Biomedical subjects

M Biedermann

Publications and source records attributed to M Biedermann.

At least 19 recordsLinked to original sources

PubMed2006

[A complication during kyphoplasty. Cement penetration through the azygos vein into the superior vena cava].

A 59-year-old woman had a nontraumatic osteoporotic fracture of the seventh thoracic vertebral body. Despite correct operative technique, in the course of kyphoplasty cement was dislocated through the segment vein into the azygos vein and from there into the superior vena cava. The patient was free of cardiopulmonary symptoms throughout. Oral anticoagulation was administered for 3 months to prevent thromboembolism, and regular clinical and echocardiographic follow-up examinations were also performed during this period.

Bone Cements↗

PubMed2004

Relative hopane content confirming the mineral origin of hydrocarbons contaminating foods and human milk.

Hopanes, triterpenoid hydrocarbons formed under geological conditions, were analysed to confirm the mineral origin of the unresolved complex mixtures of hydrocarbons observed in the gas chromatography with flame ionization detection chromatograms of human milk and certain foodstuffs. The 'relative hopane content' (RHC) is introduced, i.e. it is the area ratio of the sum of the hopanes and the paraffins in the same segment of the chromatogram. The RHC in various mineral oil products (motor oils, hydraulic oils, lubricating oils, Vaseline) was 3.4%, with a relative standard deviation of 19%. The RHC determined in samples of vegetable oils, mussels and clams as well as of human milk containing an unresolved complex mixture of hydrocarbons was in the same range, confirming that these samples were contaminated by mineral oil material.

Animals↗

PubMed2002

Obstacle avoidance during human walking: transfer of motor skill from one leg to the other.

The aim of this study was to evaluate whether a newly acquired locomotor skill can be transferred to the mirror condition. Subjects were trained to step over an obstacle on a treadmill, the appearance of which was signalled by an acoustic stimulus, while visual information was prevented. Feedback information about foot clearance was provided by acoustic signals. During two successive runs (each consisting of 100 steps over the obstacle) the same leg was leading (i.e. the leg crossing the obstacle first). In the following third run, the leading and trailing legs were changed. During each of the three successive runs the adaptational changes were analysed by recording leg muscle electromyographic (EMG) activity, joint angle trajectories and foot clearance over the obstacle. The training effect gained between the first and second runs and the transfer to the mirror condition (third run) were evaluated. Adaptational changes of all measures, except ankle joint trajectory, could to a significant extent be transferred to the mirror condition. No side-specific differences in the amount of transfer were found, neither from the right to the left side, nor vice versa. These observations are at variance with adaptational changes observed during split-belt walking or one-legged hopping on a treadmill, where no transfer to the mirror condition occurred. It is assumed that this might be due to the specific requirements of the tasks and the leg muscles involved. While in the split-belt and hopping experiments leg extensor muscles are mainly involved, leg flexors predominate in the performance of the present task. It is hypothesised that the learning effects observed in the present experiments are mediated at a higher level (e.g. brainstem) of locomotor control.

Adaptation, Physiological↗

PubMed2001

Contamination of animal feed and food from animal origin with mineral oil hydrocarbons.

Oils and fats used for the production of animal feed can become contaminated with mineral oil material originating from gas oils (C18-C35) or synthetic oils (poly-alpha olefins, C25 to beyond C45). An important cause is assumed to be the discharge of waste oils, such as motor oil and hydraulic oils. Mineral oil material was analysed by on-line LC-GC-FID directly in the fat or in a raw extract from animal feed or foodstuffs. In Switzerland in summer/autumn 1999 concentrations in oils and fats for feed production were often found to be between 100 and 1000 mg/kg. In the feeds, the average concentration was around 100 mg/kg with values ranging up to a maximum of 1000 mg/kg; few samples were free of contamination. In animal body fat, the average concentration determined in summer 1999 was 25 mg/kg, with a maximum of 150 mg/kg, although in samples from December 1999, contamination was substantially lower. In the fat phase of eggs, the average concentration was 30 mg/kg, with a maximum of 80 mg/kg. Paraffin oil is used for feed production, which may account for part of the contamination problem (e.g. eggs).

Animal Feed↗

PubMed2001

Method for determining novolac glycidyl ether (NOGE) and its chlorohydrins in oily canned foods.

