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Biomedical subjects

J Vion-Dury

Publications and source records attributed to J Vion-Dury.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cerebral metabolic alterations in human immunodeficiency virus-related encephalopathy detected by proton magnetic resonance spectroscopy. Comparison between sequences using short and long echo times.

RATIONALE AND OBJECTIVES: The aim of this study is to evaluate comparatively the metabolic information afforded by proton magnetic resonance (MR) spectroscopy with stimulated-echo acquisition mode (STEAM) (echo time [TE], 20 mseconds) and point-resolved spectroscopy sequence (PRESS) (TE, 135 mseconds) spectra in HIV-related encephalopathy. METHODS: Sixty-three human immunodeficiency virus (HIV) patients and 8 controls were examined by single-voxel proton MR spectroscopy at 1.5 tesla, using both PRESS (TE, 135 mseconds) and STEAM (TE, 20 mseconds) sequences performed during the same MR examination, in the same volume of interest. Cerebral atrophy was quantitated using bicaudate ratio (BCR) and bifrontal ratio (BFR). RESULTS: With the STEAM (TE, 20 mseconds) spectra, mean N-acetylaspartate (NAA)/choline (Cho) and NAA/creatine and phosphocreatine (Cr-PCr) ratios are reduced in acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) patients but not in neuroasymptomatics. The proportion of inositol signal is increased, that of NAA decreased in ADC patients. NAA/Cho and NAA/ Cr-PCr mean values measured with PRESS (TE, 135 mseconds) spectra are significantly reduced in ADC and neuroasymptomatic patients. Bifrontal ratio only correlates with NAA/Cr-PCr and NAA/Cho measured on the PRESS spectrum. PRESS (TE, 135 mseconds) spectra allow a definition of different metabolic patterns in HIV-related encephalopathy. At last, no correlation has been found between the NAA raw signals measured on the PRESS (TE, 135 mseconds) and STEAM (TE, 20 mseconds) spectra obtained in the same MR examination. CONCLUSIONS: STEAM (TE, 20 mseconds) spectra provide more metabolic information-namely an evaluation of glial-neuronal status-than PRESS (TE, 135 mseconds) spectra, which afford a metabolic classification of the HIV-related encephalopathy. Because both sequences afford a similar diagnostic gain, MR spectroscopy examination probably requires spectrum acquisition with both sequences.

AIDS Dementia Complex↗
PubMed1996

[Future path of magnetic resonance spectroscopy in clinical medicine].

The metabolic exploration of skeletal muscle and brain by magnetic resonance spectroscopy (MRS) provides the basis of the main clinical applications of in vivo MRS on humans. Also, high resolution MRS is used in vitro to identify and assay the metabolites contained in physiological fluids (blood, urine, CSF). In these applications, MRS has became and will keep developing as the investigative tool of choice to perform non-invasively "live biochemistry" experiments on organs and tissues.

Body Fluids↗
PubMed1996

A multicenter proton magnetic resonance spectroscopy study of neurological complications of AIDS.

Human immunodeficiency virus (HIV) infection as seen in Europe and the United States has predominantly been contracted through male homosexual sex or intravenous drug abuse. In infected subjects, the brain is frequently affected both clinically and neuropathologically. The aim of this multicenter study has been to evaluate the value of single-voxel proton magnetic resonance spectroscopy (MRS) in the assessment of the neurological complications of acquired immunodeficiency syndrome (AIDS). MRS (voxel size = 8 ml, TR/TE = 1600/135 msec) was performed in 137 HIV-1-seropositive patients and 64 healthy controls without risk factors at three clinical MR sites operating at 1.5 T. The first result of this multicenter trial is that good reproducibility of results among participating sites was found. This demonstrates the reliability and robustness of MRS in the study of in vivo brain metabolism. In HIV patients, there was no significant correlation between metabolite ratios of brain detected by MRS and CDC grouping of patients or CD4 count. In contrast, the variations of brain metabolite ratios (NA/Cr, NA/Cho, and Cho/Cr) were related to the occurrence of encephalopathy, brain atrophy, or diffuse white matter lesions. There was no significant difference in brain metabolites between male homosexual AIDS patients and male intravenous drug user AIDS patients, whatever their neurological status (neurosymptomatic or neuroasymptomatic). Thus, the mode of transmission of HIV infection does not appear to affect the cerebral changes observed in the proton spectra from AIDS patients. Because of its ease of implementation and high information content, single-voxel proton MRS is likely to play a significant role in the evaluation of HIV-related encephalopathies.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Value of Doppler echocardiography in the detection of low-grade rejections after cardiac transplantation.

