[Methyl-11C]thymidine positron emission tomography in tumoral and non-tumoral cerebral lesions.

Background: No ideal radiopharmaceutical exists for positron emission tomography (PET) that fulfills all clinical requirements for the study of brain tumors.

Purpose: The usefulness of a recently developed PET tracer, [methyl-11C]thymidine ([methyl-11C]TdR) is explored in brain tumors.

Patients And Methods: Twenty patients with confirmed tumoral and non-tumoral brain lesions were investigated with [methyl-11C] TdR PET.

Relationship between etomidate plasma concentration and EEG effect in the rat.

Purpose: The effect-plasma concentration relationship of etomidate was studied in the rat using electroencephalographic changes as a pharmacodynamic parameter.

Methods: Etomidate was infused (50 mg/kg/h) in chronically instrumented rats (n=6) until isoelectric periods of 5 s or longer were observed in the electroencephalogram (EEG). The EEG was continuously recorded during the experiment and frequent arterial blood samples were taken for determination of etomidate plasma concentrations.

Vagus nerve stimulation for medically refractory epilepsy; efficacy and cost-benefit analysis.

Introduction: Vagus nerve stimulation is a novel treatment for patients with medically refractory epilepsy, who are not candidates for conventional epilepsy surgery, or who have had such surgery without optimal outcome. To date only studies with relatively short follow-up are available. In these studies efficacy increased with time and reached a maximum after a period of 6 to 12 months.

CART: a controlled algebraic reconstruction technique for electron microscope tomography of embedded, sectioned specimen.

Reconstruction of thick, embedded, sectioned material has to cope with the restricted tilt view of the electron microscope, with information not stemming from the object of interest in the projections, with aberrations of the objective lens and with a distorted relationship between the projected densities in the micrographs and the specimen mass densities due to incoherent electron interactions within the specimen. Micrograph densities over a full tilt-range show in general an averaged mass increase which is more than should be expected from the cosine dependency of the tilt-angles of the projections. The hereby presented reconstruction technique finds a solution for the under-determined system by a controlled algebraic iteration procedure.

Antibiotic resistance of native and faecal bacteria isolated from rivers, reservoirs and sewage treatment facilities in Victoria, south-eastern Australia.

The incidence of resistance to ampicillin, chloramphenicol, kanamycin, nalidixic acid, neomycin and streptomycin was significantly greater (P < 0.001) in native heterotrophic bacteria than in Escherichia coli isolated from a range of sites along the Yarra River in south-eastern Australia. There was no significant difference in the incidence of resistance between native and faecal bacteria to tetracycline.

Design and analysis issues for crossover designs in phase I clinical studies.

To assess the efficacy of potential new drugs in the initial phase of clinical research, one must use an efficient design that satisfies conditions to guarantee the safety of the subjects. For a parallel design, a two-period crossover design, two three-period crossover designs, and a Latin square design with three periods, we compared variances of estimators based on a mixed analysis of variance model. The proposed three-period crossover designs turned out to be only slightly less efficient than the Latin square design, which is not capable of satisfying the necessary safety conditions.

Intra- and interobserver variability of MRI-based volume measurements of the hippocampus and amygdala using the manual ray-tracing method.

We studied the intra- and interobserver variability of volume measurments of the hippocampus (HC) and the amygdala as applied to the detection of HC atrophy in patients with complex partial seizures (CPE), measuring the volumes of the HC and amygdala of 11 normal volunteers and 12 patients with presumed CPE, using the manual ray-tracing method. Two independent observers performed these measurements twice each using home-made software. The intra- and interobserver variability of the absolute volumes and of the normalised left-to-right volume differences (deltaV) between the HC (deltaV(HC)), the amygdala (deltaV(A)) and the sum of both (deltaV(HCA)) were assessed.

Single-voxel proton MR spectroscopy and positron emission tomography for lateralization of refractory temporal lobe epilepsy.

Purpose: We compared the metabolic information obtained from single-voxel proton MR spectroscopy and positron emission tomography (PET) in patients with temporal lobe epilepsy.

Methods: Twenty-nine patients with temporal lobe epilepsy were screened for metabolic abnormalities with both proton MR spectroscopy and PET. Lateralization with MR spectroscopy was possible by using NAA/(Cho+Cr) and an asymmetry index.

Recent and future evolutions in NeuroSPECT with particular emphasis on the synergistic use and fusion of imaging modalities.

Recent and future evolutions in neuroSPECT apply to radiopharmaceuticals techniques and the synergistic use of different imaging modalities in the work-up of neurological disorders. The introduction of Technetium labelled perfusion tracers, which could pass the intact blood-brain barrier, together with the implementation of the tomographic principle, by making the conventional gamma camera rotating, enabled estimation of regional cerebral blood flow and indirectly of local brain metabolism. In addition at present Thallium-201 and Tc-99m sestaMIBI allow functional detection of viable tumor tissue, without interference from previous surgery or radiotherapy as seen using CT-scan or MRI.

Effect of photoperiod on body mass, and daily energy intake and energy expenditure in young rats.

In this experiment we investigate the effect of photoperiod on locomotor activity, body mass, food intake, growth efficiency (relationship between body mass change and food intake), energy expenditure, and body composition in growing Wistar rats. Two groups of animals were subjected to either a long, LD 18:6 (n = 8) or short photoperiod, LD 6:18 (n = 7), during a period of 190 days after weaning. Activity, body mass, food intake, and energy expenditure were measured during the study, as well as body composition at the end of the experiment.

Value of single-voxel proton MR spectroscopy in temporal lobe epilepsy.

Purpose: To study the value of different parameters derived from single-voxel proton MR spectroscopy of the mesial temporal lobes in the lateralization of the epileptogenic zone in patients with temporal lobe epilepsy.

