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Biomedical subjects

M Reuter

Publications and source records attributed to M Reuter.

At least 37 records · Page 2Linked to original sources

Detection of dysbaric osteonecrosis in military divers using magnetic resonance imaging.

This was a controlled cross-sectional study to investigate the prevalence of dysbaric osteonecrosis (DON) in military divers. MRI examinations of the large joints and adjacent bones were performed in a cross-sectional group of 32 highly experienced military divers and 28 non-divers matched for age and anthropometric data. Additional plain radiographs and follow-up controls were performed in all persons with signs certain or suspicious of DON. In two subject groups (one of divers and one of non-divers), lesions characteristic of DON were detected. From this controlled study, it may be concluded that MRI is a highly sensitive method to detect signs of osteonecrosis. It could be shown that the prevalence of bone lesions characteristic of osteonecrosis in highly experienced military divers is not higher than in non-diving subjects of comparable age. The outcome of this comparably small study group fits to the results of previous extensive studies performed with radiographs. The detected low incidence of DON in this collective may be due to the fact that military divers follow stricter selection criteria, decompression schemes and medical surveillance than commercial divers.

Adult↗

Magnetic resonance imaging and neuropathology findings in the goat nervous system following hyperbaric exposures.

Divers may be at risk of long-term CNS damage from non-symptomatic hyperbaric exposure. We investigated the effect of severe, controlled hyperbaric exposure on a group of healthy goats with similar histories. Thirty goats were exposed to various dive profiles over a period of 5 years, with 17 experiencing decompression sickness (DCS). Brains were scanned using magnetic resonance (MR) imaging techniques. The animals were then culled and grossly examined, with the brain and spinal cord sent for neuropathological examination. No significant correlation was found between age, years diving, DCS or exposure to pressure with MR-detectable lesions in the brain, or with neuropathological lesions in the brain or spinal cord. However, spinal scarring was noted in 3 animals that had suffered from spinal DCS.

Animals↗

Olecranon fractures in adults: factors influencing outcome.

In a retrospective, non-randomized study, we reviewed our experience with the operative treatment of olecranon fractures to find out which factors correlate with subjective complaints and functional outcome. A total of 95 consecutive olecranon fractures were operatively treated in our level I trauma institution between 1 March 1992 and 1 March 2000. Medical records and X-rays of all patients were evaluated. Three patients died, 23 were lost to follow-up. Fifty-eight of 69 available patients (84.0%) were reviewed clinically and/or radiologically after a mean time of 36 months. Fracture type, fracture classification, associated lesions, technical correctness of osteosynthesis, age and comorbidity were analysed. Radiological end result (intraarticular steps, gaps, arthrosis), subjective complaints, mobility of the elbow joint and muscle strength were evaluated. Patients with an unstable elbow (Mayo classification Type III and Schatzker-Schmeling classification Type D) had a higher loss of elbow function than others. There was a correlation between fracture morphology (fractures Type C and Type D in the Schatzker-Schmeling classification) and arthrosis. There also was a correlation between suboptimal osteosynthesis and arthrosis. There was no correlation between suboptimal osteosynthesis, implant loosening and secondary procedures. Patients more often expressed subjective complaints and loss of function in activities of daily life before than after metal removal. Primary elbow instability and fracture morphology are prognostic factors for elbow function and development of arthrosis after operative treatment of olecranon fractures. We, therefore, recommend the classification systems of the Mayo-clinic or of Schatzker-Schmeling. As many patients have complaints related to the implants, we recommend metal removal after fracture healing.

Adult↗

Musculature of an illoricate predatory rotifer Asplanchnopus multiceps as revealed by phalloidin fluorescence and confocal microscopy.