Modifications of the diastolic parameters pressure half-time (PHT) and isovolumic relaxation time (IVRT), recorded using cardiac Doppler echocardiography (CDE), were studied in 23 heart transplant recipients and compared to the results of 345 endomyocardial biopsies (EMB) performed on the same day. Two different protocols, analyzing respectively (1) a decrease of 20% or more in IVRT and/or PHT with respect to the mean and (2) a decrease of 20% or more in IVRT and/ or PHT with respect to its preceding value, were used to evaluate the efficiency of CDE in diagnosing mild and moderate rejections. When a mild rejection was detected by EMB, a statistically significant decrease was found in the average CDE parameter values of the patient population. However, these variations were weak and did not differ from the spontaneous variations observed in each patient in the absence of rejection. Thus, it is not surprising that the sensitivity of CDE in the detection of mild rejections was very low (45%) using the most sensitive protocol (variations of the parameters from their preceding value). We conclude that CDE alone does not seem to be sufficient to perform the noninvasive diagnosis of low-grade rejections and must be complemented by other noninvasive methods.

Adult↗
PubMed1996

Cerebrospinal fluid metabolic profiles in multiple sclerosis and degenerative dementias obtained by high resolution proton magnetic resonance spectroscopy.

We have analyzed the cerebrospinal fluid (CSF) of 19 patients with multiple sclerosis (MS), 12 patients with degenerative dementia and 17 control patients using in vitro high resolution proton magnetic resonance spectroscopy (MRS) at 400 MHz. The CSF metabolic profile is slightly modified in MS patients (increased lactate and fructose concentrations, decreased creatinine and phenylalanine concentrations) and is not correlated with the intensity of the intrathecal inflammation. Proton MRS of CSF does not differentiate relapsing-remitting MS and primary progressive MS. We have not detected any specific abnormal resonance in native or lyophilized CSF. The CSF metabolic profile of demented patients is much more altered (increased concentration of lactate, pyruvate, alanine, lysine, valine, leucine-isoleucine, tyrosine, glutamine) and is in agreement with a brain oxidative metabolism impairment as already described in Alzheimer's disease. Unassigned abnormal but non specific or constant resonances have been detected on MR spectra of demented patients. CSF inositol concentration is also increased in the CSF of patients with Alzheimer's disease. In vitro high resolution proton MRS of the CSF constitutes a new and original way to explore CSF for the differential and/or early diagnosis of dementias, as a complement to in vivo proton cerebral MRS.

Adult↗
PubMed1995

Phosphorus-31 in vivo magnetic resonance spectroscopy of bone fails to diagnose osteoporosis.

The values of in vivo T1 relaxation time (T1) of phosphorus atoms of wrist bone have been measured by phosphorus-31 magnetic resonance spectroscopy (MRS) in 65 menopausal women separated into three groups: (1) age-matched women without any paraclinical or clinical osteoporosis; (2) patients with paraclinical osteoporosis detected only by dual photonic absorptiometry; and (3) women with clinical osteoporosis with vertebral fractures. No significant differences were found in T1 values in the presence of paraclinical or clinical osteoporosis as compared to control values. No relationships were found among the T1, the value of the Z-score, the value of bone mineral content, the age of patients, the number of their children, and the age of menopause. Phosphorus-31 magnetic resonance spectroscopy of the wrist fails to separate osteoporotic from nonosteoporotic women and cannot be clinically used at this time to perform a noninvasive diagnosis of osteoporosis.

Absorptiometry, Photon↗
PubMed1995

Localised proton magnetic resonance spectroscopy in X-linked adrenoleukodystrophy.

