A simple-architecture fibered transmission system for dissemination of high stability 100 MHz signals.

We report on the development of a simple-architecture fiber-based frequency distribution system used to transfer high frequency stability 100 MHz signals. This work is focused on the emitter and the receiver performances that allow the transmission of the radio-frequency signal over an optical fiber. The system exhibits a residual fractional frequency stability of 1 × 10-14 at 1 s integration time and in the low 10-16 range after 100 s. These performances are suitable to transfer the signal of frequency references such as those of a state-of-the-art hydrogen maser without any phase noise compensation scheme. As an application, we demonstrate the dissemination of such a signal through a 100 m long optical fiber without any degradation. The proposed setup could be easily extended for operating frequencies in the 10 MHz-1 GHz range.

Mitochondrial energetic and AKT status mediate metabolic effects and apoptosis of metformin in human leukemic cells.

Previous reports demonstrate that metformin, an anti-diabetic drug, can decrease the risk of cancer and inhibit cancer cell growth. However, its mechanism in cancer cells is still unknown. Metformin significantly blocks cell cycle and inhibits cell proliferation and colony formation of leukemic cells. However, the apoptotic response to metformin varies. Furthermore, daily treatment with metformin induces apoptosis and reduces tumor growth in vivo. While metformin induces early and transient activation of AMPK, inhibition of AMPKα1/2 does not abrogate anti-proliferative or pro-apoptotic effects of metformin. Metformin decreases electron transport chain complex I activity, oxygen consumption and mitochondrial ATP synthesis, while stimulating glycolysis for ATP and lactate production, pentose phosphate pathway for purine biosynthesis, fatty acid metabolism, as well as anaplerotic and mitochondrial gene expression. Importantly, leukemic cells with high basal AKT phosphorylation, glucose consumption or glycolysis exhibit a markedly reduced induction of the Pasteur effect in response to metformin and are resistant to metformin-induced apoptosis. Accordingly, glucose starvation or treatment with deoxyglucose or an AKT inhibitor induces sensitivity to metformin. Overall, metformin elicits reprogramming of intermediary metabolism leading to inhibition of cell proliferation in all leukemic cells and apoptosis only in leukemic cells responding to metformin with AKT phosphorylation and a strong Pasteur effect.

Trypanosoma cruzi: tripomastigotes en líquido pleural de un paciente con SIDA / Trypanosoma cruzi: trypomastigote forms in pleural fluid of a patient with AIDS

The presence of numerous trypomastigote forms of Trypanosoma cruzi in the pleural fluid of a patient with AIDS from Santiago del Estero, Agentina, was detected. Chagas disease is endemic in some countries of Latin America. To our knowledge, the finding of trypomastigote forms of T. cruzi in the pleural fluid has not yet been described in the literature.

Se detectó la presencia de numerosos tripomastigotes de Trypanosoma cruzi en el líquido pleural de un paciente con SIDA proveniente de Santiago del Estero, Argentina. La enfermedad de Chagas es endémica en algunos países de América Latina. Según nuestro conocimiento el hallazgo de tripomastigotes de T. cruzi en el líquido pleural no ha sido previamente descrito en la literatura médica.

Phylogeography of the red coral (Corallium rubrum): inferences on the evolutionary history of a temperate gorgonian.