The pattern of muscles in the actively swimming predatory rotifer Asplanchnopus multiceps is revealed by staining with tetramethyl-rhodamine isothiocyanate (TRITC)-labelled phalloidin and confocal scanning laser microscopy (CSLM). The major components of the musculature are: prominent semicircular muscles of the corona; paired lateral, dorsal and ventral retractors in the trunk; a network of six seemingly complete circular muscles and anastomosing longitudinal muscles in the trunk; two short foot retractors, originating from a transverse muscle in the lower third of the trunk. The sphincter of the corona marks the boundary between the head and the trunk. The muscular patterns in rotifers with different lifestyles differ clearly, therefore, the muscular patterns seem to be determined by the mode of locomotion and feeding behaviour.

Animals↗

Personality and emotion: test of Gray's personality theory by means of an fMRI study.

Although it is known that there are fundamental personality differences in the behavioral responses to emotional stimuli, traits have scarcely been investigated in this context by means of functional imaging studies. To maximize the variance with respect to personality, the authors tested 12 control subjects and 12 subjects who had sadomasochistic experiences with respect to the relationship between J. A. Gray's (1970) personality dimensions, the behavioral approach system (BAS) and the behavioral inhibition system (BIS), and brain activity in regions of interest. The BIS was associated with activity in numerous brain areas in response to fear, disgust, and erotic visual stimuli, whereas few associations could he detected between the BAS and brain activity in response to disgust and erotic stimuli.

Adult↗

[Inflammatory aortic arch syndrome: contrast-enhanced, three-dimensional MR angiography in stenotic lesions].

PURPOSE: To determine the value of contrast-enhanced, three-dimensional MR angiography for the evaluation of stenotic and occlusive vascular lesions in inflammatory aortic arch syndrome. MATERIALS AND METHODS: 14 patients with inflammatory aortic arch syndrome (giant cell arteritis: n = 8, Takayasu arteritis: n = 4, ankylosing spondylitis: n = 1 sarcoidosis: n = 1) underwent MR angiography of the aortic arch and the supra-aortic vessels (n = 15, 2 patients were examined twice) and of the abdominal aorta (n = 2). MRA was performed using a 3D-FLASH sequence (TR/TE 4.6/1.8 ms, flip angle 30 (3)) on a 1.5T system. MRA imaging was compared with the findings of DSA, which served as gold standard. RESULTS: In a total of 467 examined vascular territories, DSA revealed 50 stenoses and 35 occlusions. All lesions were detected by MRA. In 23 segments, the degree of stenosis was overestimated by MRA. Sensitivity and specificity of MRA were 100 % and 94.3 %, positive and negative predictive values were 73.6 and 100 %, and the accuracy was 95.1 %. CONCLUSIONS: Despite a tendency to overestimate stenoses, contrast-enhanced three-dimensional MR angiography is a valid, non-invasive technique in the assessment of inflammatory aortic arch syndrome.

Adult↗

[The role of magnetic resonance imaging in the preoperative evaluation of the peripancreatic vasculature in pancreas carcinoma].

PURPOSE: To evaluate the accuracy of magnetic resonance angiography (MRA) to predict vascular involvement in pancreas carcinoma. MATERIALS AND METHODS: This prospective trial included 42 patients with suspected pancreas carcinoma. All patients underwent MRA, different tomographic sequences (MRI) and surgery. Peripancreatic vessels were analyzed for vascular involvement, with the tumor infiltration graded on a scale of 0 to 4 (grade 0 - 4). The imaging findings were correlated with surgery and histopathology. RESULTS: The sensitivity of MRA to predict vascular involvement was 61 % (19 of 31 evaluated vessels) and the specificity 97 % (148 of 153). Sensitivity and specificity for axial MRI were both 94 % (29 of 31 and 144 of 153 evaluated vessels). The difference in the sensitivities of MRA and MRI was statistically significant (p < 0.01). Vascular involvement was correctly graded in 58 % (18 of 31) by MRA and in 74 % (23 of 31) by MRI. CONCLUSION: MRA alone is not sufficient to diagnose vascular involvement in pancreas carcinoma, but provides an adequate overview of the vascular anatomy. A combined protocol of MRA and MRI is needed for an acceptable evaluation of the peripancreatic vessels.

