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Biomedical subjects

J Van de Walle

Publications and source records attributed to J Van de Walle.

At least 19 recordsLinked to original sources
PubMed2005

"Safe" Coulomb excitation of 30Mg.

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion."

Journal Article↗
PubMed2004

Mie scattering of magnetic spheres.

The Mie scattering intensity of a magnetic sphere has been derived by extending the classical Mie scattering approach to a media where the dielectric constant is no more a real number but a tensor with a gyrotropic form. Using a perturbation method the propagation equations of the electromagnetic field are derived. For an incident plane wave the magnetization effect could be detectable. The Mie scattering intensity is analyzed for special incident wave configurations, in particular, for the case where the magnetic field of the incident plane wave is polarized along the magnetization direction. This magnetization effect is most important for the finger pattern of the backscattering intensity. Magnetic Mie scattering is still significant for a magnetic sphere of radius larger than 10 nm.

Journal Article↗
PubMed2003

Monte Carlo model of the Elekta SLiplus accelerator: validation of a new MLC component module in BEAM for a 6 MV beam.

A new component module (CM), called MLCE, has been implemented in the BEAM program. The CM takes into account the particular 'tongue-and-groove' design of the Elekta multi-leaf collimator (MLC) and the air gap between the leaves. The model was validated by two series of measurements and simulations. The first benchmarking series focuses on the interleaf leakage and the intraleaf transmission. The measurement showed a total transmission through the MLC of 1.42% of the open field dose. Two Monte Carlo (MC) simulations were made, the first with the new CM MLCE (inclusive of air gap) and the second with the CM MLCQ (exclusive of air gap), which is available in the BEAM distribution. When the air gap between the leaves was determined by varying the parameters of the leaf geometry within tolerance limits on the technical drawing, the total measured transmission of 1.42% was well reproduced by the CM MLCE. In contrast, MC simulations with MLCQ showed that the transmission through the MLC calculated without the interleaf leakage is only 44% of the total transmitted radiation. The relevance of the detailed MLC modelling was demonstrated also by studying the 'adjacent' tongue-and-groove effect, where two adjacent (not opposing) leaves are complementary, opened or closed. The two complementary leaf settings were simulated both with the CM MLCE and MLCQ. A comparison with measurements was made. In regions covered by two or more leaves, the dose increased by 14% for two leaves and by 40% for more than two leaves when the interleaf leakage was included in the transmission. The tongue-and-groove effect was perfectly reproduced by the MLCE module.

Algorithms↗
PubMed1998

Age- and sex-related 99Tcm-DMSA renal uptake at 24 h in children with a normal scintigram.

We performed a retrospective study to determine the age- and sex-related normal values of absolute 99Tcm-DMSA uptake at 24 h in children with normal kidneys. Of the 576 scintigrams performed between 1993 and 1996, 136 (272 kidneys) were classified as 'normal' by two independent observers on the basis of the presence of a smooth cortical outline, the absence of cortical loss, relative uptake in the range 45-55% and normal echographic parenchymal findings. The 136 scintigrams were divided into eight groups based on the children's age: Group I, < 1 month (2 boys); Group II, 1-3 months (6 boys, 8 girls); Group III, 4-7 months (7 boys, 6 girls); Group IV, 8-12 months (8 boys, 8 girls); Group V, 13-24 months (14 boys, 4 girls); Group VI, 25-36 months (6 boys, 13 girls); Group VII, 37-120 months (13 boys, 19 girls); Group VIII, 121-180 months (8 boys, 10 girls). In contrast to the results of Morris et al. using absolute 99Tcm-DMSA uptake at 4-6 h, we found that combined left and right kidney uptake increased until age 8 months (Group I, 22.0 +/- 6.7%; Group II, 45.9 +/- 5.0%; Group III, 50.8 +/- 5.0%; Group IV, 56.9 +/- 8.5%; P = 0.019), after which it reached a plateau (Group V, 55.4 +/- 7.3%; Group VI, 60.1 +/- 7.8%; Group VII, 62.0 +/- 5.0%; Group VIII, 62.4 +/- 6.3%). Uptake at 24 h tended to be lower in the girls than in the boys, but this difference was not significant.

Adolescent↗
PubMed1987

Changes in intraocular pressure associated with the administration of propofol.

The effect of propofol on intraocular pressure (IOP) was measured in 25 patients presenting for elective non-ophthalmological surgery when propofol was used for the induction and maintenance of anaesthesia (together with 67% nitrous oxide in oxygen, and vecuronium). Normocapnia was maintained. After induction of anaesthesia, intraocular pressure was significantly lower than the baseline value; during maintenance IOP never exceeded the preinduction value. There was a temporary decrease in arterial pressure after induction. In nine patients a cutaneous flush was observed and in seven patients there was discomfort on injection. Spontaneous movement in 20% and hiccup in 12% of the patients were observed at the time of tracheal intubation.

Adult↗
PubMed1986

The neuromuscular blocking action of vecuronium in normal patients and in patients with no renal function and interaction vecuronium-tobramycin in renal transplant patients.

The new short acting steroid muscle relaxant vecuronium was tested clinically in 42 surgical patients and compared in three different groups of patients: normal patients, renal graft patients who received tobramycin preoperatively and other anephric patients undergoing surgery. Twenty-five percent recovery of initial twitch height as measured by NTM was significantly longer in the renal graft group than in the two other groups where recovery time is normal. Cardiovascular parameters were recorded before and after the injection of vecuronium. Reversal of the neuromuscular block was spontaneous or pharmacologically evoked by neostigmine. Clinical recovery was complete in all patients and there was no residual block.