Methods: We studied 12 healthy volunteers and 21 patients with temporal lobe epilepsy refractory to medical treatment, which was clearly lateralized with electroencephalography (EEG) and MR imaging. The mesial temporal lobes were investigated with single-voxel proton MR spectroscopy using a point-resolved spectroscopic sequence with an echo time of 135 milliseconds.

Dipole modeling in epilepsy surgery candidates.

Purpose: The validity and clinical significance of dipole modeling in epilepsy surgery candidates is not fully established.

Patients And Methods: Interictal and ictal dipole modeling was performed in 43 patients with refractory complex partial seizures (CPS) and intracranial structural abnormalities demonstrated with optimum magnetic resonance imaging (MRI: space-occupying, n = 15; atrophic, n = 26; dysplastic, n = 2). Video-EEG monitoring showed CPS in all patients.

Dipole modelling and intracranial EEG recording: correlation between dipole and ictal onset zone.

This study includes 11 patients (3 males, 8 females) with mean age of 29 years (range: 15-42 years) who underwent a presurgical evaluation for refractory complex partial seizures (CPS). In all patients, neuroimaging (1.5 T optimum-MR) demonstrated intracranial structural abnormalities (space-occupying: n = 2; atrophic: n = 8; dysplastic: n = 1) and video-EEG monitoring showed CPS, because of discrepancies in the non-invasive examinations, all underwent additional intracranial EEG monitoring.

Evaluation of transferrin and gallium-pyridoxal isonicotinoyl hydrazone as potential therapeutic agents to overcome lymphoid leukemic cell resistance to gallium nitrate.

Gallium nitrate is active against lymphoma and bladder cancer; however, little is understood about tumor resistance to this drug. Transferrin, the iron transport protein, increases gallium uptake by cells, whereas pyridoxal isonicotinoyl hydrazone (PIH), an iron chelator, transports iron into cells. Therefore, we examined whether these metal transporters would increase the cytotoxicity of gallium in gallium nitrate-resistant CCRF-CEM cells.

Three-point repositioning of axes: three-dimensional alignment procedure for electron microscope tomography using three markers.

A description is given of a new procedure to align series of tilted graphs, made with an electron microscope, for computer tomographic purposes. The procedure uses the coordinates of three projected markers to calculate parameters needed for the reconstruction. To that end the procedure computes the direction of the tilt-axis, the translation and rotation parameters, the tilt-angle of every micrograph, and the spatial coordinates of the individual markers with their centre of gravity as origin of the coordinate system.

Variations in the fluorescence intensity of intact DAPI-stained bacteria and their implications for rapid bacterial quantification.

As current techniques for the quantification of bacteria are laborious and often imprecise, instrumental approaches such as sedimentation field-flow fractionation (SdFFF) are attractive. In this technique, fluorogenic dyes specific for nucleic acids are used to identify bacterial cells. Bacterial biomass can be quantified directly with SdFFF if the specific fluorescence of bacterial cells is constant.

Epilepsy surgery in Belgium, the Flemish experience.

Between January 1992 and June 1995, 160 patients were presurgically evaluated for medically refractory epilepsy by the Epilepsy Monitoring and Surgery Team at the University Hospital of Gent. All these patients underwent a comprehensive presurgical evaluation, including extensive neurological history and examination, video-EEG monitoring of interictal EEG and habitual seizures, CT and optimum MR. In a large subgroup of these patients a comprehensive neuro-psychological examination and interictal 18FDG-PET were performed.

Late-onset epileptic seizures in patients with leukoaraiosis: a positron emission tomographic study.

Leukoaraiosis, found on computed tomographic scans of the brain, is suspected to be of ischemic origin and is frequently associated with progressive decline of cognitive functions in elderly persons. Some of them also develop late-onset epilepsy. The present positron emission tomographic study investigates if these seizures in mentally nonaffected patients with leukoaraiosis are related to an underlying ischemic process.

Interictal and ictal dipole modelling in patients with refractory partial epilepsy.

Fifteen patients (7 men, 8 women) with mean age of 34 years and mean duration of refractory partial seizures of 17 years were included in a presurgical evaluation protocol. Neuroimaging (CAT, 1.5 T MR) demonstrated intracranial structural lesions (space-occupying: n = 9; atrophic: n = 6) and video-EEG monitoring showed complex partial seizures in all patients.

EM-tomography of section collapse, a non-linear phenomenon.

Using back projection for reconstruction and tilt series of Epon or Lowicryl embedded and sectioned material, we demonstrated: (1) a reduction in thickness of 50% for Epon and 80% for Lowicryl sections, and (2) a non-uniform density distribution along the electron-optical axis in sections. The highest density was found at the vacuum exposed side of the section. The formvar side of the section showed a similar increase in density, but not to the same extent.

An MR protocol for presurgical evaluation of patients with complex partial seizures of temporal lobe origin.

Purpose: To find an optimal diagnostic protocol for the presurgical MR evaluation of patients with temporal lobe epilepsy.

Methods: MR imaging in 14 healthy subjects and 25 consecutive patients with temporal lobe epilepsy was performed in paracoronal sections perpendicular to the hippocampi with T1-weighted inversion recovery and T2 weighting. Volume measurements of the hippocampus/amygdala complex were performed and a multiecho sequence yielded T2-calculated images.

Follow-up of cognitive functioning in patients with small cell lung cancer.

Purpose: Study of the course of possible treatment-related cognitive impairment in patients with small cell lung cancer.

Methods And Materials: Thirty-two consecutive patients with small cell lung cancer underwent successive neurologic and neuropsychologic examinations until 5 months after prophylactic cranial irradiation, and in their pretherapeutic condition were compared to matched controls. Patients with brain metastases were excluded from this study.