Aged↗

Functional results after operative treatment of olecranon fractures.

In a retrospective, nonrandomized study, we reviewed our experience with the operative treatment of olecranon fractures to find out which factors correlate with subjective complaints and functional outcome. A total of 95 consecutive olecranon fractures were operatively treated in our level I trauma institution between March 1, 1992 and March 1, 2000. Medical charts and radiographs of all patients were evaluated. Three patients died, 23 were lost to follow-up. Fifty-eight of 69 available patients (84.0%) were reviewed clinically and/or radiologically after a mean time interval of 36 months. Fracture type, fracture classification, associated lesions, technical correctness of osteosynthesis, age and comorbidity were analysed. Radiological end result (intraarticular step-offs, gaps, arthrosis), subjective complaints, mobility of the elbow joint and muscle strength were evaluated. Patients with an unstable elbow (Mayo classification type III and Schatzker-Schmeling classification type D) had a higher loss of elbow function than others. There was a correlation between fracture morphology (fractures type C and D in the Schatzker-Schmeling classification) and arthrosis. There also was a correlation between suboptimal osteosynthesis and arthrosis. There was no correlation between suboptimal osteosynthesis, implant loosening and secondary procedures. Patients more often expressed subjective complaints and loss of function in activities of daily life before than after hardware removal. Primary elbow instability and fracture morphology are prognostic factors for elbow function and development of arthrosis after operative treatment of olecranon fractures. We therefore recommend the classification systems of the Mayo-clinic or of Schatzker-Schmeling. As many patients have complaints related to the implants, we recommend hardware removal after fracture healing.

Adult↗

Incidence of abnormal cerebral findings in the MRI of clinically healthy divers: role of a patent foramen ovale.

BACKGROUND: To investigate incidence and number of abnormal cerebral hyperintensities (ACFs) in Magnet Resonance Imaging (MRI) and its relation to a patent foramen ovale (PFO) in divers with no history of decompression illness. METHODS: Cohort study on 50 divers (21-5500 dives). MAIN OUTCOME MEASURES: Incidence and number of ACFs visualized by cranial MRI and presence and size of a PFO as documented by echocardiography and transcranial Doppler ultrasound (TCD) with echocontrast. RESULTS: A total of 137 ACFs was found in the 50 subjects, with a significant correlation between the number of dives and number of ACFs (r = 0.28; p < 0.05); but after correction for age, the remaining correlation (r = 0.15) did not reach significance. In 18 divers, a PFO was present by either the application of echocardiography or TCD; in 12 divers, the PFO was of high hemodynamic relevance. Ten of 18 divers with a PFO had at least one ACF, while in the remaining 32 divers, only 14 had at least one ACF (56% versus 44%, p = NS). Seven of 14 divers (50%) with 4 ACFs had a PFO, compared to 11 of 36 (31%) with less than 4 ACFs (p = NS). CONCLUSION: In this cohort of healthy divers, in contrast to an earlier report, no significant association was found between PFO presence and incidence or number of ACFs.

Adult↗

Correlation between HRCT findings, pulmonary function tests and bronchoalveolar lavage cytology in interstitial lung disease associated with rheumatoid arthritis.