The red coral Corallium rubrum (Cnidaria, Octocorallia) is an exploited, long-lived sessile species from the Mediterranean Sea and the adjacent coastline in the Atlantic Ocean. Surveys of genetic variation using microsatellites have shown that populations of C. rubrum are characterized by strong differentiation at the local scale but a study of the phylogeography of this species was still lacking. Here, we used seven polymorphic microsatellite loci, together with sequence data from an intron of the elongation factor 1 (EF1) gene, to investigate the genetic structure of C. rubrum across its geographical range in the western Mediterranean Sea and in the Adriatic Sea. The EF1 sequences were also used to analyse the consequences of demographic fluctuations linked with past environmental change. Clustering analysis with microsatellite loci highlighted three to seven genetic groups with the distinction of North African and Adriatic populations; this distinction appeared significant with AMOVA and differentiation tests. Microsatellite and EF1 data extended the isolation by distance pattern previously observed for this species at the western Mediterranean scale. EF1 sequences confirmed the genetic differentiation observed between most samples with microsatellites. A statistical parsimony network of EF1 haplotypes provided no evidence of high sequence divergence among regions, suggesting no long-term isolation. Selective neutrality tests on microsatellites and EF1 were not significant but should be interpreted with caution in the case of EF1 because of the low sample sizes for this locus. Our results suggest that recent Quaternary environmental fluctuations had a limited impact on the genetic structure of C. rubrum.

[Trypanosoma cruzi: trypomastigote forms in pleural fluid of a patient with AIDS]. / Trypanosoma cruzi: tripomastigotes en líquido pleural de un paciente con SIDA.

The presence of numerous trypomastigote forms of Trypanosoma cruzi in the pleural fluid of a patient with AIDS from Santiago del Estero, Argentina, was detected. Chagas disease is endemic in some countries of Latin America. To our knowledge, the finding of trypomastigote forms of T. cruzi in the pleural fluid has not yet been described in the literature.

Functional dynamic compartmentalization of respiratory chain intermediate substrates: implications for the control of energy production and mitochondrial diseases.

Activity defects in respiratory chain complexes are responsible for a large variety of pathological situations, including neuromuscular diseases and multisystemic disorders. Their impact on energy production is highly variable and disproportional. The same biochemical or genetic defect can lead to large differences in clinical symptoms and severity between tissues and patients, making the pathophysiological analysis of mitochondrial diseases difficult. The existence of compensatory mechanisms operating at the level of the respiratory chain might be an explanation for the biochemical complexity observed for respiratory defects. Here, we analyzed the role of cytochrome c and coenzyme Q in the attenuation of complex III and complex IV pharmacological inhibition on the respiratory flux. Spectrophotometry, HPLC-EC, polarography and enzymology permitted the calculation of molar ratios between respiratory chain components, giving values of 0.8:61:3:12:6.8 in muscle and 1:131:3:9:6.5 in liver, for CII:CoQ:CIII:Cyt c:CIV. The results demonstrate the dynamic functional compartmentalization of respiratory chain substrates, with the existence of a substrate pool that can be recruited to maintain energy production at normal levels when respiratory chain complexes are inhibited. The size of this reserve was different between muscle and liver, and in proportion to the magnitude of attenuation of each respiratory defect. Such functional compartmentalization could result from the recently observed physical compartmentalization of respiratory chain substrates. The dynamic nature of the mitochondrial network may modulate this compartmentalization and could play a new role in the control of mitochondrial respiration as well as apoptosis.

Physiological diversity of mitochondrial oxidative phosphorylation.

To investigate the physiological diversity in the regulation and control of mitochondrial oxidative phosphorylation, we determined the composition and functional features of the respiratory chain in muscle, heart, liver, kidney, and brain. First, we observed important variations in mitochondrial content and infrastructure via electron micrographs of the different tissue sections. Analyses of respiratory chain enzyme content by Western blot also showed large differences between tissues, in good correlation with the expression level of mitochondrial transcription factor A and the activity of citrate synthase. On the isolated mitochondria, we observed a conserved molar ratio between the respiratory chain complexes and a variable stoichiometry for coenzyme Q and cytochrome c, with typical values of [1-1.5]:[30-135]:[3]:[9-35]:[6.5-7.5] for complex II:coenzyme Q:complex III:cytochrome c:complex IV in the different tissues. The functional analysis revealed important differences in maximal velocities of respiratory chain complexes, with higher values in heart. However, calculation of the catalytic constants showed that brain contained the more active enzyme complexes. Hence, our study demonstrates that, in tissues, oxidative phosphorylation capacity is highly variable and diverse, as determined by different combinations of 1) the mitochondrial content, 2) the amount of respiratory chain complexes, and 3) their intrinsic activity. In all tissues, there was a large excess of enzyme capacity and intermediate substrate concentration, compared with what is required for state 3 respiration. To conclude, we submitted our data to a principal component analysis that revealed three groups of tissues: muscle and heart, brain, and liver and kidney.