In order to be analysed, NOGE components with epoxy groups must be separated from polar food material to prevent losses through uncontrolled reactions. Samples are homogenized minimally and extracted into a phase of minimized polarity. The NOGE components are then separated from the oil by extraction into acetonitrile and analysed by RPLC with fluorescence detection. Hydrolysis of the epoxy, and chlorohydroxy functions to diols may help the analysis. Application and limitations of the method are illustrated by examples. Detection limits vary widely, depending on interfering food components, but legal limits below 1 mg/kg can hardly be reliably enforced.

Animals↗

PubMed2000

Video-taped sample evaporation in hot chambers simulating gas chromatography split/splitless injectors. I. Thermospray injection.

The processes in devices imitating vaporising injectors were visualised and video-taped using perylene as a fluorescent marker for non-evaporated samples. The observations in the context of thermospray injection are summarised. Partial evaporation inside the needle turns the solvent into a propellant which nebulises the sample liquid at the needle exit. Evaporation in the vaporising chamber occurs from fine droplets suspended in the gas phase. Empty injector liners are best suited; packings with glass wool or obstacles in the liner, like the cup, have no significant effect on the process observed. Non-evaporated (matrix) material forms aerosol particles which may enter the column together with the vapours, but most of them are transferred to the liner wall. Since solute material may be carried along, this is a possible source of matrix effects.

Chromatography, Gas↗

PubMed2000

Video-taped sample evaporation in hot chambers simulating gas chromatography split and splitless injectors. II. Injection with band formation.

The processes in devices imitating a vaporising injector were video-taped using perylene as a fluorescent marker for non-evaporated sample. Processes are summarised which are observed after the sample liquid passed through a cool needle and left as a band of liquid moving at high velocity (as typical for injection by fast autosamplers). This liquid is shot past the column entrance unless stopped either by a packing, e.g., wool or by suitable obstacles. Packings of low thermal mass are locally cooled to the solvent boiling point and suck in the liquid. Stopping the liquid by obstacles is more difficult because solvent vapours prevent contact of the liquid with the hot surfaces, and was reliably achieved only by the laminar liner. For the same reason, transfer onto the liner wall only occurs for higher boiling liquids.

Chromatography, Gas↗

PubMed2000

Introduction of large volumes of water-containing samples into a gas chromatograph. Improved retention of volatile solutes through the swing system.

The swing system is designed for introducing large volumes of water-containing samples into a gas chromatograph. Sample evaporation and solvent-solute separation are performed in separate compartments. This widens the application range to compounds of higher volatility. Sample evaporation takes place in a hot chamber packed with Carbofrit. Solvent-solute separation is performed in a cascade of increasing powers of retention. While high boiling solutes are retained in an oven-thermostatted retaining precolumn, the more volatile components are retained by a packed bed of sorbents of increasing powers of retention situated in a programmed temperature vaporiser. For elution, the gas flow is reversed and the solutes are discharged from the heated packed bed through the retaining precolumn into the separation column.

Chromatography, Gas↗

PubMed1998

Food contamination from epoxy resins and organosols used as can coatings: analysis by gradient NPLC.

Normal phase LC with gradient elution enabled the analysis of a broadened range of oligomers of BADGE (Bisphenol-A diglycidyl ether) and Novolak compounds in canned foods, such as sea foods in oil, meat products and soups. A major component released from Bisphenol-A resins was identified as the cyclo-(Bisphenol-A monoglycidyl ether) dimer and was commonly present in foods at concentrations of around 1 mg/kg. For the epoxy Novolaks, concentrations of the three- to six-ring compounds often far exceeded those of BFDGE (Bisphenol-F diglycidyl ether) and reached 20 mg/kg in foods. A two-step acylation is proposed for the detection of epoxy components.

Benzhydryl Compounds↗

PubMed1998

Clinical results using the trochanter stabilizing plate (TSP): the modular extension of the dynamic hip screw (DHS) for internal fixation of selected unstable intertrochanteric fractures.

