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Biomedical subjects

P Brunner

Publications and source records attributed to P Brunner.

At least 19 recordsLinked to original sources
PubMed2006

A multifrequency magnetic induction tomography system using planar gradiometers: data collection and calibration.

We developed a 14-channel multifrequency magnetic induction tomography system (MF-MIT) for biomedical applications. The excitation field is produced by a single coil and 14 planar gradiometers are used for signal detection. The object under measurement was rotated (16 steps per turn) to obtain a full data set for image reconstruction. We make measurements at frequencies from 50 kHz to 1 MHz using a single frequency excitation signal or a multifrequency signal containing several frequencies in this range. We used two acquisition boards giving a total of eight synchronous channels at a sample rate of 5 MS s(-1) per channel. The real and imaginary parts of DeltaB/B(0) were calculated using coherent demodulation at all injected frequencies. Calibration, averaging and drift cancellation techniques were used before image reconstruction. A plastic tank filled with saline (D = 19 cm) and with conductive and/or paramagnetic perturbations was measured for calibration and test purposes. We used a FEM model and an eddy current solver to evaluate the experimental results and to reconstruct the images. Measured equivalent input noise voltage for each channel was 2 nV Hz(-1/2). Using coherent demodulation, with an integration time of 20 ms, the measured STD for the magnitude was 7 nV(rms) (close to the theoretical value only taking into account the amplifier's thermal noise). For long acquisition times the drift in the signal produced a bigger effect than the input noise (typical STD was 10 nV with a maximum of 35 nV at one channel) but this effect was reduced using a drift cancellation technique based on averaging. We were able to image a 2 S m(-1) agar sphere (D = 4 cm) inside the tank filled with saline of 1 S m(-1).

Calibration↗
PubMed2005

Percutaneous treatment in patients presenting with malignant cardiac tamponade.

The percutaneous treatment of pericardial effusion resulting in cardiac tamponade has undergone an evolution in recent years with the use of less invasive drainage techniques in selected cases. To determine optimal therapy modalities for oncology patients with malignant pericardial tamponade (MPT), the authors review their institutional experience with percutaneous needle puncture routes, means of imaging-guided drainage and percutaneous management of the pericardial fluid effusion (pericardial sclerosis and balloon pericardiotomy). Advantages and limits of the percutaneous techniques will be compared to the surgical treatment.

Balloon Occlusion↗
PubMed2005

[Arrhythmia and sport].

Sports arrhythmia has gained wide attention with the mediatization of the death of famous sports stars. Sport strongly modifies the structure of the heart with the development of left ventricular hypertrophy which may be difficult to differentiate from that due to doping. Intense training modifies also the resting electrocardiogram with appearance of signs of left ventricular hypertrophy whereas resting sinus bradycardia and atrioventricular conduction disturbances usually reverts upon exertion. Accordingly, arrhythmia may develop ranging from extrasystoles to atrial fibrillation and even sudden death. Recent data suggest that if benign arrhythmia may be the result of the sole intense training and are reversible, malignant ventricular arrhythmia and sudden death mostly occur in unknown structural heart disease. Hypertrophic cardiomyopathy is amongst the most frequent post mortem diagnosis in this situation. Doping is now present in many sports and further threatens the athlete in the safe practice of sport.

Arrhythmias, Cardiac↗
PubMed2003

Media calcification, low erythrocyte magnesium, altered plasma magnesium, and calcium homeostasis following grafting of the thoracic aorta to the infrarenal aorta in the rat--differential preventive effects of long-term oral magnesium supplementation alone and in combination with alkali.

