Deep hypothermia and rewarming alters glutamate levels and glycogen content in cultured astrocytes.

BACKGROUND: Deep hypothermia has been associated with an increased incidence of postoperative neurologic dysfunction after cardiac surgery in children. Recent studies suggest an excitotoxic mechanism involving overstimulation of glutamate receptors. Extracellular glutamate uptake occurs primarily by astrocytes. Astrocytes also store glycogen, which may be used to sustain the energy-consuming glutamate uptake. Extracellular glutamate and glycogen content were studied during temperature changes mimicking cardiopulmonary bypass in vivo. METHODS: Primary cultures of cerebral cortical astrocytes were used in a specially designed incubator allowing continuous changes of temperature and ambient gas concentrations. The sequence of events was as follows: normothermia, rapid cooling (2.8 degrees C/min) followed by 60 min of deep hypothermia (15 degrees C), followed by rewarming (3.0 degrees C/min) and subsequent 5 h of mild hyperthermia (38.5 degrees C). Two different conditions of oxygenation were studied: (1) normoxia (25% O2, 70% N2, 5% CO2); or (2) hyperoxia (95% O2, 5% CO2). The extracellular glutamate concentrations and intracellular glycogen levels were measured at nine time points. RESULTS: One hundred sixty-two cultures were studied in four independent experiments. The extracellular concentration of glutamate in the normoxic group increased significantly from 35+/-10 nM/mg protein at baseline up to 100+/-15 nM/mg protein at the end of 5 h of mild hyperthermia (P < 0.05). In contrast, extracellular glutamate levels did not vary from control in the hyperoxic group. Glycogen levels decreased significantly from 260+/-85 nM/mg protein at baseline to < 25+/-5 nM/mg protein at the end of 5 h in the normoxic group (P < 0.05) but returned to control levels after rewarming in the hyperoxic group. No morphologic changes were observed in either group. CONCLUSION: The extracellular concentration of glutamate increases, whereas the intracellular glycogen content decreases when astrocytes are exposed to a sequence of deep hypothermia and rewarming. This effect of hypothermia is prevented when astrocytes are exposed to hyperoxic conditions.

Skeletal muscle mitochondrial and lipid droplet content assessed with standardized grid sizes for stereology.

Skeletal muscle mitochondrial (Mito) and lipid droplet (Lipid) content are often measured in human translational studies. Stereological point counting allows computing Mito and Lipid volume density (Vd) from micrographs taken with transmission electron microscopes. Former studies are not specific as to the size of individual squares that make up the grids, making reproducibility difficult, particularly when different magnifications are used. Our objective was to determine which size grid would be best at predicting fractional volume efficiently without sacrificing reliability and to test a novel method to reduce sampling bias. Methods: ten subjects underwent vastus lateralis biopsies. Samples were fixed, embedded, and cut longitudinally in ultrathin sections of 60 nm. Twenty micrographs from the intramyofibrillar region were taken per subject at Ã-33,000 magnification. Different grid sizes were superimposed on each micrograph: 1,000 Ã- 1,000 nm, 500 Ã- 500 nm, and 250 Ã- 250 nm. Results: mean Mito and Lipid Vd were not statistically different across grids. Variability was greater when going from 1,000 Ã- 1,000 to 500 Ã- 500 nm grid than from 500 Ã- 500 to 250 Ã- 250 nm grid. Discussion: this study is the first to attempt to standardize grid size while keeping with the conventional stereology principles. This is all in hopes of producing replicable assessments that can be obtained universally across different studies looking at human skeletal muscle mitochondrial and lipid droplet content.

3-year follow-up results of bone mineral content and density after a school-based physical activity randomized intervention trial.