A prospective study correlating high-resolution computed tomography (HRCT), lung function tests (PFT) and bronchoalveolar lavage (BAL) cytology in patients with interstitial lung disease (ILD) associated with rheumatoid arthritis (RA). Fifty-three RA patients with suspected ILD (19 men, 34 women) underwent 71 HRCT (14 of 53 with sequential HRCT, mean follow-up 24.3 months). The HRCT evaluation by two observers on consensus included a semi-quantitative characterisation of lesion pattern and profusion on representative anatomical levels. Fifty-two HRCT were followed by PFT and BAL. Agreement or discordance of HRCT-, PFT- and BAL findings were analysed with Pearson's correlation, kappa score and McNemar's test. Tobacco-fume exposure was estimated in pack years. Smoking/non-smoking groups were compared with Student's t test. In 49 of 53 patients, HRCT was suggestive of ILD associated with RA (66 of 71 HRCT). Reticular lesions were found in 40 of 53 patients, in 15 of 40 presenting as mixed pattern with ground-glass opacities (GGO). Pure reticular patterns predominated in patients with long duration of ILD (p>0.01). Pure GGO were not observed. Lesion profusion was highly variable and correlated moderately negative with diffusion capacity (mean 88.2% (SD +/- 20.9%); r=-0.54; p<0.001) and very weak with vital capacity and FEV1 (mean values 92.2% (SD +/- 18.3%); r=-0.27; p<0.05 and 89.8% (SD +/- 17.5%); r=-0.31; p<0.01). In patients with GGO, BAL differentials tended towards neutrophilia (kappa=0.39; p=0.04; McNemar test p>0.2), but not towards lymphocytosis (kappa=0.10; p=0.23; McNemar test p>0.2). Differences in smoking history were not significant (p>0.1). The HRCT appears most appropriate for the detection and follow-up of ILD associated with RA. The PFT and BAL correlate only partially with lesion profusion or grading on HRCT, but they contribute valuable information about dynamic lung function and differential diagnoses (pneumonia, medication side effects).

Aged↗

Significance of the fragmentation region in ultrarelativistic heavy-ion collisions.

We present measurements of the pseudorapidity distribution of primary charged particles produced in Au+Au collisions at three energies, sqrt[s(NN)]=19.6, 130, and 200 GeV, for a range of collision centrali-ties. The distribution narrows for more central collisions and excess particles are produced at high pseudorapidity in peripheral collisions. For a given centrality, however, the distributions are found to scale with energy according to the "limiting fragmentation" hypothesis. The universal fragmentation region described by this scaling grows in pseudorapidity with increasing collision energy, extending well away from the beam rapidity and covering more than half of the pseudorapidity range over which particles are produced. This approach to a universal limiting curve appears to be a dominant feature of the pseudorapidity distribution and therefore of the total particle production in these collisions.

Journal Article↗

Percutaneous management of occlusive arterial disease associated with vasculitis: a single center experience.

The purpose of this study was to evaluate the safety and effectiveness of percutaneous transluminal angioplasty for occlusive arterial disease associated with vasculitis. Eleven patients (10 women, 1 man; ages 35-82 years) with the diagnosis of vasculitis of the large vessels underwent interventional treatment during intraarterial angiography. The causes included giant cell arteritis (n = 8) and Takayasu arteritis (n = 3). Thirty-three occlusive lesions (including brachiocephalic and renal arteries, and arteries of upper and lower extremities) were treated with balloon angioplasty and/or stent placement. Follow-up included clinical examination, angiography, and color duplex ultrasound. Technical success was 100% (25/25) for stenoses and 50% (4/8) for occlusive lesions, representing all lesions combined from different anatomic locations. Dissection (n = 3) and arterial rupture with retroperitoneal hematoma (n = 1) was found in three patients. During follow-up (mean 12 months), restenoses (n = 8) and re-restenoses (n = 1) occurred in 8 vascular areas. Three of these lesions were treated with repeated PTA (n = 4). The cumulative primary clinical success rate was 67.6%, cumulative secondary success rate 74.4%, and cumulative tertiary success rate 75.9%. Interventional therapy in systemic vasculitis provides promising results in technical success rates and followup. Angioplasty may result in arterial injury, but the rate of complications is low.

Adult↗

Cortisol as an indicator of dopaminergic effects on nicotine craving.