Calcifications in arterial media are clinically well documented, but the role played by magnesium in pathophysiology and therapy is uncertain. To clarify this, an animal model in which the juxtacardial aorta was grafted to the infrarenal aorta, and the subsequent calcifications in the media of the graft and their response to oral supplementation with three magnesium-containing and alkalinizing preparations was investigated. Groups of highly inbred rats were formed as follows: sham-operation (Sham, n = 12), aorta transplantation (ATx, n = 12), ATx + magnesium citrate (MgC, n = 12), ATx + MgC + potassium citrate (MgCPC, n = 12), ATx + MgC + MgCPC (MgCPCSB, n = 12). At 84 (+/-2) days after ATx with or without treatment the following observations were made: (1) weight gain and general status were normal; (2) ATx rats developed massive media calcification, mineral accumulation in the graft, decreased erythrocyte magnesium and plasma parathyroid hormone, and increased plasma ionized magnesium and calcium, and uric acid; (3) Mg-treated rats developed variable degrees of metabolic alkalosis, but only MgCPCSB supplementation prevented calcifications. Additional findings after ATx alone were: imbalance in endothelin and nitric oxide production, the mineral deposited in media was poorly crystallized calcium phosphate, calcium exchange between plasma and graft, and bone resorption were unchanged. The superior anti-calcification effect of MgCPCSB was characterized by complete restoration of normal extracellular mineral homeostasis and uric acid, but sub-optimal normalization of erythrocyte magnesium. It was concluded that in the rat: (1) ATx causes loss of cellular magnesium, excess of extracellular magnesium and calcium in the presence of apparently unchanged bone resorption, and increased uricemia; (2) ATx facilitates enhanced influx of calcium into vascular tissue, leading to calcium phosphate deposition in the media; (3) ATx-induced calcification is prevented by dietary supplementation with a combination of magnesium, alkali citrate and bases. Although the described circulatory model of media calcification in the rat requires further investigation, the data allow ascribing a fundamental role to magnesium and acid-base metabolism.

Animals↗
PubMed2003

[Ventricular tachycardia "in salvoes"].

The term of ventricular tachycardia "in salvoes" describes electrophysiographic appearances of several consecutive ectopic ventricular beats without interposition of sinus rhythm. This is an intermediate arrhythmic state between isolated ventricular extrasystoles and sustained ventricular tachycardia. The generally accepted definition of the term "sustained" implies a duration of over 30 seconds or poor haemodynamic tolerance. Strictly speaking, the term "salvoe" has no precise definition in cardiology. In the 1996 edition of the Petit Robert French dictionary, the term is defined as the simultaneous discharge of guns or successive blasts of canons. The Delaware medical dictionary does not provide a French definition of the term "salvoe". In practice, we use the term tachycardia in salvoes in the same meaning as ventricular tachycardia. Schematically, in clinical practice, two situations may be encountered. In the first case, salvoes of VT are recorded in apparently normal hearts; they are not life-threatening and, though often nearly asymptomatic, they may pose therapeutic problems. In the second case, the arrhythmia occurs in a diseased heart, with a low ejection fraction, in which the essential problem is the vital prognosis.

Electrocardiography↗
PubMed2001

Design and evaluation of a cryogenic soft tissue fixation device -- load tolerances and thermal aspects.

Mechanical studies of soft connective tissues often encounter methodological difficulties, particularly in the secure fixation of the tissues. A simple, inexpensive technique which allowed stable cryofixation of soft tissues in uniaxial loading machines was developed. The cryogenic fixation device was evaluated in terms of its fixation strength and the temperature gradients within the tested tissues. Human patellar ligaments and quadriceps tendons were tested successfully to an average failure load of 2219N (S.D. 448N) with mid-substance failures occurring in 90% of the specimens. The temperature gradients within porcine flexor and extensor tendons were determined and found to exhibit a typical diffusion profile. The fixation quality was dependent upon the initial block temperature and the desired testing time. In summary, the cryofixation device presented here is an effective tool for soft tissue fixation but the effect of this type of fixation on internal tissue temperatures and possible testing times must be acknowledged.

Adult↗
PubMed2001

Successful transarterial embolization of idiopathic renal arteriovenous fistula.