BACKGROUND: As an important modifiable lifestyle factor in osteoporosis prevention, physical activity has been shown to positively influence bone mass accrual during growth. We have previously shown that a nine month general school based physical activity intervention increased bone mineral content (BMC) and density (aBMD) in primary school children. From a public health perspective, a major key issue is whether these effects persist during adolescence. We therefore measured BMC and aBMD three years after cessation of the intervention to investigate whether the beneficial short-term effects persisted. METHODS: All children from 28 randomly selected first and fifth grade classes (intervention group (INT): 16 classes, n=297; control group (CON): 12 classes, n=205) who had participated in KISS (Kinder-und Jugendsportstudie) were contacted three years after cessation of the intervention program. The intervention included daily physical education with daily impact loading activities over nine months. Measurements included anthropometry, vigorous physical activity (VPA) by accelerometers, and BMC/aBMD for total body, femoral neck, total hip, and lumbar spine by dual-energy X-ray absorptiometry (DXA). Sex- and age-adjusted Z-scores of BMC or aBMD at follow-up were regressed on intervention (1 vs. 0), the respective Z-score at baseline, gender, follow-up height and weight, pubertal stage at follow-up, previous and current VPA, adjusting for clustering within schools. RESULTS: 377 of 502 (75%) children participated in baseline DXA measurements and of those, 214 (57%) participated to follow-up. At follow-up INT showed significantly higher Z-scores of BMC at total body (adjusted group difference: 0.157 units (0.031-0.283); p=0.015), femoral neck (0.205 (0.007-0.402); p=0.042) and at total hip (0.195 (0.036 to 0.353); p=0.016) and higher Z-scores of aBMD for total body (0.167 (0.016 to 0.317); p=0.030) compared to CON, representing 6-8% higher values for children in the INT. No differences could be found for the remaining bone parameters. For the subpopulation with baseline VPA (n=163), effect sizes became stronger after baseline VPA adjustment. After adjustment for baseline and current VPA (n=101), intervention effects were no longer significant, while effect sizes remained the same as without adjustment for VPA. CONCLUSION: Beneficial effects on BMC of a nine month general physical activity intervention appeared to persist over three years. Part of the maintained effects may be explained by current physical activity.

Long-term and long range migration of radioisotopes in terrestrial systems : mechanisms of radioisotopes (Cs, Sr, Pu, Am) mobilization in soils