Adult↗
PubMed1984

The use of continuous arteriovenous hemofiltration in intensive care medicine.

Acute renal failure still remains an important and challenging problem in the ICU. Hemodialysis is not always feasible because of hemodynamic instability in critically ill patients. In this circumstances continuous arteriovenous hemofiltration (CAVH) can be an efficient alternative as this method has less detrimental hemodynamic effects. Moreover, within certain limitations, CAVH proves to be an effective "artificial kidney" (control of body fluid, electrolyte and acid-base homeostasis and uremia) and this without serious side-effects. Special emphasis is made on the problem of anticoagulation, which can cause life-threatening complications in posttraumatic and surgical patients. A protamine infusion on the venous line can diminish these complications.

Acute Kidney Injury↗
PubMed1983

[Anesthesia in geriatric patients].

Old age brings a considerable number of anatomical and physiological changes which are important in the preparation and conduction of geriatric anesthesia. These changes are briefly reviewed in this article. If the preoperative preparation and the choice and conduct of anesthesia are handled with care, the operative mortality and morbidity of aged patients should not be materially greater than that of other age groups. Aged patients need careful supervision in the postoperative period. Pulmonary and cardiovascular complications are more frequent and more dangerous in this age-group. Their early recognition and treatment as soon as they appear will reduce the postoperative mortality. Therefore, a short or longer stay in a well-equipped intensive care unit may he highly beneficial.

Aged↗
PubMed1980

The treatment of cancerpain with analgesic drugs.

The use of analgesic drugs is only one part of a multidisciplinary approach which offers also other possible palliative procedures for pain therapy. Pain complaints are placed against the background of terminal illness. The use of analgesic drugs and their combinations is discussed, with a short reference to their mechanism of action. The way of adminstration may have some impact on the efficacy of the analgesic regimen. Side effects and concomitant medication are reviewed.

Amphetamines↗
PubMed1980

Six years experience with an emergency department based mobile emergency care delivery system.

The purpose of mobile emergency care is to provide on a basis of 24 hours out of 24, the necessary material (ambulances wiwth resuscitation equipment) and personnel (ambulance-drivers, nurses and doctors), in order to care for the victim of accident or sudden illness on the spot and during transport to the hospital. The experience gained with a mobile emergency care delivery system, organized within the Emergency Department of the University Hospital Sint-Rafaël Leuven, Belgium, is analyzed and discussed. The conclusions of the study stress the advantages, as far as economics and efficiency are concerned, of the integration of the mobile emergency care delivery system in the emergency department of the highly specialized university hospital.

Adolescent↗
PubMed1980

Pulmonary function tests before and after open heart surgery.

Eighty seven patients, undergoing open heart surgery, were tested preoperatively and postoperatively (on the first, the second, the sixth and the eighth postoperative day) with a Vitalograph spirometer on Forced Vital Capacity (FVC), Forced Expiratory Volume at 1 second (FEV1), Forced Expiratory Flow (FEF) and Forced Midexpiratory Flow (FMF). Preoperative values in this patients were surprisingly good compared with the values calculated from the nomograms presented by Kamburoff et al. (1). Nevertheless three high risk groups were found. Postoperative values for each measured parameter were very low especially on the first and second postoperative day. This easy practicable method gives a more objective approach of the restricted pulmonary function of patients undergoing open heart surgery.

Adult↗
PubMed1978

Computer assisted monitoring in intensive medicine.

Intensive Medicine is always associated with the problem of handling the mass and assuring the quality of information on vital signs, fluid and blood balance, laboratory data, physiological calculations, etc., required in patient care. A computer based monitoring system for intensive care was introduced in 1973 at the Academic Hospital in Leuven. The basic software was developed at the Peter Bent Brigham Hospital of the Harvard Medical School and the medical division of the Hewlett Packard Company; the computer used was a H.P. 2100 central processor with 32K of core memory. Initially, the program allowed mainly acquisition, storage and retrieval of bedside monitored and manual data of cardiac and circulatory function. Very soon however, the software was extended and modified by the division of "Medical Informatics" in order to meet new or different requirements. In the present situation our vision on the use of computer-assisted monitoring has changed and our present program has been extended as follows : 1. On-line collection and retrieval of bedside monitored data including heart rate, arterial blood pressure (systolic-diastolic-mean) left atrial pressure, central venous pressure, pulmonary artery pressure, intracranial pressure. Trend analysis of those data, with calculation of mean values, standard variation and corresponding t-tests. 2. Computer assistance in performing time consuming calculations on off-line data such as : -- clearance-values (renal function), -- temperature-correction of blood-gasvalues, -- hour-to-hour fluid balance, including calculation of in-sensible losses, -- blood-balance. 3. Data transmission of laboratory results as soon as available in the central laboratory through a direct link between laboratory and I.T.U. 4. Computer assisted E.C.G. analysis. The three first objectives are realised, on-line E.C.G.-analysis is being developed. The same computer serves the remotely located medical and coronary care units and one bed in the emergency department. An assessment of computer assistance in intensive therapy, on nursing labor and on quality of patient care is made.

Clinical Laboratory Techniques↗