Working memory deficits in adult rats after prenatal disruption of neurogenesis.

We investigated the cognitive consequences of a prenatal injection of the mitotic inhibitor methylazoxymethanol (MAM) into pregnant rats at embryonic day 15 (E15) or 17 (E17). The male offspring were tested when adult on a version of the radial-arm maze task that assesses spatial working memory with an extended delay, where performance is dependent, in part, on the hippocampal-prefrontal circuit. A major impairment of spatial learning was observed in E15 MAM rats. However, the E17 MAM rats did learn the rule but were impaired selectively in the 30-min delay-interposed task. Morphologically, the E15 MAM rats exhibited dramatic gross brain abnormalities, whereas the E17 MAM animals displayed aberrant cell migration in the hippocampus and a disrupted laminar pattern in the neocortex. These results suggest that late gestational MAM injection (E17) causes a cognitive impairment in a prefrontal cortex-hippocampus-dependent working memory task. This approach could provide a new developmental model of disorders associated with working memory deficits, such as schizophrenia.

Sarcolemma phospholipid structure investigated by immunogold electron microscopy and (31)P NMR spectroscopy with lanthanide ions.

The biological functions of plasma membranes depend greatly on the biophysical properties resulting from protein and phospholipid structure. We investigated the phospholipid structure of the normal sarcolemma membrane, which is known to be highly dysfunctional in myopathies. Combining electron microscopy and (31)P nuclear magnetic resonance (NMR) spectroscopy on isolated sarcolemma vesicles, we find that (i) the sarcolemma vesicles maintain the in-vivo cellular sidedness, (ii) the phospholipid mobility is close to that observed in model membranes (similar lateral diffusion coefficients and spin-lattice T(1) relaxation times). Using broad-band and magic angle spinning (31)P NMR spectroscopy with lanthanide ions (Pr(3+)), it is possible to quantify the distribution of phospholipids between internal and external membrane layers, showing that the trans-bilayer distribution is highly asymmetrical.

Initiation of DNA replication by DNA polymerases from primers forming a triple helix.

Despite extensive studies on oligonucleotide-forming triple helices, which were discovered in 1957, their possible relevance in the initiation of DNA replication remains unknown. Using sequences forming triple helices, we have developed a DNA polymerisation assay by using hairpin DNA templates with a 3' dideoxynucleotide end and an unpaired 5'-end extension to be replicated. The T7 DNA polymerase successfully elongated nucleotides to the expected size of the template from the primers forming triple helices composed of 9-14 deoxyguanosine-rich residues. The triple helix-forming primer required for this reaction has to be oriented parallel to the homologous sequence of the hairpin DNA template. Substitution of the deoxyguanosine residues by N7 deazadeoxyguanosines in the hairpin of the template prevented primer elongation, suggesting that the formation of a triple helix is a prerequisite for primer elongation. Furthermore, DNA sequencing could be achieved with the hairpin template through partial elongation of the third DNA strand forming primer. The T4 DNA polymerase and the Klenow fragment of DNA polymerase I provided similar DNA elongation to the T7 polymerase-thioredoxin complex. On the basis of published crystallographic data, we show that the third DNA strand primer fits within the catalytic centre of the T7 DNA polymerase, thus underlying this new property of several DNA polymerases which may be relevant to genome rearrangements and to the evolution of the genetic apparatus, namely the DNA structure and replication processes.

Effects of repeated systemic administration of d-Fenfluramine on serotonin and glutamate release in rat ventral hippocampus: comparison with methamphetamine using in vivo microdialysis.