Summary Artificial radionuclides were released in the environment during the atmospheric nuclear weapon tests and after accidental events involving nuclear industries. As a primary receptor of the deposition, the soil is a very sensitive compartment and understanding the interaction and migration of radionuclides within soils allows the development of scenario for the contamination risk of the population and of the environment. Most available field studies on radionuclides in soils only concern one or two isotopes, mostly 137Cs, and few physico-chemical soil parameters. The purpose of this study was a broader understanding of the radioecology of an Alpine valley. In a first part, we aimed to describe the depth distribution of 137Cs, 90Sr, 239+240Pu, and 241Am within different alpine soils and to identify some stable elements as indicators for accumulating layers. In the central part of the study, the goal was to investigate the repartition of ^Sr and 239Pu between the truly dissolved fraction and the colloidal fraction of the soil solutions and to identify the nature of colloids involved in the adsorption of ^Sr and 239Pu. These results were integrated in an "advection- sorption" transport model seeking to explain the migration of 239Pu and 90Sr within the soils and to assess the importance of colloidal transport for these two isotopes. A further aspect studied was the role of the competition between the radioisotopes (137Cs and 90Sr) and their stable chemical analogues (K and Ca) with respect to plant uptake by different plant species. The results on the depth distribution within the soils showed that 137Cs was mostly retained in the topsoil, to the exception of an organic-rich soil (Histosol 2) receiving important surface runoff, where migration down to a depth of 30 cm was observed. 137Cs depth distribution within the soils was similar to unsupported 210Pb depth distribution. The plant uptake of 137Cs clearly depended on the concentration of exchangeable potassium in the soils. Moreover, we showed that the 137Cs uptake by certain species of the taxonomic orders Poales and Rosales was more sensitive to the increase in exchangeable Κ compared to other orders. Strontium-90 was much more mobile in the soils than 137Cs and depth migration and accumulation in specific AI- and Fe-rich layers were found down to 30 cm. Copper and Ni showed accumulations in these same layers, indicating their potential to be used as indicators for the migration of ^Sr within the soils. In addition, we observed a 90Sr activity peak in the topsoil that can be attributable to recycling of 90Sr by plant uptake. We demonstrated for the first time that a part of 90Sr (at least 40%) was associated with the colloids in organic-rich soil solutions. Therefore, we predict a significant effect of the colloidal migration of ^Sr in organic-rich soil solutions. The plant uptake results for 90Sr indicated a phylogenetic effect between Non-Eudicot and Eudicots: the order Poales concentrating much less 90Sr than Eudicots do. Moreover, we were able to demonstrate that the sensitivity of the 90Sr uptake by 5 different Alpine plant species to the amount of exchangeable Ca was species-independent. Plutonium and 241Am accumulated in the second layer of all soils and only a slight migration deeper than 20 cm was observed. Plutonium and 241Am showed a similar depth distribution in the soils. The model results suggested that the present day migration of 239Pu was very slow and that the uptake by plants was negligible. 239Pu activities between 0.01 to 0.08 mBq/L were measured in the bulk soil solutions. Migration of 239Pu with the soil solution is dominated by colloidal transport. We reported strong evidences that humic substances were responsible of the sorption of 239Pu to the colloidal fraction of the soil solutions. This was reflected by the strong correlation between 239Pu concentrations and the content of (colloidal) organic matter in the soil solution. Résumé Certains radioéléments artificiels ont été disséminés dans l'environnement suite aux essais atmosphériques de bombes nucléaires et suite à des accidents impliquant les industries nucléaires. En tant que récepteur primaire de la déposition, le sol est un compartiment sensible et des connaissances sur les interactions et la migration des radioéléments dans le sol permettent de développer des modèles pour estimer la contamination de la population et de l'environnement. Actuellement, la plupart des études de terrain sur ce sujet concernent uniquement un ou deux radioéléments, surtout le 137Cs et peu d'études intègrent les paramètres du sol pour expliquer la migration des radioéléments. Le but général de cette étude était une compréhension étendue de la radio-écologie d'une vallée alpine. Notre premier objectif était de décrire la distribution en profondeur de 137Cs, ^Sr, 239+240pu et 241Am dans différents sols alpins en relation avec des éléments stables du sol, dans le but d'identifier des éléments stables qui pourraient servir d'indicateurs pour des horizons accumulateurs. L'objectif de la deuxième partie, qui était la partie centrale de l'étude, était d'estimer le pourcentage d'activité sous forme colloïdale du 239Pu et du 90Sr dans les solutions des sols. De plus nous avons déterminé la nature des colloïdes impliqués dans la fixation du ^Sr et 239Pu. Nous avons ensuite intégré ces résultats dans un modèle de transport développé dans le but de décrire la migration du 239Pu et 90Sr dans le sol. Finalement, nous avons étudié l'absorption de 137Cs et 90Sr par les plantes en fonction de l'espèce et de la compétition avec leur élément analogue stable (K et Ca). Les résultats sur la migration en profondeur du 137Cs ont montré que ce radioélément était généralement retenu en surface, à l'exception d'un sol riche en matière organique dans lequel nous avons observé une nette migration