Biomedical subjects

J M Caille

Publications and source records attributed to J M Caille.

At least 19 recordsLinked to original sources

PubMed1999

Dose and scanning delay using USPIO for central nervous system macrophage imaging.

RATIONALE AND OBJECTIVES: In experimental allergic encephalomyelitis (EAE), central nervous system (CNS) macrophage imaging is achievable by MRI using AMI-227 an ultra-small particle iron oxide contrast agent at a dose of 300 micromol/kg Fe. The objective was to test the feasibility at the human recommended dose of 45 micromol/kg Fe. METHODS: Two groups of EAE rats were tested with AMI-227 using 45 and 300 micromol/kg Fe respectively. Following i.v. injection of AMI-227, they were scanned after a delay of 4-6 and 20-24 h. RESULTS: With a high dose of AMI-227, all animals showed low signal intensity related to iron-loaded macrophages in the CNS. At low dose no abnormalities were found in the CNS. Furthermore, a delay of 4-6 h failed to demonstrate abnormalities even at high dose. CONCLUSIONS: Dose, scanning delay after administration and blood half-life are major parameters for T2* CNS macrophage imaging.

Animals↗

PubMed1999

[Cerebral panthrombophlebitis in a paucisymptomatic patient].

In most cases, extensive cerebral venous thrombosis present themselves with a severe clinical outcome and poor prognosis. We present the case of a 59-years-old patient with a slight rather unrevealing symptoms but suffering from a cerebral thrombosis impacting on both superficial and deep venous system. The etiologic assessment revealed activated protein C resistance. Clinical evolution under systemic anticoagulation was prompt, with complete repermeabilization of the various venous structures.

Activated Protein C Resistance↗

PubMed1998

Early structural changes in acute MS lesions assessed by serial magnetization transfer studies.

BACKGROUND: Whether acute MS lesions are primarily inflammatory or demyelinative is unresolved. Our study examined acute MS lesions longitudinally by quantitative magnetization transfer (MT), an MRI technique that identifies tissue integrity and destruction. METHODS: Four MS patients were studied by serial MRI including MT, conventional T2-weighted images, and postgadolinium T1-weighted images for 9 to 12 months. In 15 new lesions, the MT ratio (MTR) was calculated retrospectively. RESULTS: In 13 lesions, a marked decrease in the MTR was present early during the first 2 months after the onset of the lesion and was followed by a variable increase. In two other lesions, the MTR progressively declined. CONCLUSIONS: These results suggest that major early structural changes compatible with demyelination and followed by remyelination and gliosis, or by continuous demyelination, occur in new MS lesions. The various MTR profiles provide in vivo confirmation of the current knowledge of the progression in MS lesions. Furthermore, MTR may be used to monitor in vivo drug efficacy in new MS lesions.

Adult↗

PubMed1997

Magnetization transfer imaging in AIDS-related brain diseases.

MT makes it possible to characterize tissue destruction in several CNS diseases, including AIDS-related diseases such as PML or HIV encephalitis. MR may be helpful in establishing diagnosis, disease burden, prognosis, and therapeutic efficacy. MT may also contribute to the investigation of the natural history of the diseases. The other application is in improving contrast after the injection of gadolinium chelates. This contrast improvement can be achieved routinely on any device and may be a good alternative to other methods, such as increasing dose or delay.

AIDS Dementia Complex↗

PubMed1996

Efficacy and safety of iobitridol versus iohexol for contrast-enhanced CT of the head.

PURPOSE: The efficacy and adverse reactions of iobitridol versus iohexol in contrast-enhanced CT (CECT) of the head were investigated. MATERIAL AND METHODS: This double-blind randomized parallel study compared the clinical and biological safety of iobitridol and iohexol (350 mgI/ml), administered intravenously (1 ml/kg) to 276 patients undergoing CECT of the head. Vital signs were assessed just before after injection, and 24 hours after. A biologic examination was performed before and after injection. Both groups were comparable at inclusion. RESULTS AND CONCLUSION: The within-group variation for vital signs after injection and 24 hours after was not clinically relevant and no significant difference was evident between treatment groups. The incidence of adverse events was similar in both groups (11.0% for iobitridol and 7.1 % for iohexol), consisting most often of a sensation of warmth. Biologic parameters remained stable and did not differ significantly between groups. The quality of imaging was rated good or excellent in 70% of cases and a very high diagnostic discrimination was achieved (98%). Iobitridol compared favorably with iohexol for head CECT.