We compared the effects of three systemic injections of various doses of d-Fenfluramine, an indirect serotonergic agonist (1.3, 5 or 10 mg/kg), to those of a known neurotoxin, methamphetamine (METH, at a 7.5 mg/kg dose), given i.p. at 2-h intervals, simultaneously on extracellular levels of glutamate [Gluext] and 5-HT [5-HText] in the ventral hippocampus (VHPC) using in vivo microdialysis in conscious rats. METH markedly increased both [Gluext] (+77% over the control value in saline-treated rats) and [5-HText] (around +250% over controls) in the VHPC. d-Fenfluramine, at all the doses studied, induced gradual increases of [5-HText] in the VHPC (between +125% and +417% over control values), but did not modify [Gluext]. These data highlight marked in vivo differences between METH and d-Fenfluramine in their effects on extracellular levels of 5-HT and Glu in the rat ventral hippocampus following their repeated systemic administration.

What do mitochondrial diseases teach us about normal mitochondrial functions...that we already knew: threshold expression of mitochondrial defects.

This paper shows how metabolic control analysis (MCA) can help to explain two important features of mitochondrial diseases: (i) the existence of a threshold in the expression of the complex deficiencies on the respiratory flux or on ATP synthesis, i.e. the fact that it is necessary to have a large complex deficiency in order to observe a substantial decrease in these fluxes; (ii) the tissue specificity, i.e. the fact that all tissues are not affected, even if the complex deficiency is present in all of them. We also show the limits of MCA, particularly when considering the in vivo situation. However, MCA offers a new way to consider mitochondrial diseases. The fact that fluxes only slightly change, when a complex is affected, is done at the expense of great changes in intermediate metabolite concentrations; intermediate metabolites situated upstream from the deficient complex are more reduced, leading to a greater generation of free radicals. This could bring an explanation for the diseases observed in conditions where the mitochondrial rate of ATP synthesis is only slightly affected.

Effect of a pulsed magnetic field and of first cold-pressure sunflower oil on mice.

In previous studies it has been shown that exposure of mice to a 12-Hz 6 mT unipolar square pulsed magnetic field (PMF) suppressed the excess of weight due to application of 1st cold-pressure sunflower oil. This time we considered the effect of oil and/or PMF on the growing curves lifespans of mice. The exposure took place for 30 min 5 days a week, from the 7th week of life to death. The results are 1) a broken slope in the growing curves from the 125th day of aging: the exposed mice were lighter than the controls, keeping the differences between the growing curves needed a repeated exposure all life long; 2) a significant increase in the lifespan of the controls which received oil versus the controls which received water; 3) an increase in the lifespan of the exposed mice versus the non-exposed control batches. On one hand it has been reported that essential polyunsaturated fatty acids found in first cold-pressure sunflower oil played a prominent role in membrane structures and in immune equilibrium. On the other hand, it was shown that oscillating electric fields could activate Na+K+-ATPase.

Tissue variation in the control of oxidative phosphorylation: implication for mitochondrial diseases.

Metabolic control analysis has often been used for quantitative studies of the regulation of mitochondrial oxidative phosphorylations (OXPHOS). The main contribution of this work has been to show that the control of mitochondrial metabolic fluxes can be shared among several steps of the oxidative phosphorylation process, and that this distribution can vary according to the steady state and the tissue. However, these studies do not show whether this observed variation in the OXPHOS control is due to the experimental conditions or to the nature of the mitochondria. To find out if there actually exists a tissue variation in the distribution of OXPHOS control coefficients, we determined the control coefficients of seven OXPHOS complexes on the oxygen-consumption flux in rat mitochondria isolated from five different tissues under identical experimental conditions. Thus in this work, only the nature of the mitochondria can be responsible for any variation detected in the control coefficient values between different tissues. The analysis of control coefficient distribution shows two tissue groups: (i) the muscle and the heart, controlled essentially at the level of the respiratory chain; and (ii) the liver, the kidney and the brain, controlled mainly at the phosphorylation level by ATP synthase and the phosphate carrier. We propose that this variation in control coefficient according to the tissue origin of the mitochondria can explain part of the tissue specificity observed in mitochondrial cytopathies.

