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B Aubert

Publications and source records attributed to B Aubert.

At least 19 recordsLinked to original sources
PubMed1994

[Dosimetry with Imatron].

Although the Imatron is based on a technology different from that of conventional CT scanners, its physical principle is comparable. For this reason dosimetric studies were carried out in the same manner that is by employing small thermoluminescent dosimeters. The results obtained with this technique for the four specific protocols of the Imatron indicated surface doses between 0.7 and 15.7 cGy and between 0.1 and 7.2 cGy at surface of the slice. The weakest doses were recorded during cardiac exams for which this type of CT scanner was designed and developed. This highest doses were delivered for scans of the head region.

Humans↗
PubMed1994

A technique of measuring the precision of an MR-guided stereotaxic installation using anatomic specimens.

PURPOSE: To develop a method for direct measurement, using anatomic specimens, of the precision of MR-guided stereotaxic location and to describe its application to a 1.5-T MR unit with a Leksell stereotaxic frame. METHODS: Small pieces of gelfoam (1 X 1 X 1 mm), soaked in gadopentetate dimeglumine, were stereotaxically introduced into formalin-fixed human heads using a Leksell D (three experiments) or G (nine experiments) stereotaxic frame. The head and the frame were then introduced into a 1.5-T MR unit. The target coordinates (as set on the stereotaxic frame by one investigator) were then compared with the MR-determined stereotaxic coordinates (calculated independently by another investigator). The imprecisions Ex, Ey, and Ez in each direction were defined as the differences between the calculated and the chosen coordinates. RESULTS: Regarding the three targets studied with the D frame, mean imprecision Ex was 1.08 +/- 0.50 mm (mean +/- SEM), Ey 0.83 +/- 0.58 mm, and Ez 0.75 +/- 0.25 mm. For the nine targets studied with the G frame, Ex was 0.48 +/- 0.17 mm, Ey 0.69 +/- 0.14 mm, and Ez 0.82 +/- 0.13 mm. Statistical analysis of the results showed no significant difference between Ex or Ey and half the size of a pixel, indicating that, in the axial plane, stereotaxic MR precision is limited only by pixel size. A statistically significant difference was observed in the coronal plane between Ez and half the size of a pixel, but it must be stressed that Ez remained smaller than 1 mm. CONCLUSION: MR-guided stereotaxic location can be used with confidence for most diagnostic, functional, and therapeutic procedures.

Calibration↗
PubMed1993

Usefulness of technetium-99m hydroxymethylene diphosphonate scans in localizing bone metastases of differentiated thyroid carcinoma.

Iodine-131 is uniquely able to demonstrate iodine uptake of differentiated thyroid carcinoma (DTC), but precise localization may be difficult, especially in the thorax, due to the quality of image resolution with 131I and the lack of anatomical landmarks. When bone metastases do not show radioiodine uptake bone scintigraphy can be used to detect them. We studied two groups of patients. In group 1, 15 patients with known bone metastases of DTC were treated with 3.7 GBq 131I. After 4 or 5 days, technetium-99m hydroxymethylene diphosphonate (HMDP; 740 MBq) was injected and a whole-body scan with simultaneous acquisition of 131I and 99mTc-HMDP images was carried out using a large field of view gamma camera fitted with a high-energy collimator. Technetium uptake was abnormal in 47 of 63 localizations, being increased in 29 foci, decreased in 7 and heterogeneous in 11. The superimposition of 131I and 99mTc-HMDP scans permitted an accurate localization in 80% of spine metastases and in 46% of osseous thoracic localizations, even in the presence of lung metastases. In group 2, 9 patients, who had bone pain, neurological signs or elevated serum thyroglobulin, had DTC bone metastases without iodine uptake. They received a diagnostic dose of 99mTc-HMDP 3h prior to scintigraphy with a large field of view gamma camera fitted with a low-energy collimator. Technetium uptake was abnormal in 37 of 38 localizations, being increased in 34 foci and decreased in 3. One false-negative was found in a skull metastasis. In both groups of patients, 99mTc-HMDP scans were useful.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma, Follicular↗
PubMed1992

Retrospective evaluation of the dose received by the ovary after radioactive iodine therapy for thyroid cancer.