Adolescent↗

PubMed1995

Lateralization of prefrontal activation during internal mental calculation: a functional magnetic resonance imaging study.

1. Functional magnetic resonance imaging (fMRI) at 1.5 T was used to investigate the lateralization of prefrontal cortex activity during internal mental calculation in 16 human volunteers (8 right-handed and 8 left-handed). Subjects were asked to perform two different tasks: 1) a serial subtraction of prime numbers and 2) a control task in which they mentally recited numbers. 2. Signal modifications were regularly observed in the prefrontal cortex (Brodmann's area 46) during the serial subtraction of prime numbers, whereas the number listing task poorly activated the same areas. 3. In right-handed subjects, activation was clearly lateralized in the left dorsolateral prefrontal cortex, whereas a frequent bilateral activation was found in left-handed subjects. 4. We conclude that prefrontal activation during mental calculation is lateralized in a manner similar to that reported during linguistic tasks, i.e., a clear lateralization in right- but not in left-handed subjects.

Adult↗

PubMed1995

Lysolecithin-induced demyelination in primates: preliminary in vivo study with MR and magnetization transfer.

PURPOSE: To study bystander demyelination in multiple sclerosis with an experimental in vivo model of toxic demyelination. METHODS: Toxic demyelinating lesions were created in two monkeys by injection of lysophosphatidylcholine in the centrum semiovale. Follow-up was done clinically and with serial MR studies, including T2-weighted and gadolinium-enhanced T1-weighted images and measurement of magnetization transfer ratio, until the animals were killed at days 14 and 34, respectively. Light and electron microscopy analysis was compared with MR data. RESULTS: Interval measurement of magnetization transfer ratio during the course of the experiment revealed a maximum decrease at day 7 to day 8, associated with the greatest clinical manifestations. The lowest values of magnetization transfer ratio correlated with histopathologic findings of myelin and axon destruction. Magnetization transfer ratio measurements appear to be sensitive to macromolecular destruction and specifically to membrane disorganization. At no time was gadolinium enhancement observed in this model of toxic demyelination. CONCLUSION: Preliminary results of this study indicated that magnetization transfer is a good technique to follow in vivo matrix destruction in brain parenchyma lesions. The results suggest also that phases of toxic demyelination in multiple sclerosis might not show gadolinium enhancement. Differentiation between demyelinating activity and associated inflammation in multiple sclerosis lesions should be considered in further in vivo work.

Animals↗

PubMed1992

[Methods for measuring spinal cord blood flow].

This study aimed to review the techniques used most currently for measuring spinal cord blood blow flow (SCBF) in animals, i.e. the hydrogen clearance, labelled microspheres, 133Xe clearance and 14C-antipyrine autoradiographic methods. All four techniques may only be used in animals, because of their invasiveness. Flow figures varied greatly with the method, the spinal level at which measurements were carried out, and the species of animal. However, results tend to suggest that SCBF is very similar to cerebral blood flow in that it is controlled by chemical, autoregulatory and metabolic factors. Approaches to measuring SCBF in man may be made using stable xenon-enhanced computed tomographic imaging (Xes-CT) in the same way as for measuring cerebral blood flow. The calculation of SCBF is based on Fick's principle transformed by Kety and Schmidt. After a reference CT section has been obtained, twelve 8 mm thick sections are carried out whilst the patient breathes a 30% xenon-70% air/oxygen mixture. This series of views enables the SCBF to be calculated in four steps. Quantitative analysis in eight human subjects gave a mean SCBF of 58.8 +/- 5.96 ml x 100 g-1 x min-1. However, this method has a low signal to noise ratio. Moreover, the qualitative analysis of the parametric views of flow demonstrate tissue heterogeneity, partly due to the patient's movements (breathing movements). However, the method is non invasive, safe, and reproducible. As it can measure very low values of blood flow, the study of ischaemic spinal lesions is made possible, although some technical and software improvements are still required.