Fragmentos de vellosidades coriónicas en muestras cervicales / Villous chorionic fragments in cervix samples

Extendidos cervicales de tres casos de postparto y un caso de postaborto fueron procesados con la técnica de Papanicolaou. El método de Estrepto-Avidina-Biotina se aplicó para detectar Gonofotrofina coriónica. En los cuatro casos fueron observados estructuras tridimensionales, ramificadas, con una zona central amorfa cubierta por células aplanadas de núcleo delgado, interpretadas como fragmentos de vellosidades coriónicas. En uno de los casos estos fragmentos estaban acompañados por células deciduales, en otro por células multinucleadas interpretadas como sincicio.trofoblasto, mientras que otra paciente presentaba células con características de citotrofoblasto. En coincidencia con las referencias bibliográficas, no se detectó Gonadotrofina coriónica en ninguno de los casos estudiados. el reconocimiento de fragmentos de vellosidades coriónicas podría facilitar la identificación de células placentarias atípicas que pueden ser confundidas con células displásicas o malignas, un error reconocido en este tipo de materiales

Mitochondrial creatine kinase functional development in post-natal rat skeletal muscle. A combined polarographic/31P NMR study.

Mitochondrial creatine kinase (Mi-CK) function in viable mitochondria from developing rat skeletal muscle was assessed both by polarographic measurements of creatine-induced respiration and 31P NMR spectroscopy measurements of phosphocreatine (PCr) synthesis. Creatine-induced respiration was observed in very young rats and increased by 50% to 35 days of age. PCr synthesis was present in 7 day old animals and increased by 300% reaching levels measured in 35 day and adult muscle. Unlike reports showing Mi-CK enzymatic activities but no mitochondrial function in several situations, a concomitant progression of enzymatic activity and mitochondrial function was evidenced during the developmental stages of skeletal muscle Mi-CK in altricious animals. These results correlated with the progressive pattern of muscle differentiation during development of motricity in such animals. The observation that Mi-CK is functional in skeletal muscle mitochondria very early after birth, strongly favors the notion that adaptations in skeletal muscle of Mi-CK knock-out mice occur early.

Simultaneous effects of local dexfenfluramine application on extracellular glutamate and serotonin levels in rat frontal cortex: a reverse microdialysis study.

We examined the effects of local perfusion by reverse dialysis of various doses of dexfenfluramine (D-fen; in mM: 2.4, 12, and 24) simultaneously on serotonin (5-HT; [5-HT]ext) and glutamate (Glu; [Glu]ext) extracellular levels in the frontal cortex of awake rats. D-fen induced a dose-dependent increase in both [5-HT]ext and [Glu]ext, the latter being Ca2+ -dependent and TTX-sensitive, while the former is not. Pretreatment with either the neurotoxin p-chloroamphetamine or the 5-HT uptake blocker fluoxetine, markedly reduced the effects of D-fen on [5-HT]ext and [Glu]ext compared to controls. This indicates that intact 5-HT nerve terminals may be required for D-fen to enter into neurones to release 5-HT by reversal of the 5-HT transporter, which then increases frontocortical [Glu]ext. Pretreatment with the Glu uptake blocker, L-trans-pyrrolidine-2,4-dicarboxylic acid (1 mM), significantly reduced by 40% the effect of D-fen's on [Glu]ext suggesting that Glu uptake sites are partially involved in this effect. These results strongly suggest that intracortical application, by reverse dialysis, of a high dose of D-fen increases frontocortical [Glu]ext by a dual mechanism of action: (1) by stimulating 5-HT release (a major indirect effect) that, in turn, facilitates the release of neuronal Glu; (2) by reversal of the glutamate transporter (a minor direct effect being Ca2+ -independent and TTX-insensitive).