In an earlier study, we evaluated the frequency of clinical manifestations of ovarian insufficiency after radioiodine therapy for thyroid cancer. We were thus led to consider the dose received by the ovary (DRO) during these treatments. In the literature, this dose is expressed as a function of the activity administered. However, in our study, the disorders were not correlated with the activity administered. Faced with this discrepancy, we have attempted to establish a dosimetric model using the parameters available for each patient. The results obtained show that besides the activity administered, which plays a role, morphological and kinetic factors specific to each individual have an importance that cannot be ignored when addressing this problem.

Female↗
PubMed1992

Malignant pheochromocytoma: clinical, biological, histologic and therapeutic data in a series of 20 patients with distant metastases.

Twenty patients, 16 males and 4 females, aged 11-76 yr, were treated for a metastatic pheochromocytoma at our institution between 1985 and 1990. A neurofibromatosis was associated in 4. Thirteen patients had a unilateral adrenal tumor, 3 had an extraadrenal retroperitoneal tumor, 2 had a bilateral adrenal pheochromocytoma, one had a unilateral tumor with a contralateral medullary hyperplasia and one an adrenal and an extraadrenal pheochromocytoma. Metastases occurred in all patients, at presentation in 11, 10 to 30 months later in 7, and 9 and 28 yr later, respectively in two. Histology did not afford conclusive evidence for malignancy. Catecholamine hyperproduction was present in all, predominantly affecting norepinephrine. Neuron Specific Enolase level was elevated in 11, Neuro-Peptide Y level in 9 and procalcitonin level in 11/18. High dopamine, methoxytyramine and homovanillic acid excretion levels seemed to correlate with large tumors or terminal stage. MIBG uptake was found in 16 after a diagnostic dose and in 1 only after a therapeutic dose. Surgery was performed on primary tumor in 18 and on distant metastase in 10. Iodine-131 MIBG therapy was performed in 11, among whom 9 were evaluable. Cumulative activity ranged from 100 to 711 mCi, in 1 to 6 courses. Symptomatic improvement occurred in 5 patients, stabilization was observed in 3 and tumor partial response in two, which lasted for 28 and 9 months, respectively terminating in a rapidly progressing disease with bone marrow involvement. Moderate myelosuppression occurred in 4 patients. Chemotherapy gave no response in 7 evaluable patients. Fourteen patients died with a median survival of 16 months from diagnosis of metastases (range 3-60). Response to therapy was poor and warrants further cooperative trials.

3-Iodobenzylguanidine↗
PubMed1992

[Prolonged effect against exercise-induced bronchospasm: salmeterol versus sodium cromoglycate].

Nineteen subjects with isolated exercise-induced asthma (FEV1, FEF25-75%, PEFR, FVC greater than 95% predicted values, fall in FEV1 of at least 15% after exercise, typical recent symptoms of exercise-induced asthma, no other treatment) were entered in a multicenter trial carried out in a double blind, double placebo, cross-over manner. After a one-month baseline period, subjects underwent an exercise after inhaling 100 micrograms of salmeterol (n = 12) or 40 mg of sodium cromoglycate (n = 7). Treatments were alternated before the second exercise which took place at least 2 days after the first. Efficacy was assessed by examining changes in FEV1, FEF25-75% after exercise carried out 30 minutes and 7 hours after administering the treatment by comparison with baseline values (assessments done 1, 10 and 30 minutes after exercise, lowest of three values kept for the analysis of each parameter). FEV1 and FEF25-75% were significantly higher 30 minutes after taking salmeterol. Salmeterol was found to be superior to sodium cromoglycate for all parameters 7 hours after administering the drug. Both treatments were well tolerated. This study confirms that the longer duration of effect of salmeterol and its superiority by comparison with the standard treatments of exercise-induced asthma.

Adrenergic beta-Agonists↗
PubMed1991

Use of m-[131I]iodobenzylguanidine in the treatment of malignant pheochromocytoma.

The efficacy and safety of m-[131I]iodobenzylguanidine ([131I]MIBG) were assessed in 15 patients with malignant pheochromocytomas in a nonrandomized, single arm trial, in which patients were treated with [131I]MIBG (SA, 740 megabequerel/mg) every 3 months. Seven of these patients had bone and soft tissue metastases, 4 had only soft metastases, and 4 had only bone metastases. The follow-up period ranged from 6-54 months; the number of doses ranged from 2-11, with 2.9 (78.4 mCi) to 9.25 gigabequerel (GBq) (250 mCi)/administration and a cumulative activity from 11.1-85.90 GBq (300-2322 mCi). The absorbed cumulative dose in tumors ranged from 12-155 Gy. A beneficial effect of the treatment was observed in 9 patients (60%). No complete remission of the disease was observed. Seven patients died during the study, among whom 4 never responded to the treatment. Seven had hormonal responses (4 complete and 3 partial), with a duration ranging from 5-48 months. Among these patients, 4 relapsed, and 3 died within 3 months. Five patients had partial tumoral responses mainly located in soft tissues and for a duration ranging from 29-54 months. All patients with a hormonal response had objective improvement in clinical status and blood pressure. There was no clear-cut relationship between the cumulative dose and the responses. The main side-effect observed in 1 patient with widespread bone metastases after three doses (12.9 GBq) was a pancytopenia, which resolved after treatment was discontinued. This study suggests that repeated [131I]MIBG treatment could be effective in patients with advanced malignant pheochromocytoma.