en profondeur. Dans tous les sols, la distribution en profondeur du 137Cs était corrélée avec la distribution du 210Pb. L'absorption du 137Cs par les plantes, était dépendante de la concentration en Κ échangeable dans le sol, le potassium étant un compétiteur. De plus, nous avons observé que les espèces ne réagissaient pas de la même manière aux variations de la concentration de Κ échangeable. En effet, les espèces appartenant aux ordres des Poales et des Rosales étaient plus sensibles aux variations de potassium échangeable dans le sol. Dans tous les sols Le 90Sr était beaucoup plus mobile que le 137Cs. En effet, nous avons observé des accumulations de 90Sr dans des horizons riches en Fe et Al jusqu'à 30 cm de profondeur. De plus, le Cu et le Ni montraient des accumulations dans les mêmes horizons que le 90Sr, indiquant qu'il pourrait être possible d'utiliser ces deux éléments comme analogues pour la migration du 90Sr. D'après le modèle développé, le pic de 90Sr dans les premiers centimètres du sol peut être attribué à du recyclage par les plantes. Le 90Sr en solution était principalement sous forme dissoute dans des solutions de sols peu organique (entre 60 et 100% de 90Sr dissous). Par contre, dans des solutions organiques, un important pourcentage de 90Sr (plus de 40%) était associé aux colloïdes. La migration colloïdale du 90Sr peut donc être significative dans des solutions organiques. Comme pour le 137Cs, l'absorption du 90Sr par les plantes dépendait de la concentration de son analogue chimique dans la fraction échangeable du sol. Par contre, les espèces de plantes étudiées avaient la même sensibilité aux variations de la concentration du calcium échangeable. Le plutonium et l'américium étaient accumulés dans le deuxième horizon du sol et nous avons observé seulement une faible migration plus profondément que 20 cm. Selon le modèle, la migration actuelle du plutonium est très lente et l'absorption par les plantes semble négligeable. Nous avons mesuré entre 0.01 et 0.08 mBq/L de 239Pu dans les solutions de sol brutes. La migration du plutonium par la solution du sol est due principalement aux colloïdes, probablement de nature humique. Résumé grand public Dans les années 1950 à 1960, l'environnement a été contaminé par des éléments radioactifs (radioéléments) artificiels provenant des essais des armes atomiques et de l'industrie nucléaire. En effet, durant ces années, les premiers essais de bombes atomiques se faisaient dans l'atmosphère, libérant de grandes quantités d'éléments radioactifs. De plus certains accidents impliquant l'industrie nucléaire civile ont contribué à la dissémination d'éléments radioactifs dans l'environnement. Ce fut par exemple le cas de l'accident de la centrale atomique de Tchernobyl en 1986 qui a causé une importante contamination d'une grande partie de l'Europe par le 137Cs. Lorsqu'ils sont libérés dans l'atmosphère, les radioéléments sont dispersés et transportés par les courants atmosphériques, puis peuvent être déposés dans l'environnement, principalement par les précipitations. Une fois déposés sur le sol, les radioéléments vont interagir avec les composants du sol et migrer plus ou moins vite. La connaissance des interactions des éléments radioactifs avec le sol est donc importante pour prédire les risques de contamination de l'environnement et de l'homme. Le but général de ce travail était d'évaluer la migration de différents éléments radioactifs (césium-137, strontium-90, plutonium et américium-241) à travers le sol. Nous avons choisi un site d'étude en milieu alpin (Val Piora, Tessin, Suisse), contaminé en radioéléments principalement par les retombées de l'accident de Tchernobyl et des essais atmosphériques de bombes atomiques. Dans un premier temps, nous avons caractérisé la distribution en profondeur des éléments radioactifs dans le sol et l'avons comparée à divers éléments stables. Cette comparaison nous a permit de remarquer que le cuivre et le nickel s'accumulaient dans les mêmes horizons du sol que le strontium-90 et pourraient donc être utilisés comme analogue pour la migration du strontium-90 dans les sols. Dans la plupart des sols étudiés, la migration du césium-137, du plutonium et de l'américium-241 était lente et ces radioéléments étaient donc accumulés dans les premiers centimètres du sol. Par contre, le strontium-90 a migré beaucoup plus rapidement que les autres radioéléments si bien qu'on observe des accumulations de strontium-90 à plus de 30 cm de profondeur. Les radioéléments migrent dans la solution du sol soit sous forme dissoute, soit sous forme colloïdale, c'est-à-dire associés à des particules de diamètre < Ιμηι. Cette association avec des colloïdes permet à des radioéléments peu solubles, comme le plutonium, de migrer plus rapidement qu'attendu. Nous avons voulu savoir quelle était la part de strontium-90 et plutonium associés à des colloïdes dans la solution du sol. Les résultats ont montré que le plutonium en solution était principalement associé à des colloïdes de type organique. Quant au strontium-90, ce dernier était en partie associé à des colloïdes dans des solutions de sol riches en matière organique, par contre, il était principalement sous forme dissoute dans les solutions de sol peu organiques. L'absorption de radioéléments par les plantes représente une voie importante pour le transfert vers la chaîne alimentaire, par conséquent pour la contamination de l'homme. Nous avons donc étudié le transfert du césium-137 et du strontium-90 de plusieurs sols vers différentes espèces de plantes. Les résultats ont montré que l'absorption des radioéléments par les plantes était liée à la concentration de leur analogue chimique (calcium pour le strontium-90 et potassium pour le césium- 137) dans la fraction échangeable du sol. De plus certaines espèces de plantes accumulent significativement moins de strontium-90.