OBJECTIVE: To evaluate whether the implantation of the modular trochanter stabilizing plate (TSP) in addition to the dynamic hip screw (DHS) prevents excessive telescoping and limb shortening in four-part and selected three-part trochanteric fractures. DESIGN: Prospective clinical study. SETTING: The study was conducted at the trauma unit of the Surgical Department of the University of Basel, Switzerland. PATIENTS: Forty-six consecutive patients with unstable intertrochanteric fractures were treated with an additional TSP super-imposed on the regular DHS at our institution between July 1991 and July 1993. Five patients died before the first follow-up, one patient was lost to follow-up, and another patient refused follow-up. Thus, thirty-nine patients were followed for at least twelve months (mean 14 months, range 12 to 20 months). INTERVENTION: The fractures treated were classified according to the OTA classification, which is based on the AO classification. Seventeen were 31-A2.2, seven were 31-A2.3, and fourteen were 31-A3.3 fractures. RESULTS: Lateralization of the greater trochanter was successfully prevented in all fractures. Limited fracture impaction was found in 90 percent (n = 35) of the patients with telescoping of 9.5 millimeters (range 0 to 30 millimeters), resulting in mean limb shortening of 5.37 millimeters (range 0 to 14.9 millimeters). Four patients suffered limb shortening exceeding fifteen millimeters (range 15.6 to 21.3 millimeters). Functional results were excellent and good in 87 percent of patients and fair in 13 percent according to the Salvati-Wilson score. All fractures had healed six months after the operation. Three complications required a secondary procedure: one from not inserting a second screw parallel to the gliding hip screw to prevent rotation of the head-neck fragment ("antirotation screw"), one because of deep infection, and one because of a refracture after premature implant removal. CONCLUSION: In unstable pertrochanteric fractures with small or missing lateral cortical buttress, the addition of a TSP to the DHS effectively supports the unstable greater trochanter fragment and can prevent rotation of the head-neck fragment. Excessive fracture impaction and consecutive limb shortening was prevented by this additional implant in 90 percent of these patients.

Adult↗

PubMed1996

On the origin of benzene, toluene, ethylbenzene, and the xylenes in virgin olive oil--further results.

Investigations into the sources of contamination of virgin olive oil by gasoline components were concluded. Olives on the tree contained volatile aromatic hydrocarbons at concentrations exceeding those corresponding to the equilibrium with the environment. Present knowledge indicates that up to 10 micrograms/kg of benzene and 250 micrograms/kg for the sum of benzene, toluene, and the C2-benzenes must be considered as possible background concentrations. Aside from the oil mills, the rooms for intermediate storage of the olives were found to be an important source of contamination by gasoline vapours, since they often contain vehicles and other gasoline-driven engines. Parking of a small, hot grass mower into a similar room released an amount of gasoline that was sufficient to contaminate the oil in olives above the proposed limit by a factor of 100. Recommendations are derived for the producers to avoid contamination of olive oil with gasoline components.

Benzene↗

PubMed1995

On the origin of benzene, toluene, ethylbenzene and xylene in extra virgin olive oil.

Concentrations of benzene, toluene, C2-benzenes and styrene were determined in olives and the oils produced thereof, as well as at various intermediate steps during production. Concentrations were compared to those found in samples of air taken from the olive grove and the olive mills. In an exposition experiment in the laboratory, olives absorbed aromatic compounds, approaching saturation corresponding to the partition coefficient between air and oil. However, concentrations in olives delivered to the mills were 4-10 times higher than expected from the analysis of the air in the olive grove. In the olive mills, concentrations were increased further by a factor of up to 2 because of uptake from air which contained high concentrations of aromatics. Styrene concentrations strongly increased during storage of crushed olives at ambient temperature, which confirms the hypothesis that styrene is a product of metabolism.

Absorption↗

PubMed1995

[MRI and oncoscintigraphy with 99m-Tc-MIBI in the follow up of thyroid cancer].

Magnetic resonance imaging (MRI) and 99mTc-MIBI oncoscintigraphy are new procedures for the detection of recurrent differentiated thyroid cancer. We evaluated the utility of both techniques compared to ultrasonography, radioiodine scanning, and measurement of serum thyroglobulin in patients with (n = 21) or without suspicion (n = 34) of tumor relapse. Although MRI was most effective in detecting local recurrencies (sensitivity: 100%), additional diagnostic information was only obtained in patients with mediastinal lesions. On the other hand, oncoscintigraphy was less sensitive (67%) but highly specific in differentiating reactive lymph node enlargement from metastatic disease (specificity: 93.5%). Oncoscintigraphy may be used instead of radioiodine scanning in patients with doubtful lymph node findings and spare them withdrawal of TSH-suppressive hormone medication. Routine estimation of serum thyroglobulin proved to be highly efficient in screening for tumor relapse using a cut-off level of 3 ng/ml (accuracy: 100%).

Adult↗

PubMed1994

Determination of organophosphorus insecticides in edible oils and fats by splitless injection of the oil into a gas chromatograph (injector-internal headspace analysis).

