We designed a model-based analysis to predict the occurrence of population patterns in distributed spiking activity. Using a maximum entropy principle with a Markovian assumption, we obtain a model ...that accounts for both spatial and temporal pairwise correlations among neurons. This model is tested on data generated with a Glauber spin-glass system and is shown to correctly predict the occurrence probabilities of spatiotemporal patterns significantly better than Ising models only based on spatial correlations. This increase of predictability was also observed on experimental data recorded in parietal cortex during slow-wave sleep. This approach can also be used to generate surrogates that reproduce the spatial and temporal correlations of a given data set.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Many efforts have been devoted to modeling asynchronous irregular (AI) activity states, which resemble the complex activity states seen in the cerebral cortex of awake animals. Most of models have ...considered balanced networks of excitatory and inhibitory spiking neurons in which AI states are sustained through recurrent sparse connectivity, with or without external input. In this letter we propose a mesoscopic description of such AI states. Using master equation formalism, we derive a second-order mean-field set of ordinary differential equations describing the temporal evolution of randomly connected balanced networks. This formalism takes into account finite size effects and is applicable to any neuron model as long as its transfer function can be characterized. We compare the predictions of this approach with numerical simulations for different network configurations and parameter spaces. Considering the randomly connected network as a unit, this approach could be used to build large-scale networks of such connected units, with an aim to model activity states constrained by macroscopic measurements, such as voltage-sensitive dye imaging.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Flavonol compounds of three Mediterranean plants from the Algerian Atlas used traditionally in Arab folk medicine,
Arenaria serpyllifolia,
Rhamnus alaternus and
Thapsia garganica, were found to ...inhibit the enzymatic activities of both rat intestine and purified porcine liver carboxylesterase in a concentration-dependent manner. Results indicate that the flavonol compounds from the aerial part of these plants lead to the inactivation of the CE pI = 5.1 with
K
i of micromolar range. These results encourage us to perform further biological investigation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
After administering the equivalent of 1 g of eicosapentaenoic acid (EPA) in four different chemical forms, the kinetics of EPA incorporation into plasma triglycerides (TG) were compared by gas liquid ...chromatography on a capillary column following separation of the lipid fraction by thin layer chromatography. EPA incorporation into plasma TG was markedly smaller and later when EPA was administered as an ethyl ester rather than as EPA free fatty acid, EPA arginine salt or 1,3-dioctanoyl-2-eicosapentaenoyl glycerol (2-EPA). Our results and the data in the literature are compatible with the hypothesis that 2-EPA is absorbed with minimum hydrolysis and escapes random distribution between the other positions of the glycerol molecule during the absorption process.
In transplanted hearts, peri- and postoperative ischemic and alloimmune stimuli may be interpreted as inadequate tissue perfusion leading to activation of angiogenic signaling. Placenta growth factor ...(PLGF) is a marker of neoangiogenesis, belonge to vascular endothelial growth factors (VEGF) family. It has been shown that PLGF serum levels are elevated during acute rejection and decrease after immunosuppressive therapy in pediatric heart transplant recipients. The study was aimed to investigate clinical and prognostic significance of PLGF in heart transplant recipients. 34 patients (pts) (42,5 ± 8,5 years, 29 men and 5 women, 21 patient with dilated cardiomyopathy, 13 – with ischemic heart disease) underwent heart transplantation (HTx) and were examined before and after HTx. Our results showed that pretransplant PLGF is a marker of posttransplant cardiovascular risk. Revealing PLGF plasma level in recipients during the first year after HTx also has prognostic value concerning development of cardiovascular complications. In the remote terms (1–16 years) after HTx PLGF plasma levels were significantly higher in recipients with TxCAD than in recipients without TxCAD. These findings confirm participation of PLGF in damage of the transplanted heart vessels.
The conversion of dihomogamma linolenic acid (DHLA) into arachidonic acid (AA) was compared in normal subjects and diabetic patients before and after treatment with insulin. The kinetics of the ...incorporation of deuterium-labeled DHLA and its conversion product, deuterium-labeled AA, was determined in plasma triglycerides, plasma phospholipids, and platelet lipids of subjects after ingestion of 2 g of the labeled precursor. Analysis was performed by gas liquid chromatography-mass spectrometry using multiple ion detection. In normal subjects, the deuterium-labeled DHLA concentration rose to 24 to 69 mg/L in plasma triglycerides four to nine hours after ingestion and to 20 to 34 mg/L in plasma phospholipids about four hours later. Deuterium-labeled AA appeared at 12 hours, rose to 2.4 to 3.8 mg/L between 48 and 72 hours in plasma phospholipids, but remained at the limit of detection in plasma triglycerides and was undetectable in platelet lipids. In diabetic patients both before and after insulin treatment, the deuterium-labeled DHLA concentration in plasma triglycerides and in plasma phospholipids followed the same pattern as in normal subjects. However, the deuterium-labeled arachidonic acid concentration was below 1 mg/L in plasma phospholipids before insulin. After insulin treatment the patients recovered normal DHLA metabolism because deuterium-labeled AA rose in phospholipids to a mean value of 3.5 mg/L, which is in the same range as that observed in normal subjects (3.2 mg/L). The present data provide direct evidence for the conversion of DHLA into AA in humans. The effect of insulin and the data from the literature of animal studies suggest insulin dependence of delta 5 desaturase in humans.
The inhibition of enzymatic browning and oxidation is still an important challenge in food processing. This study was designed to examine in vitro the inhibition of enzymatic browning in apple and ...the antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferrous ion chelating activity by Mentha suaveolens phenol, methanol and aqueous extracts. The use of various extracts in the prevention of the enzymatic browning, catalysed by polyphenol oxidases (PPO) and peroxidases (POD) showed that the phenol extract had a high effect on PPO more than synthetic inhibitor (potassium sorbate), whereas all extracts of M. suaveolens presented only a minor effect on POD of apple. The radical scavenging activity of various extracts of M. suaveolens using DPPH showed that the phenol extract had same activity as butyl hydroxyl toluene (BHT) which is a known inhibitor for its antioxidant activity. The highest ferrous ion chelating activity was found in phenol and methanol extracts. The chemical analysis of the phenol extract using the high performance liquid chromatography (HPLC) suggests that the rosmarinic acid could explain the observed inhibition. In conclusion, these data suggest that the M. suaveolens compounds can act as preservatives of food against oxidation and enzymatic browning.
Primary culture of hepatocytes from puromycin aminonucleoside-induced nephrotic rats were used to discriminate between the hepatic and extra-hepatic contribution to the hyperlipidemia occurring in ...the nephrotic syndrome. De novo lipogenesis and utilization of exogenous fatty acids were not modified in nephrotic hepatocytes as compared to controls. In contrast 2.2 and 5.3-fold more triacylglycerol and phospholipids were secreted respectively by nephrotic hepatocytes than by controls. Triacylglycerol overproduction was not associated with an increase either in apo B mRNA level or in apo B synthesis or secretion measured by 35S-methionine incorporation and immunoprecipitation. We also observed a significant increase in apo AI and apo E synthesis and secretion by nephrotic hepatocytes. This increase was correlated with a greater amount of apo AI and apo E mRNA than in controls. The overproduction of apo AI and apo E by nephrotic hepatocytes might intervene in the clearance of plasma lipoproteins and the redistribution of plasma cholesterol.
