Attitude towards personal protective equipment in the French nuclear fuel industry.

This descriptive cross-sectional study examines the compliance of workers from the European Gaseous Diffusion Uranium Enrichment Consortium (EURODIF) with personal protection equipment (PPE) in view of the various hazards in the nuclear fuel industry. The PPE inventory was drawn up by an industrial hygienist in charge of the PPE at EURODIF. Two hundred and twenty seven (10%) randomly selected, active and retired, EURODIF workers filled in a questionnaire on their attitudes towards PPE.

Gadolinium-enhanced small-animal TOF magnetic resonance angiography.

So far, magnetic resonance angiography (MRA) of rodents has only been performed by using time-of-flight (TOF) MRI techniques. This is because applications of first-passage contrast agents as in humans are hampered by pronounced physiologic differences (blood volume and heart beat rate). Here we describe the use of low-dose Gd-DOTA to enhance the performance of TOF MRA in rat brain.

Inhibition of FGF receptor activity in glioma implanted into the mouse brain using the tetracyclin-regulated expression system.

We have investigated growth and vascularization of malignant glioma in mice upon conditional inhibition of fibroblast growth factor (FGF) receptor activity. C6 rat glioma cells were transfected with a dominant-negative fibroblast growth factor receptor-2 (FGFR2-DN) cDNA under the control of a tetracycline-regulated expression promoter (tet off) and implanted in the brain of immunodeficient mice. Magnetic resonance imaging analysis showed a significant decrease in tumor growth 14 days after implantation when FGFR2-DN was expressed compared to control.

Some processes of energy saving and expenditure occurring during ethanol perfusion in the isolated liver of fed rats; a Nuclear Magnetic Resonance study.

Background: In the isolated liver of fed rats, a 10 mM ethanol perfusion rapidly induced a rapid 25% decrease in the total ATP content, the new steady state resulting from both synthesis and consumption. The in situ rate of mitochondrial ATP synthesis without activation of the respiration was increased by 27%, implying an increased energy demand. An attempt to identify the ethanol-induced ATP-consuming pathways was performed using 31P and 13C Nuclear Magnetic Resonance.

Involvement of brain lactate in neuronal metabolism.

The involvement of brain lactate in neuronal metabolism was analyzed by ex vivo NMR spectroscopy with rats under the effects of pentobarbital, alphachloralose or morphine, which were infused with a solution of either [1-(13)C]glucose+lactate or glucose+[3-(13)C]lactate for 20 min. Electroencephalogram recordings indicated different brain electrical activity levels under the three drugs with a clear distinction between pentobarbital, on the one hand, and alphachloralose and morphine on the other. Labeling of metabolites in brain perchloric acid extracts and of blood glucose and lactate was determined by (13)C- and/or (1)H-observed/(13)C-edited-NMR spectroscopy.

Magnetization recovery for signal enhancement: a fast imaging DEFT-based technique.

This paper describes the development and application of a new fast MRI technique based on the DEFT principle. The sequence named MAgnetization RecoverY for Signal Enhancement (MARYSE) is composed of two completely symmetric gradient echoes separated by a 180 degrees refocusing pulse. The RF pulse scheme, 90 degrees x-180 degrees y-90 degrees -x enables restoration of the transverse magnetization along the longitudinal axis, and consequently artificially increases R1 relaxation rate.

Lactate involvement in neuron-glia metabolic interaction: (13)C-NMR spectroscopy contribution.

Glucose is commonly admitted to be the main substrate for brain energy requirement. However, it has been recently proposed that lactate, generated from glucose via glycolysis, would be the oxidative substrate for neurons, particularly during neuronal activation, according to a mechanism called the astrocyte-neuron lactate shuttle hypothesis (ANLSH). In that mechanism, glutamate released in the synaptic cleft during brain activation is taken up by astrocytes.

Lactate is a preferential oxidative energy substrate over glucose for neurons in culture.