3-Iodobenzylguanidine↗
PubMed1991

[Ondansetron: a specific 5-HT3 serotonin receptor inhibitor, a new antiemetic in oncology].

Serotonin (5-Hydroxytryptamine) seems to play a dominant role in triggering vomiting induced by cytotoxic agents through the stimulation of 5-HT3 receptors. They have been observed in the GI tract as well as in the brain (area postrema). Ondansetron is a specific antagonist of 5-HT3 serotonin receptors. Its anti-emetic activity is very powerful in the ferret. The availability of an injectable or oral form of this product allows the overall treatment of acute and delayed emesis and its administration is in accordance with different schedules: single IV injection or a continuous 24 hour infusion or repeated IV injection followed by oral treatment. The pharmacokinetics of the drug are as follows: absorption begins about 30 minutes after the administration per os, its biodisponibility is about 60%, its clearance: 20 ml/minute and its elimination half life about 3 hours. Different double blind studies, carried out in parallel groups or in cross over, demonstrated the superiority of ondansetron over metoclopramide in the control of nausea and vomiting, whether or not the chemotherapy contained cisplatin; a more recent study shows also that ondansetron was superior to alizapride and methylprednisolone in combination. Side effects of ondansetron do not include extrapyramidal symptoms but only headaches and constipation. The use of ondansetron improves the well-being of patients receiving chemotherapy and increases protocol compliance.

Animals↗
PubMed1990

Saliva from cystic fibrosis patients contains an unusual form of epidermal growth factor.

Epidermal Growth Factor (EGF) was assayed in saliva collected from control subjects and cystic fibrosis (CF) patients, using both radioimmuno (RIA) and radioreceptor (RRA) assays. An intriguing finding was that the average ratio of the values found by RRA over those obtained by RIA was of 1.7 for normal subjects and of about 0.4 for CF patients. This observation could be understood following gel filtration analysis of EGF-like material in these salivary fluids. Whereas control saliva contained the expected 6 kDa EGF active peptide, the immunoreactive EGF material from CF patients eluted as a polydisperse macromolecular moiety. The poor biological reactivity of this material as assessed by radioreceptor assay suggests that this EGF anomaly may contribute to the physiopathology of cystic fibrosis, especially as the upper gastrointestinal tract differentiated functions may be the target of normal salivary EGF.

Adolescent↗
PubMed1987

Therapeutic use of 131I-metaiodobenzylguanidine (MIBG) in neuroblastoma: a phase II study in nine patients.

Effects of high activities of I 131 meta-iodobenzylguanidine (mIBG) were evaluated in nine children with advanced neuroblastoma. All patients had been previously heavily treated and had either primarily refractory disease or resistant relapse. Twenty-two doses of mIBG labeled with 1.3 to 4 GBq (35-108 mCi) of iodine 131 were administered. Three subjective effects, especially relief of pain, and two objective effects were observed. Transient blood pressure increase was observed once and did not recur after prolongation of the infusion time to 6 hours. A major side effect was bone marrow toxicity, essentially marked by thrombopenia, particularly severe in previously bone-marrow-transplanted patients.

3-Iodobenzylguanidine↗
PubMed1987

[Are auditory prostheses a contraindication to magnetic resonance imaging?].

Prior to the use of nuclear magnetic resonance imaging (NMRI) in patients with metallic ossicular prostheses their compatibility must be investigated with the intense magnetic fields generated by NMRI. Implanted auditory prostheses are an absolute contraindication to NMRI, but an experimental study of its possible interaction with metallic stapedial prostheses has shown absence of their displacement. The artefact induced may alter images of middle ear but do not affect internal auditory canal. Nevertheless, manufacturers should conduct tests of magnetism of prostheses before they are passed as satisfactory.