There is evidence that glucocorticoids mediate the activity of mesencephalic dopaminergic neurons which play an important role in drug-seeking behaviour and that the absence or presence of glucocorticoids determines the intensity of drug self-administration. Moreover, some experiments indicate that corticoids are increased after substance induced dopaminergic stimulation. These findings could imply (a) that differences in basal glucocorticoid levels are associated with differences in craving or (b) that dopamine (DA) induced corticoid release is an indicator of the sensitivity of the dopaminergic system. Therefore, in a sample of 36 male smokers whose DA system was challenged by a DA agonist (lisuride=LIS) and a DA antagonist (fluphenazine=FLU) in a balanced placebo controlled double-blind crossover design, it was investigated if (a) basal cortisol differences and (b) drug induced cortisol responses are related to the amount of nicotine craving after 3.5 h of deprivation from smoking. There were no differences in craving between subjects with high and low basal cortisol levels irrespective of the pharmacological treatment. However, the size of the cortisol change after the DA challenge and deprivation emerged as a good predictor for the amount of craving in that drug condition in which the cortisol response was most pronounced. Findings were interpreted as evidence for the role of cortisol as an indicator of DA sensitivity.

Adult↗

Rule learning in a serial reaction time task: an fMRI study on patients with early Parkinson's disease.

In the present study, we investigated implicit rule learning in patients with Parkinson's disease (PD) and healthy participants. Functional magnetic resonance imaging (fMRI) and a variant of the serial reaction time task were employed to examine the performance of previously learned regular sequences. Participants responded to successively appearing visual stimuli by pressing spatially corresponding keys. Unbeknownst to them, a cycling 12-item sequence was presented. In order to measure rule learning independently from initial visuomotor learning, participants were trained with the sequence prior to scanning. In the fMRI session, alternating blocks of regular and random stimuli were performed. Imaging revealed activations in the frontomedian and posterior cingulate cortex during performance of sequence blocks as opposed to random blocks. The magnitude of activations in these two areas was correlated with the behavioral index for rule learning. As has been reported earlier, the frontomedian cortex may be involved in the prediction of future stimuli and anticipation of corresponding actions, whereas the posterior cingulate activation may rather be related to memory retrieval. Additional activations of the right putamen and the inferior frontal sulcus were not related to behavioral performance. In patients with early PD, the behavioral data showed reduced training effects during pretraining, but intact rule learning during the fMRI session. Imaging revealed highly similar frontomedian and posterior cingulate activations in patients and controls, in the absence of significant striatal and inferior frontal activations in patients. Our findings support the view that in early PD, with the lateral striatofrontal dopaminergic projections being affected, medial dopaminergic projections involved in the application of previously learned rules may still be spared.

Aged↗

[Radiology of the primary systemic vasculitides].

Determination of disease extension and disease activity are in the foreground of diagnostic imaging in vasculitides. There are several radiologic modalities available each having specific indications. Magnetic resonance imaging (MRI) readily depicts granulomas and mucosal inflammations in the paranasal sinuses, nasal cavity and orbits. Computed tomography detects osseous lesions of the skull. Due to its superb sensitivity MRI is an established screening modality for CNS vasculitides, although there are limitations with regard to specificity. In spite of its limited accuracy in most institutions angiography is still required for radiological confirmation of CNS vasculitis. Perfusion and diffusion MR-imaging may combine the advantages of "conventional" MRI and angiography. By now the method is not fully validated for vasculitides, however. Vascular disease in Takayasu's arteritis and in giant cell arteritis involving predominantly large and medium sized vessels is readily diagnosed by non invasive magnetic resonance angiography. Percutaneous transluminal angioplasty has proven to be an effective and save therapeutic modality for the cure of vascular stenoses and occlusions. Plain film radiography in two planes is the established modality for pulmonary imaging. In pulmonary vasculitides a more thorough analysis of lung disease is provided by high resolution computed tomography. Diagnostic imaging does substantially assist in the interdisciplinary management of patients suffering from vasculitides.

Adolescent↗

Pseudorapidity and centrality dependence of the collective flow of charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV.

This paper describes the measurement of collective flow for charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0<eta<5.3) for the first time at this energy. The result, averaged over momenta and particle species, is observed to reach 7% for peripheral collisions at midrapidity, falling off with centrality and increasing |eta|. These results call into question the common assumption of longitudinal boost invariance over a large region of rapidity in RHIC collisions.

Journal Article↗