The authors investigated concomitant lactate and glucose metabolism in primary neuronal cultures using 13C- and 1H-NMR spectroscopy. Neurons were incubated in a medium containing either [1-13C]glucose and different unlabeled lactate concentrations, or unlabeled glucose and different [3-13C]lactate concentrations. Overall, 13C-NMR spectra of cellular extracts showed that more 13C was incorporated into glutamate when lactate was the enriched substrate.

ATP generation in the Trypanosoma brucei procyclic form: cytosolic substrate level is essential, but not oxidative phosphorylation.

Trypanosoma brucei is a parasitic protist responsible for sleeping sickness in humans. The procyclic form of this parasite, transmitted by tsetse flies, is considered to be dependent on oxidative phosphorylation for ATP production. Indeed, its respiration was 55% inhibited by oligomycin, which is the most specific inhibitor of the mitochondrial F0/F1-ATP synthase.

Image-guided control of transgene expression based on local hyperthermia.

Spatial and temporal control of transgene expression is one of the major prerequisites of efficient gene therapy. Recently, a noninvasive, physical approach has been presented based on local heat in combination with a heat-sensitive promoter. This strategy requires tight temperature control in vivo.

Spatial and temporal control of transgene expression in vivo using a heat-sensitive promoter and MRI-guided focused ultrasound.

Background: Among the techniques used to induce and control gene expression, a non-invasive, physical approach based on local heat in combination with a heat-sensitive promoter represents a promising alternative but requires accurate temperature control in vivo. MRI-guided focused ultrasound (MRI-FUS) with real-time feedback control allows automatic execution of a predefined temperature-time trajectory. The purpose of this study was to demonstrate temporal and spatial control of transgene expression based on a well-defined local hyperthermia generated by MRI-FUS.

Detection of acoustic waves by NMR using a radiofrequency field gradient.

A B(1) field gradient-based method previously described for the detection of mechanical vibrations has been applied to detect oscillatory motions in condensed matter originated from acoustic waves. A ladder-shaped coil generating a quasi-constant RF-field gradient was associated with a motion-encoding NMR sequence consisting in a repetitive binomial 13;31; RF pulse train (stroboscopic acquisition). The NMR response of a gel phantom subject to acoustic wave excitation in the 20-200 Hz range was investigated.

Subacute systemic 3-nitropropionic acid intoxication induces a distinct motor disorder in adult C57Bl/6 mice: behavioural and histopathological characterisation.

Data on motor behavioural disorders induced by systemic 3-nitropropionic acid, an irreversible inhibitor of mitochondrial succinate dehydrogenase and their histopathological correlates in mice, are sparse. We thus further characterised the subacute 3-nitropropionic-acid-induced motor disorder and its time course in C57Bl/6 mice using standard behavioural tests, histopathological correlates and in vivo magnetic resonance imaging. Firstly, we studied two intoxication paradigms (340 and 560 mg 3-nitropropionic acid/kg, 7 days) compared to controls.

Top down analysis ceramide-induced mitochondrial dysfunctions: role of mitochondrial swelling.

Mitochondrial role in ceramide-induced apoptosis pathway remains unclear. Direct effects of ceramide on mitochondria (cytochrome c release, respiratory chain inhibition, oxygen radicals production..

Sugar-Starvation-Induced Changes of Carbon Metabolism in Excised Maize Root Tips.

Excised maize (Zea mays L.) root tips were used to study the early metabolic effects of glucose (Glc) starvation. Root tips were prelabeled with [1-13C]Glc so that carbohydrates and metabolic intermediates were close to steady-state labeling, but lipids and proteins were scarcely labeled.

Succinate secreted by Trypanosoma brucei is produced by a novel and unique glycosomal enzyme, NADH-dependent fumarate reductase.

In all trypanosomatids, including Trypanosoma brucei, glycolysis takes place in peroxisome-like organelles called glycosomes. These are closed compartments wherein the energy and redox (NAD(+)/NADH) balances need to be maintained. We have characterized a T.

Time-dependence of the contribution of pyruvate carboxylase versus pyruvate dehydrogenase to rat brain glutamine labelling from [1-(13) C]glucose metabolism.