Adult↗

PubMed1992

Early effect of gadopentetate and iodinated contrast media on rabbit kidneys.

RATIONALE AND OBJECTIVES: The authors compared the physiologic and nephrotoxic effects of the magnetic resonance imaging contrast medium gadopentetate with two conventional radiographic contrast media. METHODS: Rabbits were injected intravenously with one of the following solutions: 1) gadopentetate (0.1 M); 2) iohexol (300 mg I/mL); 3) metrizoate (300 mg I/mL); and 4) NaCl (0.9%). Blood samples were taken before and 5, 15, 45, 90, and 180 minutes after injection of the solutions and were analyzed for creatinine, aldosterone, and contrast media levels. Urine was sampled before and 1, 2.5, and 5 hours after injection of the solutions, and creatinine, leucine amino peptidase (LAP), alkaline phosphatase (ALP), gamma glutaryl transferase (GGT), and N-acetyl beta-D-glucosaminidase (NAG) activities were quantified. RESULTS: Contrast media clearance was similar for gadopentetate, iohexol, and metrizoate. Plasma aldosterone was significantly higher in the two groups injected with iodinated contrast agents compared with the gadopentetate and saline groups in the 3-hour samples. During the 5 hours after injection, the excretion of brushborder enzymes LAP, ALP, and gamma GT was significantly higher for all contrast media compared with pre-contrast values and 0.9% NaCl controls. NAG, a lysosomal enzyme from tubular cells, showed a significant increase compared with pre-contrast values for all contrast media. CONCLUSIONS: Intravenous injection of gadopentetate in rabbits showed nephrotoxicity of the same order as that of conventional iodinated contrast media.

Aldosterone↗

PubMed1992

Multihormonal response to corticotropin-releasing hormone in inferior petrosal sinus blood of one patient with Cushing's disease: comparison with in vitro secretion of the tumoral corticotropes.

A multihormonal response to CRH during inferior petrosal sinus sampling in patients with Cushing's disease has recently been described. Whether it reflects multihormonal secretion by the corticotropic adenoma, or secretion by non-tumorous adjacent cells via paracrine mechanisms remains debatable. We have compared the effect of CRH on ACTH, GH, PRL and TSH secretion during inferior petrosal sinus sampling with its effect on the in vitro secretion of the corticotropic adenoma after excision in one case of Cushing's disease. Before CRH injection in vivo results show significant central-peripheral gradients for all hormones but only ACTH lateralized to the side of the tumor. After CRH administration, the petrosal concentrations of all hormones increased preferentially on the side of the adenoma resulting in significant intersinus gradients: 8.1 for ACTH, 2.0 for GH, 1.8 for PRL and 1.5 for TSH. In vitro results: the adenoma cells were immunostainable for ACTH only. In culture, they secreted ACTH only. Addition of CRH to the culture induced a mean increase of 160% in ACTH secretion but GH, PRL and TSH remained undetectable. Our results favor the hypothesis that the multihormonal response to CRH seen during inferior petrosal sinus sampling in Cushing's disease reflects a paracrine stimulation of the adjacent non-tumorous pituitary cells by the corticotropic adenoma.

Adenoma↗

PubMed1992

MRI and cervicobrachial neuralgia.

Recent improvements in magnetic resonance imaging techniques have altered our choices in the exploration of cervicobrachial neuralgia (CBN). The use of high-field machines, new acquisition sequences and paramagnetic contrast media has increased the sensitivity and specificity of the MRI method in the detection of degenerative lesions responsible for CBN. These new techniques are essentially based on gradient-echo sequences can be acquired in two or three dimensions, and each of them has its own advantages and drawbacks, but their performance is sufficient for MRI to be now considered a reliable and non-traumatic exploratory method for CBN. Performed after standard radiography, MRI tends to be the first-choice examination in the preoperative evaluation of cervical radiculopathies and myelopathies.