Cochlear Implants↗
PubMed1985

Antibody-independent interaction between the first component of human complement, C1, and the outer membrane of Escherichia coli D31 m4.

The heptoseless mutant of Escherichia coli, E. coli D31 m4, binds C1q and C1 at 0 degrees C and at low ionic strength (I0.07). Under these conditions, the maximum C1q binding averages 3.0 X 10(5) molecules per bacterium, with a Ka of 1.4 X 10(8) M-1. Binding involves the collagen-like region of C1q, as shown by the capacity of C1q pepsin-digest fragments to bind to E. coli D31 m4, and to compete with native C1q. Proenzyme and activated forms of C1 subcomponents C1r and C1s and their Ca2+-dependent association (C1r-C1s)2 do not bind to E. coli D31 m4. In contrast, the C1 complex binds very effectively, with an average fixation of 3.5 X 10(5) molecules per bacterium, and a Ka of 0.25 X 10(8) M-1, both comparable with the values obtained for C1q binding. C1 bound to E. coli D31 m4 undergoes rapid activation at 0 degrees C. The activation process is not affected by C1-inhibitor, and only slightly inhibited by p-nitrophenyl p'-guanidinobenzoate. No turnover of the (C1r-C1s)2 subunit is observed. Once activated, C1 is only partially dissociated by C1-inhibitor. Our observations are in favour of a strong association between C1 and the outer membrane of E. coli D31 m4, involving mainly the collagen-like moiety of C1.

Cell Membrane↗
PubMed1984

Chemoprophylaxis of malaria in non-immune residents in Dar es Salaam, Tanzania.

The malaria infection rates in non-immune residents of Dar es Salaam on various chemoprophylactic regimens were compared with that (37.1%) in those not taking prophylactic antimalarials. Among 647 people resident in Dar es Salaam for 1-6 years the two groups with the lowest infection rates by person-episodes (2.0% and 1.5%) were those taking proguanil 200 mg daily alone or with chloroquine base 300 mg weekly. Infection rates (16.9% and 14.0%) were also significantly lower than in the no-prophylaxis group in those taking chloroquine base 300 mg weekly combined with 'Fansidar', 'Maloprim' (each one tablet weekly), or proguanil 100 mg daily. No significant reduction in the malaria attack rate was found in those taking chloroquine base 300 mg or 600 mg weekly (31.2%), pyrimethamine 25 mg weekly (27.3%), proguanil 100 mg daily (46.4%), maloprim one tablet weekly (40.4%), or a combination of chloroquine base 300 mg weekly and pyrimethamine 25 mg weekly (27.1%). Similar results were obtained when the infection rates per year of exposure were compared. Proguanil was associated with fewest user complaints and fansidar with most.

Adolescent↗
PubMed1983

Physical requirements of a 59Fe bone marrow distribution digital scanning study.

A method is described to provide whole-body scannings of 59Fe bone marrow distribution using a tungsten-alloy collimator. The physical requirements of this method were determined by means of dedicated phantoms. As we were only interested in bounded 59Fe regions (sacral bone, liver and spleen), it was necessary to subtract the 59Fe activity in the blood. An estimate of this activity was obtained by means of 99mTc-labelled erythrocyte whole-body scanning to which a correction factor K was applied. The independence versus depth was performed by computing geometrical means of prone and supine images. The results of these experiments indicate the possible feasibility of a scanning method for a ferrokinetic study in place of the usual external counting.

Bone Marrow↗
PubMed1983

Feasibility of a 59Fe ferrokinetic study based on bone-marrow scans.

The purpose of this study was to evaluate the feasibility of a method that would use 59Fe quantitative sequential scintigrams together with a few blood samples in place of conventional ferrokinetic studies. To quantitate the efficiency of erythropoiesis or iron deposition sites, the radio-iron blood activity was subtracted by means of a whole body scanning with 99mTc-labelled erythrocytes. The study was performed on 31 patients (36 examinations) and regions of interest were drawn by three physicians on the sacral bone, the liver, the spleen and the femoral bone. To assess the physical feasibility of the scintigraphic method, correlation coefficients were computed between the number of counts of the 59Fe and 99mTc images and the corresponding 99mTc and 59Fe activities. To assess the clinical feasibility, the consistency of the data resulting from the drawing of the ROIs was verified and those of conventional ferrokinetics were introduced and their consistency verified. These assessments suggest that the scintigraphic method can be used in place of the conventional external counting method.

Bone Marrow↗
PubMed1983

[Scanography].

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Brain↗