Tuning In to Sound: Frequency-Selective Attentional Filter in Human Primary Auditory Cortex.

Cocktail parties, busy streets, and other noisy environments pose a difficult challenge to the auditory system: how to focus attention on selected sounds while ignoring others? Neurons of primary auditory cortex, many of which are sharply tuned to sound frequency, could help solve this problem by filtering selected sound information based on frequency-content. To investigate whether this occurs, we used high-resolution fMRI at 7 tesla to map the fine-scale frequency-tuning (1.5 mm isotropic resolution) of primary auditory areas A1 and R in six human participants. Then, in a selective attention experiment, participants heard low (250 Hz)- and high (4000 Hz)-frequency streams of tones presented at the same time (dual-stream) and were instructed to focus attention onto one stream versus the other, switching back and forth every 30 s. Attention to low-frequency tones enhanced neural responses within low-frequency-tuned voxels relative to high, and when attention switched the pattern quickly reversed. Thus, like a radio, human primary auditory cortex is able to tune into attended frequency channels and can switch channels on demand.

Deoxyribonucleic acid content as an indicator of progression of squamous cell carcinogenesis in the esophagus: comparative analysis on imprint-cytospin and tissue section preparation.

BACKGROUND: The purpose of this study was to explore the potential use of image analysis on tissue sections preparation as a predictive marker of early malignant changes during squamous cell (SC) carcinogenesis in the esophagus. Results of DNA ploidy quantification on formalin-fixed, paraffin-embedded tissue using two different techniques were compared: imprint-cytospin and 6 microm thick tissue sections preparation. METHODS: This retrospective study included 26 surgical specimens of squamous cell carcinoma (SCC) from patients who underwent surgery alone at the Department of Surgery in CHUV Hospital in Lausanne between January 1993 and December 2000. We analyzed 53 samples of healthy tissue, 43 tumors and 7 lymph node metastases. RESULTS: Diploid DNA histogram patterns were observed in all histologically healthy tissues, either distant or proximal to the lesion. Aneuploidy was observed in 34 (79%) of 43 carcinomas, namely 24 (75%) of 32 early squamous cell carcinomas and 10 (91%) of 11 advanced carcinomas. DNA content was similar in the different tumor stages, whether patients presented with single or multiple synchronous tumors. All lymph node metastases had similar DNA content as their primary tumor. CONCLUSIONS: Early malignant changes in the esophagus are associated with alteration in DNA content, and aneuploidy tends to correlate with progression of invasive SCC. A very good correlation between imprint-cytospin and tissue section analysis was observed. Although each method used here showed advantages and disadvantages; tissue sections preparation provided useful information on aberrant cell-cycle regulation and helped select the optimal treatment for the individual patient along with consideration of other clinical parameters.

Exposure to radio-frequency electromagnetic fields from broadcast transmitters and risk of childhood cancer: a census-based cohort study.

We investigated the association between exposure to radio-frequency electromagnetic fields (RF-EMFs) from broadcast transmitters and childhood cancer. First, we conducted a time-to-event analysis including children under age 16 years living in Switzerland on December 5, 2000. Follow-up lasted until December 31, 2008. Second, all children living in Switzerland for some time between 1985 and 2008 were included in an incidence density cohort. RF-EMF exposure from broadcast transmitters was modeled. Based on 997 cancer cases, adjusted hazard ratios in the time-to-event analysis for the highest exposure category (>0.2 V/m) as compared with the reference category (<0.05 V/m) were 1.03 (95% confidence interval (CI): 0.74, 1.43) for all cancers, 0.55 (95% CI: 0.26, 1.19) for childhood leukemia, and 1.68 (95% CI: 0.98, 2.91) for childhood central nervous system (CNS) tumors. Results of the incidence density analysis, based on 4,246 cancer cases, were similar for all types of cancer and leukemia but did not indicate a CNS tumor risk (incidence rate ratio = 1.03, 95% CI: 0.73, 1.46). This large census-based cohort study did not suggest an association between predicted RF-EMF exposure from broadcasting and childhood leukemia. Results for CNS tumors were less consistent, but the most comprehensive analysis did not suggest an association.