Adult↗

PubMed1991

Magnetic resonance spectroscopy and metabolism. Applications of proton and 13C NMR to the study of glutamate metabolism in cultured glial cells and human brain in vivo.

Nuclear magnetic resonance (NMR) spectroscopy was used to study the metabolism of cells from the central nervous system both in vitro on perchloric acid extracts obtained either from cultured tumoral cells (C6 rat glioma) or rat astrocytes in primary culture, and in vivo within the human brain. Analysis of carbon 13 NMR spectra of perchloric acid extracts prepared from cultured cells in the presence of NMR [1-13C] glucose as substrate allowed determination of the glutamate and glutamine enrichments in both normal and tumoral cells. Preliminary results indicated large changes in the metabolism of these amino acids (and also of aspartate and alanine) in the C6 cell as compared to its normal counterpart. Localized proton NMR spectra of the human brain in vivo were obtained at 1.5 T, in order to evaluate the content of various metabolites, including glutamate, in peritumoral edema from a selected volume of 2 x 2 x 2 cm3. N-acetyl aspartate, glutamate, phosphocreatine, creatine, choline and inositol derivative resonances were observed in 15 min spectra. N-acetyl-aspartate was found to be at a lower level in contrast to glutamate which was detected at a higher level in the injured area as compared to the contralateral unaffected side.

Animals↗

PubMed1991

Study of correlation between intradiscal pressure and magnetic resonance imaging data in evaluation of disc degeneration. Therapeutic issue with percutaneous nucleotomy.

Intradiscal pressure and volume measurements using discomanometry were correlated to features of degeneration noted with magnetic resonance (MR) imaging in 36 discs in patients scheduled for percutaneous nucleotomy. Discomanometric data (intradiscal pressure and degree of pressure loss at 0 and 60 seconds after intradiscal infusion, area under the pressure curve, and discal volume) were not correlated with the MR data (degree of disc height loss and degree of signal intensity loss on T2-weighted images). Results of nucleotomy were strongly correlated with discomanometric data but not with the studied MR factors. Discomanometry by evaluating the physical status of discs, may predict results of percutaneous nucleotomy and consequently play a major role in patients selection.

Female↗

PubMed1991

Usefulness of the corticotropin-releasing hormone test during bilateral inferior petrosal sinus sampling for the diagnosis of Cushing's disease.

Inferior petrosal sinus blood sampling for ACTH measurement (IPSS) is used for the differential diagnosis of ACTH-dependent Cushing's syndrome and for the preoperative location of pituitary microadenomas. Intermittent ACTH secretion from pituitary adenomas may result in insignificant differences between petrosal and peripheral ACTH levels at the time of sampling. Thus, pituitary stimulation during IPSS may improve the procedure. The aim of the study was to evaluate the usefulness of CRH injection in combination with IPSS. Twenty-two patients with Cushing's disease (CD; 5 macroadenomas, 16 microadenomas, and 1 corticotroph hyperplasia) and 5 patients with ectopic ACTH syndrome were studied. Bilateral IPSS was successfully carried out on 25 patients. Patients with ectopic ACTH syndrome had, before and after CRH injection, central to peripheral ACTH gradients below 1.7. Four patients with CD had basal gradients below 1.4. After CRH administration all patients with CD had gradients above 3.2. Despite correct location of central catheters, the predicted location of pituitary microadenomas was erroneous in 41% of the cases. It was not improved after CRH injection. In conclusion, the combination of CRH injection with IPSS was useful for the differential diagnosis of ACTH-dependent Cushing's syndrome, as it increased the discrimination of the procedure. On the contrary, it was useless for the preoperative location of pituitary microadenomas, which was poorly predicted by IPSS.

ACTH Syndrome, Ectopic↗

PubMed1991

[CT X-ray measurement of cerebral blood flow by stable xenon. Methodology and applications].