[1-(13) C]glucose metabolism in the rat brain was investigated after intravenous infusion of the labelled substrate. Incorporation of the label into metabolites was analysed by NMR spectroscopy as a function of the infusion time: 10, 20, 30 or 60 min. Specific enrichments in purified mono- and dicarboxylic amino acids were determined from (1) H-observed/(13) C-edited and (13) C-NMR spectroscopy.

Effect of creatine supplementation on phosphocreatine resynthesis, inorganic phosphate accumulation and pH during intermittent maximal exercise.

In this study, we examined the effect of creatine ingestion on muscle power output, muscle phosphocreatine resynthesis, inorganic phosphate and pH during repeated brief bouts of maximal exercise. Nine healthy males performed maximal plantar flexion before and after creatine ingestion (20 g x day(-1) for 6 days). The experimental protocol consisted of five 8 s bouts (bouts 1-5) interspersed with 30 s recovery, followed by bouts 6 (8 s) and 7 (16 s) separated by 1 and 2 min, respectively.

Ethanol perfusion increases the yield of oxidative phosphorylation in isolated liver of fed rats.

The question arises as to the effect of ethanol on the actual yield of oxidative phosphorylation in the whole liver because of contradictory results reported in isolated hepatic mitochondria. The adenosine triphosphate (ATP) content of liver isolated from fed rats and perfused in the presence (10 mM) and absence of ethanol was continuously evaluated using 31P Nuclear Magnetic Resonance (NMR). An accurate estimation of mitochondrial ATP synthesis in the whole organ was obtained by subtracting the glycolytic ATP supply from the total ATP production.

MR detection of mechanical vibrations using a radiofrequency field gradient.

A new method for NMR characterization of mechanical waves, based upon radiofrequency field gradient for motion encoding, is proposed. A binomial B1 gradient excitation scheme was used to visualize the mobile spins undergoing a periodic transverse mechanical excitation. A simple model was designed to simulate the NMR signal as a function of the wave frequency excitation and the periodicity of the NMR pulse sequence.

Effect of exogenous lactate on rat glioma metabolism.

Glioma-bearing rats were infused intravenously with a solution containing either [3-(13)C]lactate or both glucose and [3-(13)C]lactate for 20 min or 1 hr. Perchloric acid extracts of healthy and tumoral brain tissues were prepared and analyzed by (13)C- and (1)H-observed (13)C-edited nuclear magnetic resonance (NMR) spectroscopy to determine (13)C-label incorporation into brain tissue and glioma metabolites. Moreover, (13)C enrichments in blood lactate and glucose were determined from (1)H-NMR spectra.

Butyrate impairs energy metabolism in isolated perfused liver of fed rats.

This study was designed to test the effects of short-chain fatty acids (SCFA) with an even number of carbon atoms on hepatic energy metabolism. The effect of the SCFA was evaluated by measuring liver ATP content and oxygen consumption. The ATP content was evaluated using (31)P nuclear magnetic resonance in isolated liver from fed rats.

Functional and metabolic early changes in calf muscle occurring during nutritional repletion in malnourished elderly patients.

Background: Metabolic alterations in skeletal muscle associated with malnutrition and the potential reversibility of such alterations during refeeding are not fully understood.

Objective: We characterized early changes in muscle during refeeding in malnourished, hospitalized elderly subjects.

Design: Muscle function, metabolism, and mass were evaluated in 24 clinically stable patients (11 were malnourished) by using isokinetic plantar flexor torque measurements and nuclear magnetic resonance (NMR) imaging for medial gastrocnemius mass assessment and 31P and 13C NMR spectroscopy for inorganic phosphate (Pi), phosphocreatine, and glycogen quantitation.

Metabolism of [1-(13)C)glucose and [2-(13)C]acetate in the hypoxic rat brain.

The effects of hypoxia on the metabolism of the central nervous system were investigated in rats submitted to a low oxygen atmosphere (8% O(2); 92% N(2)). [1-(13)C]glucose and [2-(13)C]acetate were used as substrates, this latter being preferentially metabolized by glial cells. After 1-h substrate infusion, the incorporation of 13C in brain metabolites was determined by NMR spectroscopy.