Direct injection of oil or fat into a moderately heated injector enables performance of a kind of headspace technique in the injector: oil or fat is diluted 1:1 with acetone and injected into a vaporizing chamber at 200 degrees C. Components, for example organophosphorus insecticides, evaporate from the oil film on the insert wall and are transferred into the column in the splitless mode; the oil slowly flows along the wall to the bottom of the insert and is retained there in a kind of a bag. Using a flame photometric detector, detection limits are below 10 micrograms/kg.

Chromatography, Gas↗

PubMed1994

[Attenuation effects in 99mTc-MIBI stressed myocardium 360 degree SPECT: a comparison of the supine and prone positions].

Due to the higher photon energy of 99mTc as compared to 201Tl attenuation effects are expected to be less prominent in SPECT imaging using 99mTc-labelled isonitriles. Reduced 99mTc-MIBI uptake has been observed especially in male patients despite low probability of coronary artery disease. 56 patients were investigated in prone and supine position after bicycle exercise. Inclusion criterium was the identical location of the ROI with maximal tracer uptake in prone and supine imaging. In prone position 99mTc-MIBI uptake was significantly higher in the posterior wall as compared to supine imaging (p < .001). The underlying cause of the apparent increase in tracer uptake of the posterior wall was a decrease in count density in the region of maximal uptake (p < .01) while the count densities in the posterior wall were unchanged (p = NS). Relative uptake values in apical and septal regions of the anterior wall significantly decreased in prone imaging. SPECT imaging in prone position is useful in minimizing attenuation artifacts. However, because a deterioration in the anterior wall cannot be excluded, studies that compare the sensitivities and specificities for the different coronary arteries are required before general prone imaging can be recommended.

Adult↗

PubMed1994

Significance of defect severity in technetium-99m-MIBI SPECT at rest to assess myocardial viability: comparison with fluorine-18-FDG PET.

UNLABELLED: The pathophysiological significance of 99mTc-MIBI uptake at rest for assessing myocardial viability in patients with coronary artery disease (CAD) is still controversial. Therefore, we studied the relationship of 99mTc-MIBI uptake at rest and preserved or absent uptake of 18FDG as assessed with PET in 111 consecutive patients after overnight withdrawal of their antianginal medication. METHODS: Each ventricle was evaluated in 13 segments derived from 25 regions of interest (ROIs) in short-axis cuts and 18FDG uptake was normalized to the intraindividual normal reference ROI (ROI with maximal = 100% 99mTc-MIBI uptake). Segments with a normalized 18FDG uptake > 70% were defined as viable while segments with a 18FDG uptake < 50% were defined as nonviable. RESULTS: Five to 11% of segments with 99mTc-MIBI uptake at rest < or = 30% of peak activity were viable and 80%-84% nonviable. Of moderate to severe 99mTc-MIBI defects at rest (31%-70% of peak), 13%-61% were viable. Segmental 99mTc-MIBI uptake and normalized 18FDG uptake were linearly correlated (r = 0.61, n = 1443, p < 0.001). In segments revealing severely reduced 99mTc-MIBI uptake (< or = 50% of peak) the correlation was considerably lower (r = 0.44, n = 295, p < 0.001). CONCLUSIONS: In patients with CAD, 99mTc-MIBI uptake underestimates myocardial viability in comparison to 18FDG-PET. Myocardial 99mTc-MIBI uptake therefore appears to reflect myocardial blood flow rather than myocardial viability. Patients with moderate and severe 99mTc-MIBI defects at rest may benefit from additional metabolic PET imaging prior to final therapeutic decisions.

Adult↗

PubMed1993

[Contamination of hazel nuts and chocolate by mineral oil from jute and sisal bags].

Before spinning, jute and sisal fibres are treated with a batching oil commonly consisting of a raw mineral oil fraction. Such oil is transferred to foods packed into jute or sisal bags, i.e. primarily cocoa beans, hazelnuts, coffee, almonds, oil seeds, and rice. Concentrations in the foods easily exceed 100 mg/kg. Chocolate may be affected several-fold: cocoa beans as well as hazelnuts and almonds may be contaminated.

Cacao↗

PubMed1993

[Osteomyelitis today--diagnostic imaging and therapy].

Plain radiography, bone scan and especially in infants sonography belong to the primary imaging methods for posttraumatic osteomyelitis. For further diagnostic check up of osteomyelitis CT, MRI and leukocyte scintigraphy are excellent methods. Treatment of posttraumatic osteomyelitis is today a combination of operation, local and systemic antibiotic therapy.

Adolescent↗