A case of idiopathic renal arteriovenous fistula in a 46-year-old woman presenting intensive right renal colic associated to massive hematuria is reported. The renal arteriography confirmed the diagnosis and embolization of the fistula was performed. The transarterial embolization was successful no recurrence is observed after one year follow-up.

Arteriovenous Fistula↗
PubMed1999

Pulmonary embolism caused by acrylic cement: a rare complication of percutaneous vertebroplasty.

A pulmonary embolus of acrylic cement was present in a 41-year-old woman with Langerhans' cell vertebral histiocytosis (LCH) after percutaneous vertebroplasty. Chest radiograph and CT confirmed pulmonary infarction and the presence of cement in the pulmonary arteries. She was treated with anticoagulants, and responded favorably. This rare complication occurred because perivertebral venous migration was not recognized during vertebroplasty. Adequate preparation of cement and biplane fluoroscopy are recommended for vertebroplasty.

Adult↗
PubMed1998

Effect of cyclic preconditioning on the tensile properties of human quadriceps tendons and patellar ligaments.

Preconditioning of soft tissues has become a common procedure in tensile testing to assess the history dependence of these viscoelastic materials. To our knowledge, this is the first study comparing tensile properties of soft tissues-before and after cyclic preconditioning with high loads. Sixteen quadriceps tendon-bone (QT-B) complexes and 16 patellar ligament-bone (PL-B) complexes from a young population (mean age 24.9 +/- 4.4 years) were loaded to failure with a deformation rate of 1 mm/s. Half of the QT-B and the PL-B complexes underwent 200 uniaxial preconditioning cycles from 75 to 800 N at 0.5 Hz before ultimate failure loading. High-load preconditioning was made possible by the development of a highly reliable and easy-to-use cryofixation device to attach the free tendon end. PL-B complexes were more influenced by preconditioning than the QT-B complexes. Ultimate failure load, stiffness at 200 N and stiffness at 800 N were significantly higher for PL-B complexes after preconditioning, while the structural properties of QT-B complexes exhibited no significant alterations. The values of the mechanical properties like Young's modulus at 200 N and 800 N were much higher for both preconditioned specimen groups. In addition, ultimate stress was augmented by preconditioning for PL-B complexes. Hysteresis and creep effects were highest during the first few loading cycles. More than 160 cycles were needed to reach a steady state. Beyond 160 cycles there was no further creep, and hysteresis was almost constant. Creep values were 2.2% of the initial testing length for the QT-B and 3.2% of the initial testing length for the PL-B complexes. The effect of cyclic preconditioning seems to be caused by progressive fiber recruitment and by alterations of the interstitial fluid milieu.

Anterior Cruciate Ligament↗
PubMed1998

[Congenital hepatic fibrosis. Five cases with late occurrence in adults].

Congenital hepatic fibrosis (CHF), is an autosomal recessive disease, presenting principally in childhood with portal hypertension and/or cholangitis, and often associated with renal malformations. The forms presenting later in adults are rare, and illustrated herein by 4 cases with dominant cholangitis, and one latent form. Biological tests and radiological imaging are often normal. The histopathologic diagnosis, sometimes difficult on liver needle biopsy is based on fibrous enlargement of portal areas, with numerous and tortuous bile ducts, lined by regular, cuboidal epithelium. Interportal fibrosis can mimic cirrhosis. In CHF, cholangitis are favoured by intrahepatic biliary dilatation, sometimes related to Caroli's disease, associated in 25% of cases. Suppurative complications, sometimes fatal explain the severity of cholangitis forms of CHF, contraindicating inopportune cholangiography and biliary surgery.

Age of Onset↗
PubMed1997

[10 years after Chernobyl--radioactivity of mother's milk-- measurements from Tirol, Tibet and Nepal].