We have performed localised proton magnetic resonance spectroscopy (MRS) of the brain on four patients with X-linked adrenoleukodystrophy (X-ALD). The spectrum is characterised at the beginning of the disease by a decrease in N-acetylaspartate and phosphocreatine-creatine content. Choline is strongly increased, and lactate can be detected in some cases. A proton signal from the CH2 groups borne by free intracellular very long chain fatty acids can also be observed. Later in the disease, the levels of all metabolites, in particular NAA, decrease significantly. The progression of neurometabolism documented by MRS correlates well with MRI and clinical progression on follow-up study. In one case, the metabolic profile recorded by proton MRS was abnormal before any change occurred on MRI. Proton MRS of the brain might be the method of choice for monitoring patients with X-ALD, to screen presumed cases and to study the effects of treatment.

Adolescent↗
PubMed1995

[Magnetic resonance spectroscopy: a new technique for the exploration of brain metabolism in pediatrics].

In vivo nuclear magnetic resonance spectroscopy (MRS) has been developed recently in order to analyze brain metabolism in adults and children. After a short presentation of the methods and of the metabolic signals detected by phosphorus and proton MRS of the brain, the impact of MRS in pediatrics is examined with two main indications: the study of cerebral maturation in normal or pathological neonates, and the study of inborn metabolic encephalopathies. In the near future, brain MRS will be performed routinely after conventional MRI, and will become a valuable metabolic complement to the anatomical evaluation of cerebral pathologies.

Birth Injuries↗
PubMed1995

Study of bone mineralization using phosphorus 31 nuclear magnetic resonance spectroscopy. Results in a population of women with osteoporosis.

The phosphorus 31 nuclear magnetic resonance signal from the wrist bones was studied in controls covering a broad age range and in postmenopausal osteopenic women with or without osteoporosis. The signal, which was obtained in less than 10 minutes, was broad (30 ppm) and easy to distinguish from muscle signals. Results were reproducible in a given subject. Signal intensity increased with the diameter of the wrist. Because of difficulties with in vivo quantification, we were unable to derive an accurate measurement of bone mineral content from the bone signal. Analysis of in vivo relaxation times of bone phosphorus atoms failed to demonstrate significant differences between osteoporotic subjects and same-age controls. These apparently disappointing findings may be ascribable to technical problems, to which solutions may be within reach. Our study provides information on the difficulties of this method and on the modalities of use of 31P nuclear magnetic resonance spectroscopy for evaluation of disorders of phosphorus and calcium metabolism.

Absorptiometry, Photon↗
PubMed1995

Localized proton magnetic resonance spectroscopy of the brain differentiates the inborn metabolic encephalopathies in children.

Localized brain proton magnetic resonance spectroscopy (MRS) has been performed using a STEAM (stimulated echo-acquisition mode) method with a short-echo time (20 ms) in 10 children suffering from different lysosomal diseases, 6 boys with X-linked adrenoleukodystrophy (X-ALD) and 5 healthy children. Metabolic data from localized spectra were processed by principal component analysis (PCA) of 7 metabolic variables recorded on the MR spectra. PCA allows to delineate different clusters corresponding to the 2 pathological groups which are separated from each other and from the control group. The position of each spectrum on the patient map correlates with the clinical data and to the evolution of the patients subjected to a follow-up. These results also confirm the metabolic features characterizing the pathologies of the lysosome (increase in inositol) and the peroxisome (increase in choline and free lipids). PCA constitutes an alternative to the classical statistical methods to analyze and compare metabolic modifications in small populations of patients and allows to identify the most critical parameters defining the organization of the pathological populations. This analysis clearly increases the discrimination among pathologies based on the metabolic profiles obtained by MRS.

Adolescent↗
PubMed1994

What might be the impact on neurology of the analysis of brain metabolism by in vivo magnetic resonance spectroscopy?

In vivo nuclear magnetic resonance spectroscopy (MRS) of the human brain is a recently developed technique which allows to assay noninvasively in vivo key molecules of brain metabolism. After a review of the origin of the signals detected by phosphorus and proton MRS of human brain, the impact of MRS on clinical neurology is examined. MRS of the brain does not purport to be a metabolic "biopsy", but unique applications for brain MRS are (1) quantitating the oxidative state of the brain and defining neuronal death, (2) assessing and mapping neuron damage, (3) evaluating membrane alterations, and (4) characterizing encephalopathies. In the near future brain MRS will be performed routinely after conventional MRI, as a valuable metabolic (and functional) complement to the anatomical evaluation of cerebral pathologies, particularly the toxic, metabolic and infectious encephalopathies.