Characterization of OsMIK in a rice mutant with reduced phytate content reveals an insertion of a rearranged retrotransposon.

The rice low phytic acid (lpa) mutant Os-lpa-XS110-1(XS-lpa) has ~45 % reduction in seed phytic acid (PA) compared with the wild-type cultivar Xiushui 110. Previously, a single recessive gene mutation was shown to be responsible for the lpa phenotype and was mapped to a region of chromosome 3 near OsMIK (LOC_Os03g52760) and OsIPK1 (LOC_Os03g51610), two genes involved in PA biosynthesis. Here, we report the identification of a large insert in the intron of OsMIK in the XS-lpa mutant. Sequencing of fragments amplified through TAIL-PCRs revealed that the insert was a derivative of the LINE retrotransposon gene LOC_Os03g56910. Further analyses revealed the following characteristics of the insert and its impacts: (1) the inserted sequence of LOC_Os03g56910 was split at its third exon and rejoined inversely, with its 5' and 3' flanking sequences inward and the split third exon segments outward; (2) the LOC_Os03g56910 remained in its original locus in XS-lpa, and the insertion probably resulted from homologous recombination repair of a DNA double strand break; (3) while the OsMIK transcripts of XS-lpa and Xiushui 110 were identical, substantial reductions of the transcript abundance (~87 %) and the protein level (~60 %) were observed in XS-lpa, probably due to increased methylation in its promoter region. The above findings are discussed in the context of plant mutagenesis, epigenetics and lpa breeding.

Myelin basic protein content of aggregating rat brain cell cultures treated with cytokines and/or demyelinating antibody: effects of macrophage enrichment.

The demyelinative potential of the cytokines interleukin-1 alpha (IL-1 alpha), interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) has been investigated in myelinating aggregate brain cell cultures. Treatment of myelinated cultures with these cytokines resulted in a reduction in myelin basic protein (MBP) content. This effect was additively increased by anti-myelin/oligodendrocyte glycoprotein (alpha-MOG) in the presence of complement. Qualitative immunocytochemistry demonstrated that peritoneal macrophages, added to the fetal telencephalon cell suspensions at the start of the culture period, successfully integrated into aggregate cultures. Supplementing the macrophage component of the cultures in this fashion resulted in increased accumulation of MBP. The effect of IFN-gamma on MBP content of cultures was not affected by the presence of macrophages in increased numbers.

French summaries of product characteristics: content in relation to therapeutic monitoring of psychotropic drugs.

The prescription information (summary of product characteristics, SPC) is compiled by the pharmaceutical industry as required by the national regulatory authorities. They vary in their content about the properties of drugs and about the usefulness of therapeutic drug monitoring (TDM) in the blood of patients. Based on a previous study carried out in Germany, the degree of agreement of French SPC for 59 psychotropic drugs with the existing medico-scientific evidence in the area of TDM was examined using a recently developed instrument. A summary score of SPC content (SPCC) related to TDM (SPCC(TDM)) has been calculated and compared with the level of recommendation of TDM of the AGNP-TDM expert group consensus guidelines for TDM in psychiatry [AGNP: Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (Association for neuropsychopharmacology and pharmacopsychiatry)]. Among the antidepressants, antipsychotics, tranquillizers/hypnotic agents and mood stabilizers, the highest SPCC(TDM) scores in the French SPC were reached for imipramine (16), haloperidol (6), clonazepam (8) and lithium (23), respectively. Results were similar to those obtained from the analysis of German SPC, and considerable disagreement was found between the information on TDM in SPC and existing medico-scientific evidence, albeit less in the case of mood stabilizers. Taking into account the recommendations of the AGNP-TDM expert group guidelines, there is a deficit in the French SPC concerning TDM-relevant information. An amelioration of this situation could help to improve the clinical practice of TDM of psychotropic drugs, as the SPC is a widely used tool.