age-dependent.

Adolescent↗

PubMed1997

[Adeno-tonsillar hyperplasia and obstructive sleep related respiratory disorders].

The most common cause of obstructive apnoeas in children is adenotonsillar hyperplasia. Possibilities of therapy are surgical intervention (adeniodectomy, tonsillectomy) or nasal CPAP. The decision on the most appropriate therapy must be individual. 26 children aged 2-5 years were investigated polysomnographically before therapy, after operation or with nCPAP-therapy. Polygraphy is a helpful aid in making up one's mind in favour of one of the possibilities of therapy, but also for controlling the therapeutic effect.

Adenoidectomy↗

PubMed1996

Interactive effect of combined exposure to glycol ethers and alcohols on toxicodynamic and toxicokinetic parameters.

Ethylene glycol monomethyl ether (EGME) exhibits testicular toxicity and ethylene glycol monobutyl ether (EGBE) is a solvent with haemolytic effects in rats. The study of the interaction of two glycol ethers (EGME and EGBE) and three alcohols (ethanol, n-propanol and n-butanol, 10 or 30 mmol/kg), orally co-administered in male rats, was carried out from a toxicodynamic and toxicokinetic point of view. Administered alone, EGME (10 mmol/kg) caused a 30- and 5-fold increase in the urinary creatine/creatinine ratio at 24 and 48 h, respectively, and 24 h urinary excretion of methoxyacetic acid was of 0.71 +/- 0.042 mmol 24 h (mean +/- SE). The simultaneous administration of one of the three alcohols at either of the doses mentioned above did not significantly modify the urinary creatine/creatinine ration (24 and 48 h), or the 24 h urinary excretion of methoxyacetic acid. Administered alone, EGBE (5 mmol/kg) caused an average decrease of 26% in the number of circulating red blood cells and a strong (250 times) increase in the level of plasma haemoglobin 4 h after treatment. Urinary excretion of butoxyacetic acid in rats treated with EGBE (1 mmol/kg) was 0.083 +/- 0.0039 mmol/24 h (mean +/- SE). The simultaneous injection of 30 mmol/kg alcohol (ethanol, n-propanol or n-butanol) almost totally inhibits the haemolytic effect of EGBE, and decreases the urinary excretion of butoxyacetic acid by 43-31%. A strong dose of alcohol (30 mmol/kg) decreases the haemolytic effect due to EGBE, and reduces the urinary excretion of butoxyacetic acid. In contrast, the coadministration of alcohol did not modify the testicular toxicity of EGME, or the 24 h urinary excretion of methoxyacetic acid. It is possible that competitive inhibition of alcohol dehydrogenase by alcohols results in the diversion of EGBE metabolism.

Alcohols↗

PubMed1996

[nCPAP/nBIPAP therapy in sleep-related obstructive respiratory disorders in childhood].

nCPAP/nBIPAP-therapy is a possibility of treatment of sleep related disturbances also in childhood. We will demonstrate the therapeutic effect of therapy in 13 patients in the age range 3 to 14 years on behaviour, school performance, number of infections in the upper airways as well as on polygraphic parameters, i.e., sleep structure, number of apneas, oxygen saturation and mean heart rate.

Child↗

PubMed1994

Occupational exposure to organic solvents during paint stripping and painting operations in the aeronautical industry.

The exposure of workers to methylene chloride and phenol in an aeronautical workshop was measured during stripping of paint from a Boeing B 747. Methylene chloride exposure was measured during two work days by personal air sampling, while area sampling was used for phenol. During paint stripping operations, methylene chloride air concentrations ranged from 299.2 mg/m3 (83.1 ppm) to 1888.9 mg/m3 (524.7 ppm). The exposures to methylene chloride calculated for an 8-h work day ranged from 86 mg/m3 (23.9 ppm) to 1239.5 mg/m3 (344.3 ppm). In another aeronautical workshop, exposure to organic solvents, especially ethylene glycol monoethylether acetate (EGEEA), was controlled during the painting of an Airbus A 320. The external exposure to solvents and EGEEA was measured by means of individual air sampling. The estimation of internal exposure to EGEEA was made by measuring its urinary metabolite, ethoxyacetic acid (EAA). Both measurements were made during the course of 3 days. The biological samples were taken pre- and post-shift. During painting operations, methyl ethyl ketone, ethyl acetate, n-butyl alcohol, methyl isobutyl ketone, toluene, n-butyl acetate, ethylbenzene, xylenes and EGEEA were detected in working atmospheres. For these solvents, air concentrations ranged from 0.1 ppm to 69.1 ppm. EGEEA concentrations ranged from 29.2 mg/m3 (5.4 ppm) to 150.1 mg/m3 (27.8 ppm). For biological samples, the average concentrations of EAA were 108.4 mg/g creatinine in pre-shift and 139.4 mg/g creatinine in post-shift samples. Despite the fact that workers wore protective respiratory equipment during paint spraying operations, EEA urinary concentrations are high and suggest that percutaneous uptake is the main route of exposure for EGEEA.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗

PubMed1982

Antibody-independent complement activation by myelin via the classical complement pathway.

Murine or rabbit whole brain homogenates were shown to activate human complement via the classical pathway by an antibody-independent reaction. This activity required Ca++ ions. Anticomplementary activity in fractionated murine brain was found to reside in the myelin fraction and in purified myelin. It was absent, however, both from highly purified myelin basic protein (MBP) and from the MBP-free residue. Because purified MBP is a monomer and this protein exists in brain tissue largely as a dimer, the ability of the cross-linked form of MBP to activate complement was investigated. MBP, dimerized with difluorodinitrobenzene, was highly anticomplementary. The murine brain, inactive when taken from the newborn mouse, was shown to first acquire the capacity to activate complement at 7 d after birth. This finding is consistent with the report that the synthesis of myelin protein has been shown to be initiated in murine brain 8 d after birth. Complement activation by MBP could play an important role in the pathological changes observed in neurological disorders.

Animals↗