Brain↗
PubMed1994

Rapid evaluation of ethanol content and metabolism in human plasma using quantitative proton magnetic resonance spectroscopy.

Proton magnetic resonance spectroscopy (MRS) was used to assay ethanol in plasma. Ethanol concentrations determined by MRS and conventional enzymatic methods are in excellent agreement. In addition to ethanol, acetone, acetate and beta-hydroxybutyrate can be quantified simultaneously in the same sample. Proton MRS of plasma offers a rapid evaluation of human ethanol metabolism and may be useful in screening for chronic alcoholism.

3-Hydroxybutyric Acid↗
PubMed1994

[Marchiafava-Bignami disease: interhemispheric disconnection, Balint syndrome, spontaneously favourable outcome].

We report a new case of Marchiafava-Bignami disease with favourable outcome. This case is particular on several scores. The interhemispheric disconnection syndrome was associated with Balint's syndrome, and this had apparently never been reported in this context previously. Despite the intensity and diffusion of white matter lesions in both hemispheres, and in the absence of vitamin treatment, the clinical and neuroradiological (CT, MRI) improvement occurred early and rapidly. This course, similar to that of toxic drug withdrawal, suggested that this was not a process of vitamin deficiency. Data from the literature indicate that a wide extension of corpus callosum lesions to the semi-ovale centre has a poor vital and functional prognosis. Our case shows that this is not always correct and that the appearance of intralesional necrosis and cavitation is not the rule. We consider that the most reliable factor of poor prognosis seems to be an initial coma.

Adult↗
PubMed1994

Localized brain proton MRS metabolic patterns in HIV-related encephalopathies.

We have examined 9 healthy volunteers and 63 HIV-patients (16 asymptomatic patients and 47 patients with clinical AIDS-dementia complex, ADC) by magnetic resonance spectroscopy (MRS) and imaging (MRI) on a Siemens Magnetom SP63 (1.5 T). Proton MRS of the brain was performed at 63 MHz using the PRESS sequence (echo time = 135 ms, TR = 1.6 s). Four main results have been found: (1) HIV-related encephalopathy induces significant modifications of brain metabolism analyzed by MRS and the most sensitive metabolic parameter is the N-acetyl-aspartate/Choline ratio, (2) the correlation between MRS and MRI is good in 75% of patients, (3) in 4 of the 16 neuro-asymptomatic patients (i.e. 25%) a metabolic encephalopathy was found while MRI was still normal, and (4) MR spectra describe 3 different pathological metabolic patterns in the brain of HIV patients. Two patterns might correspond to the two entities of HIV-induced lesions i.e. HIV encephalitis and HIV-related progressive leukoencephalopathy.

AIDS Dementia Complex↗
PubMed1993

CSF and serum metabolic profile of patients with Huntington's chorea: a study by high resolution proton NMR spectroscopy and HPLC.

We studied both cerebrospinal fluid (CSF) and serum of 11 patients suffering from Huntington's disease (HD) and 12 control subjects by combining high resolution proton NMR spectroscopy and HPLC. NMR spectroscopy analysis of the CSF shows a significant increase (60%) in pyruvate concentration in HD patients. No unexpected molecules were detected. Glutamate, glutamine, aspartate, proline and GABA levels were found unchanged in the CSF of HD patients, using HPLC analysis. Conversely, a significant increase (30%) in the CSF level of glycine was detected. These observations are in agreement with the metabolic hypothesis of HD physiopathogenesis. In addition, the protocol combining NMR spectroscopy and HPLC provides a straightforward evaluation of brain metabolic status and blood-brain-barrier function.

Amino Acids↗
PubMed1993

Specific in vitro labeling of cells with a fluorine-19 probe encapsulated in antibody-targeted liposomes: a F-19 NMR spectroscopy study.

Liposomes containing dexamethasone phosphate (DMp) were covalently coupled to protein A and then incubated with murine L929 fibroblast and RDM4 thymoma cells in the presence of monoclonal antibodies specific for the major histocompatibility complex. The detection of the specific F-19 labeling of cells is rapid (minutes). Such a strategy might be useful to study the kinetics of internalization processes of bound liposomes on cultured living cells.

Animals↗