The measurement of cerebral blood flow by stable xenon computerized tomography is a tridimensional method that offers an excellent spatial resolution. The quantitative estimation of the cerebral blood flow is based on Fick's principle, transformed by Kety and Schmidt, using stable xenon as indicator, which is an inert and freely diffusible gas. The limitations of this method are related to the necessity for the patient to remain completely immobile during the examination, the low signal/noise ratio and the impossibility of measuring cerebral metabolism. By contrast, this method represents a real advantage in the diagnosis and prognosis of cerebral pathology: it allows the acquisition of a precise cartography of superficial and deep regional blood flows; it can reveal zones under the functional perfusion threshold thank to its capacity to measure very low blood flows; it allows the obtention of additional information in pathologies of tumoral, ischemic or degenerative origin by measuring the partition coefficient. Moreover, this technique is reliable, non invasive and reproducible. Advantages of such measurement are illustrated in revealing epileptic foci in partial seizures resistant to medical treatment, in the prognosis of cerebrovascular accidents and in the therapeutic evaluation of drugs used in animal experiments.

Blood Flow Velocity↗

PubMed1990

Neurotoxicity of iohexol vs iopamidol in lumbar myelography. Clinical, electrophysiological and brain CT scan correlations.

The potential neurotoxicity of iohexol and iopamidol in lumbar myelography was investigated in 20 patients using three criteria: clinical symptoms, EEG recordings with spectral analysis and CT scans of the brain. There was no significant difference in clinical side-effects between the two groups (Iopaminol, Iohexol). In 10 patients (iopaminol 4, iohexol 6) CT scans revealed an important penetration of the contrast media into the subarachnoid spaces at 3 hours and into the cerebral cortex at 24 hours. This cerebral contamination was unrelated to the headaches experienced by the patients or to the electrophysiological disturbances observed. Spectral analysis in brain-contaminated subjects showed a reduction of delta, beta 1 and beta 2 bands with iohexol. This reduction suggests that EEG activation is less pronounced with this agent than with iopaminol.

Brain↗

PubMed1990

[Protocol for preparation, anesthesia and monitoring in therapeutic angiography].

The procedures involved in cerebral and medullary embolization produce special problems for the anesthesiologist. Some imperatives must be followed in order to minimize the high neuroradiological risks associated with these long and repetitive procedures. The first of these imperatives is sedation, which throughout the procedure should be sufficient, although not narcotic enough to prevent neurological evaluations. The use of a benzodiazepine (Midazolam) in conjunction with an analgesic (Alfentanil) that is rapidly eliminated answers this need. The prescription of vasodilatator agents depends on the location of the embolization. Calcium channel blockers should be used following embolism of the internal carotid while nitrate derivatives are recommended after embolism of the external carotid. Reduction of the risk of thrombosis is accomplished by perfusion with anti-sludge or, with exception to therapeutic procedures involving hemostasis, by perfusion with acetylsalicylic acid. Following evaluation of 105 procedures in 75 patients it is concluded that this sedation produces reliable results and allows the procedure to be performed with maximal security.

Adolescent↗

PubMed1989

Normal and disrupted lumbar longitudinal ligaments: correlative MR and anatomic study.

The posterior and anterior longitudinal ligaments of the lumbar spine appear on magnetic resonance (MR) images as thin lines of very low signal intensity in all spin-echo sequences. They cover the periphery of the outer fibers of the anulus fibrosus on sagittal images. The lumbar spine of 17 patients with 19 disk herniations was prospectively evaluated with MR imaging, and these findings were correlated with surgical findings. At surgery the posterior ligament was found to be disrupted in eight cases and intact in 11. Absence of a low-signal peripheral line around the herniated nucleus pulposus (HNP) was the most reliable sign of ligament rupture (no false-negative or false-positive findings). The peripheral line appeared to be interrupted in four cases, two of which were falsely positive. The two false-positive cases were related to a chemical shift artifact between epidural fat and the HNP. Presence of a normal and continuous peripheral line outlining the HNP excluded ligament disruption. The overall sensitivity for detecting disruption was 100%, and the specificity was 78%.

Adult↗