Effect of pulsed magnetic fields on triglyceride and cholesterol levels in plasma of rats.

BACKGROUND: Liver is a crucial organ in metabolism. For instance liver is the main source of circulating lipoproteins. METHODS: In this paper cholesterol and triglyceride plasma levels were measured in male rats previously exposed to pulsed magnetic fields (PMF) used in therapy. Rats underwent a one-hour exposure to a 6 mT 12 Hz PMF. RESULTS: Twenty-four hours after the end of the exposure to the PMF the rats' livers were heavier, cholesterol and triglyceride plasma levels decreased. All these variations were significantly different according to a variance ratio test as was a rebound in triglyceride level 48 hours after the end of the exposure. Normal values were observed 48 and 96 hours after the end of exposure respectively for cholesterol and triglycerides. CONCLUSIONS: These alterations may be due to a reversible accumulation of either triglycerides or of their precursors in liver following acute exposure to a 12 Hz PMF.

Identification of five new genes, closely related to the interleukin-1beta converting enzyme gene, that do not encode functional proteases.

Interleukin-1beta converting enzyme (ICE) was the first identified member of a growing family of cysteine proteases that now includes ten mammalian homologs. Within this large family, two functional proteins, denoted TX and TY share 60% amino-acid identity with ICE in the mature protein and, together with ICE, constitute the ICE subfamily. The present study describes the identification of five new gene sequences, denoted S1-S5, closely related to ICE and TX and belonging to this subfamily. Sequences were identified using genomic Southern-blot analysis of human DNA with probes corresponding to ICE and TX exon 6. Using PCR amplification and cloning, the complete exon-6 sequence of these new genes was identified; three exhibit around 90% identity with Ice within exon 6, whereas the two others share about 70% identity with Ice. Examination of open reading frames and of amino acids essential for ICE activity indicate that none of these genes encodes for a functional protease. In conclusion, extensive analysis of the genes closely related to Ice shows that the Ice subfamily is constituted of eight members. Three of them encode for functional proteases (ICE, TX and TY) whereas the remaining members probably correspond to pseudogenes.

Microdialysis monitoring of variations in extracellular levels of serotonin, GABA and excitatory amino acids in the frontal cortex of awake rats in response to a single peripheral or central administration of dexfenfluramine.

The effects of a single dexfenfluramine (D-fen) administration on the release of endogenous serotonin (5-hydroxytryptamine, 5-HT), excitatory (glutamate, Glu, aspartate, Asp) and inhibitory (gamma-aminobutyric acid, GABA) amino acids from the frontal cortex were studied by using in vivo microdialysis in freely-moving rats. Extracellular levels of these neurotransmitters were measured with HPLC coupled to electrochemical detection or with capillary electrophoresis coupled to laser-induced fluoresence detection (CE-LIFD). In a first study, single intraperitoneal administration of D-fen (0.5, 1.3, 5 and 10 mg/kg) increased extracellular 5-HT levels in a dose-dependent manner (maximal increase by 982% over baseline for the highest dose) while changes in Glu, Asp or GABA never reached statistical significance. In a second study, 73 nM of D-fen applied locally through the frontocortical dialysis probe, at a flow rate of 1.5 microliters/min in 30 microliters of perfusion fluid for 20 min, increased extracellular 5-HT and Asp levels [the maximal increases were to 1804% and 280% of the respective basal values (100%)] without altering extracellular levels of Glu and GABA. Thus, the order of magnitude of the changes induced by systemic administration or local infusion of D-fen on frontocortical extracellular levels of several neurotransmitters (5-HT > > Asp > GABA = Glu) demonstrate that D-fen, an indirect serotoninergic agonist, mainly increases 5-HT release while producing slight (Asp) or no (Glu, GABA) short-term in vivo variations in amino acid extracellular levels in the rat frontal cortex.