10 years after the Chernobyl disaster gamma radioactivity from Cs-137 was determined in 53 breast milk samples from Tyrol, as well as 9 samples from Tibet and 2 from Nepal by means of a gamma-spectrometer with a germanium detector. In contrast to the values obtained within a few days, and again 1 year after the nuclear plant catastrophe, all samples from Tyrol showed gamma radioactivity levels (median 0.07 nCi/l; range 0.02-0.20 nCi/l) which were now below the limit laid down for baby food in Austria (0.3 nCi/l-11.1 Bq). The samples from Tibet and Nepal registered a slightly higher level of gamma radioactivity (median 0.16 nCi/l; range 0.16-0.41 nCi/l).

Animals↗
PubMed1997

Interstitial laser photocoagulation of osteoid osteomas with use of CT guidance.

PURPOSE: To evaluate interstitial laser photocoagulation (a minimally invasive percutaneous technique of thermal destruction of deep-seated tumors, with low-power laser energy) in local destruction of osteoid osteoma, with computed tomographic (CT) guidance. MATERIALS AND METHODS: Fifteen patients (age range, 8-48 years) with presumed osteoid osteoma were treated with CT-guided interstitial laser photocoagulation of the nidus. A high-power semiconductor diode laser (805 nm) with a 400-microm optical fiber was used. The fiber was introduced into the nidus through an 18-gauge needle. Around the fiber tip, well-defined coagulative necroses from 5 to 9 mm (energy delivery, 400-1,000 J) were obtained. RESULTS: Fourteen patients had complete pain relief, which was apparent within 24 hours in eight patients. One patient had recurrence of pain after 6 weeks. The remaining nidus was treated a second time, with complete relief. Treatment was unsuccessful in one patient, and surgical excision was performed. Daily activities were not restricted after the intervention. All patients were followed up for more than 1 year, with no sign of recurrence. The only notable complication was a mild reflex sympathetic dystrophy of the wrist in one patient. Sclerosis of the nidus was observed 4-6 months after the procedure. CONCLUSION: Percutaneous interstitial laser photocoagulation of osteoid osteoma seems to be a promising, simple, precise, and minimally invasive alternative to traditional surgical and percutaneous ablations.

Activities of Daily Living↗
PubMed1996

[Questions of habilitation-rehabilitation in diabetes mellitus].

As a result of the up to date treatment the life quality of diabetic patients is improved, their life span is prolonged. The authors recite the guidelines of vocational guidance and disability evaluation of diabetics. It is generally accepted that patients treated by diet alone may choose any profession, their lifestyle need not differ from that of healthy people. Well educated diabetic patients on oral antidiabetics or insulin, who have near normoglycemic blood sugar levels, can follow the lifestyle of a healthy individual; yet they should avoid occupations where their own or others lives might be put in danger. The authors recite effective departmental orders about the questions that influence the lives of diabetic patients-for example drivers licence, sports facilities for diabetics- and are the most frequently encountered by experts. Problems of rehabilitation that arise during the management of diabetics are also discussed.

Adult↗
PubMed1996

Benign fibrous mesothelioma of the pleura: MR study and pathologic correlation.

Benign fibrous mesothelioma of the pleura is a rare tumor of mesodermal origin. We describe the MR findings in three pathologically proven cases. All three tumors were imaged by MR as well-circumscribed lesions with smooth margins in contact with the pleura, but without chest wall invasion. Their low signal intensity on T1- and T2-weighted sequences reflect their fibrous nature. In one case a pedicle connecting the tumor to the chest wall was visualized on a sagittal MR scan. In two cases gadolinium-enhanced T1-weighted gradient echo sequences revealed intense contrast uptake by the tumor correlated with the intratumoral hypervascularization noted by histologic examination. Although the number of cases presented is small, MR seems to be the most accurate imaging modality in the assessment of the diagnosis.

Aged↗
PubMed1996

Quadriceps tendon and patellar ligament: cryosectional anatomy and structural properties in young adults.

Structural tensile properties analyses of 10-mm-wide central sections of quadriceps tendon-bone (QT-B) and bone-patellar ligament (B-PL) complexes from young male donors (mean age 24.9 years, range 19-32 years) were complemented by a cryosectional analysis: each QT-B complex was composed of the segment of the quadriceps tendon with the proximal half of the patella attached, each B-PL complex was composed of the distal half of the patella with the patellar ligament attached. A servohydraulic materials testing machine was used to assess ultimate failure load of 16 unconditioned and 16 preconditioned QT-B and B-PL complexes at an extension rate of 1 mm/s. Ligaments/tendons were preconditioned during 200 cycles from 50 to 800 N at 0.5 Hz. On cryosections the quadriceps tendons were significantly longer and thicker and exhibited a significantly larger bony attachment area than the patellar ligaments. Cross-sectional areas of 10-mm-wide, full-thickness, central parts of unconditioned quadriceps tendons were significantly greater and measured 64.6 +/- 8.4 mm2 with respect to the cross-sectional area of patellar ligaments, measuring 36.8 +/- 5.7 mm2 (P < 0.0025). Ultimate failure loads for unconditioned complexes resulted at 2173 +/- 618 N for QT-B complexes and at 1953 +/- 325 N for B-PL complexes (P = 0.43). Ultimate failure load values measured 2353 +/- 495 N for preconditioned QT-B complexes and 2376 +/- 152 N for preconditioned B-PL complexes, respectively (P = 0.77). Despite the fact that initial testing length, thickness, cross-sectional shape and area of unconditioned QT-B and B-PL complexes were significantly different, displacement at ultimate load, energy to failure and total energy were not. In terms of ultimate tensile strength, the 10-mm-wide central part of the QT-B complex compared favourably to the tensile properties of the human femur-anterior cruciate ligament-tibia complex from a comparable young age group. The evidence from anatomic, cryosectional and structural properties analyses suggests that the QT-B complex may be a valuable and versatile adjunct to the surgeon's armamentarium in reconstructive cruciate ligament surgery.

Adult↗
PubMed1996

Tritium intake by exposure to plastic case watches.

In recent years tritium has been used in plastic case watches as permanent light sources on watch dials. To measure the release of tritium through the plastic cases, 82 different waterproofed watches were immersed in a water bath for 24 h, and the tritium concentration of the water was measured. The mean tritium release rate was 24,400 Bq d(-1) ranging from 110-162,000 Bq d(-1). Parallel measurements were made to determine the tritium concentration in the urine of 108 wearers of plastic case watches. The mean tritium concentration in urine was 197 Bq L(-1) up to 1,133 Bq L(-1). The whole body dose resulting from exposure to plastic case is negligibly small but given the pathway of skin absorption, the annual skin dose is 3-4 times higher than the dose limit for the public. Plastic case watches are collector's items and are often kept with other watches in glass cabinets or other containers. Storage of a large number of such watches in one container causes tritium to diffuse through the plastic cases and to contaminate watches that did not contain tritium at first. If the container is more or less airtight, the tritium concentration in the container and the tritium release rate from the watches can reach levels up to 4 MBq d(-1).

Humans↗
PubMed1996

Percutaneous laser disk decompression under CT and fluoroscopic guidance: indications, technique, and clinical experience.

The aim of percutaneous laser disk decompression (PLDD) is to vaporize a small portion of the nucleus pulposus of an intervertebral disk, thereby reducing the volume and pressure of a diseased disk. This minimally invasive technique can be performed in patients who need surgical intervention for disk herniation with leg pain. PLDD is usually performed under fluoroscopic guidance with or without diskoscopy. However, it can also be performed under dual computed tomographic (CT) and fluoroscopic guidance as an outpatient procedure. CT and fluoroscopic guidance increases the safety and accuracy of PLDD, with high precision of instrument guidance, direct visualization of nucleus pulposus vaporization, and reduced risk of complications. Of 119 patients with lumbar disk herniation treated with PLDD under CT and fluoroscopic guidance, 91 (76.5%) had a good or fair response. PLDD performed with CT and fluoroscopic guidance appears to be a safe and effective treatment for herniated intervertebral disks.

Adolescent↗