Dibenzodioxocinones--a new class of CETP inhibitors

Derivatives of the natural product 11-hydroxy-3-[(S)-1-hydroxy-3-methylbutyl]-4-methoxy-9-methyl-5H,7H-dibenzo[b,g][1,5]dioxocin-5-one 1 were studied as novel CETP inhibitors. Compound 2 was identified from HTS as a micromolar inhibitor. The compound suffered from very low stability in plasma. Optimisation by partial synthesis started from 1 and led to low-nanomolar inhibitors with good stability in rat plasma.     

Fenofibrate induces HDL-associated PAF-AH but attenuates enzyme activity associated with apoB-containing lipoproteins

Human plasma platelet-activating factor acetylhydrolase (PAF-AH) is an enzyme associated mainly with the apolipoprotein B (apoB)-containing lipoproteins and primarily with LDL. A small proportion of enzymatic activity is also associated with HDL. Plasma paraoxonase 1 (PON1) is an esterase exclusively associated with HDL. The effect of fenofibrate on PAF-AH and PON1 activities in patients with dyslipidemias of Types IIA, IIB, and IV were studied. Fenofibrate reduced plasma PAF-AH activity in all patient groups. In Type IIA patients, this reduction was mainly due to a fall in enzyme activity associated with the dense LDL subspecies, whereas in Type IIB and Type IV patients, it was due to the decrease in PAF-AH activity associated with both the VLDL+IDL and dense LDL subspecies. Drug therapy in Type IIB and Type IV patients significantly increased the HDL-associated PAF-AH activity due to the increase in enzyme activity associated with the HDL-3c subfraction. Fenofibrate did not affect serum PON1 activities toward paraoxon and phenylacetate in either patient group. The fenofibrate-induced elevation of HDL-associated PAF-AH activity in dyslipidemic patients of Type IIB and Type IV, as well as the reduction in enzyme activity associated with atherogenic apoB-containing lipoproteins in all patient groups, may represent a new and important antiatherogenic effect of this potent lipid-modulating agent.     

Altered distribution of platelet-activating factor- acetylhydrolase activity between LDL and HDL as a function of the severity of hypercholesterolemia

Platelet-activating factor-acetylhydrolase (PAF-AH) is a lipoprotein-associated phospholipase A2 capable of hydrolyzing platelet-activating factor (PAF) and oxidatively modified phospholipids. We studied the plasma- and lipoprotein-associated PAF-AH activity in patients with primary hypercholesterolemia. Thirty-eight unrelated patients with heterozygous familial hypercholesterolemia (HeteroFH), five patients with homozygous FH (HomoFH), and 33 patients with primary non-FH hypercholesterolemia (NonFH) participated in the study. In all patient groups the plasma PAF-AH activity was significantly elevated compared with 33 normolipidemic controls, the HomoFH having the highest and the NonFH patients showing the lowest enzyme activity. Gradient ultracentrifugation studies showed that this increase is not only due to the elevation in the plasma LDL but also to the increase in the PAF-AH activity associated with each LDL subfraction, being more profound in the small-dense LDL-5. Unlike LDL, no difference in the HDL-associated PAF-AH activity was observed among all groups. Consequently, an altered distribution of enzyme activity among apolipoprotein B (apoB)- and apolipoprotein A-I (apoA-I)-containing lipoproteins is observed in hypercholesterolemic patients, resulting in a significant decrease in the ratio of the HDL-associated PAF-AH to the total plasma enzyme activity compared with controls. This reduction is proportional to the increase of the plasma LDL-cholesterol (LDL-C) levels and consequently to the severity of the hypercholesterolemia. Thus, the ratio of HDL-associated PAF-AH-total plasma enzyme activity may be useful as a potential marker of atherogenicity in subjects with primary hypercholesterolemia.     

Citric acid production by Candida strains under intracellular nitrogen limitation

A suitable strain and important factors influencing citric acid formation in yeasts were identified. Candida oleophila ATCC 20177 was chosen as the best citric acid producer from several Candida strains. Yields of 50 g/l citric acid were produced in shake flask and 80 g/l in fed-batch fermentations with 1.5 and 3 g/l NH(4)Cl under non-optimized conditions. Ammonium nitrogen was identified as the limiting substrate for citrate formation. Citric acid excretion begins a few hours after exhaustion of nitrogen in the medium. The importance of intracellular nitrogen limitation was clarified by elemental analysis of C. oleophila biomass. The nitrogen content of C. oleophila biomass decreased from 7.45% during the growth phase to 3.96% in the production phase. The biomass contained less carbon and more trace elements in the growth phase compared with the production phase. Relatively high intracellular NH(4)(+) concentration of about 1.2 mg/g biomass (~37.4 mM) was found during the production phase. The low intracellular nitrogen content and increase of intracellular NH(4)(+) concentration, possibly caused by proteolysis following extracellular nitrogen exhaustion, trigger citric acid production. Intracellular nitrogen limitation and the increase in intracellular NH(4)(+) concentration are the most important factors influencing citric acid formation in yeasts.     

Use of a microbial sensor: inhibition effect of azo-reactive dyes on activated sludge

This paper summarizes the methodology utilized for measuring the toxic and inhibitory effects of azo-reactive dyes on the activity of activated sludge. The microbial sensor employed in this study consisted of a small-fluidized bed reactor in which the microbial mass was immobilized on spherical (diameter =1-2 mm) reticulated sinter glass carriers. To sustain a highly dense population of aerobic microbes, pure oxygen was supplied via a cylindrical chamber, which comprised part of the sample re-circulation system. The mean hydraulic retention time in the microbial sensor ranged between 30 and 40 min, while temperature was maintained at 30 degrees C and pH at 6.4. Inhibition of microbial activity (toxicity) was determined as the mean percent reduction in carbon dioxide production from microorganisms' respiration. Several azo-reactive dyes demonstrated toxicity when applied at a high concentration (2 g/l), however, a portion of the microbes showed tolerance to the dyes. Moreover, textile wastewater demonstrated very efficient biodegradation.     

A novel technique to evaluate interactions between Saccharomyces cerevisiae cell wall and mycotoxins: application to zearalenone

Three models based on sigmoidal plotting were tested for their ability to describe zearalenone adsorption on Saccharomyces cerevisiae cell walls in vitro. All three models closely fitted the experimental data, but Hill's equation gave the most accurate parameters, and provided information on the physical and chemical mechanisms involved in the adsorption of mycotoxin on yeast cell walls.     

Machine learning approaches to lung cancer prediction from mass spectra

We addressed the problem of discriminating between 24 diseased and 17 healthy specimens on the basis of protein mass spectra. To prepare the data, we performed mass to charge ratio (m/z) normalization, baseline elimination, and conversion of absolute peak height measures to height ratios. After preprocessing, the major difficulty encountered was the extremely large number of variables (1676 m/z values) versus the number of examples (41). Dimensionality reduction was treated as an integral part of the classification process; variable selection was coupled with model construction in a single ten-fold cross-validation loop. We explored different experimental setups involving two peak height representations, two variable selection methods, and six induction algorithms, all on both the original 1676-mass data set and on a prescreened 124-mass data set. Highest predictive accuracies (1-2 off-sample misclassifications) were achieved by a multilayer perceptron and Na?ve Bayes, with the latter displaying more consistent performance (hence greater reliability) over varying experimental conditions. We attempted to identify the most discriminant peaks (proteins) on the basis of scores assigned by the two variable selection methods and by neural network based sensitivity analysis. These three scoring schemes consistently ranked four peaks as the most relevant discriminators: 11683, 1403, 17350 and 66107.     

Autocrine and paracrine regulation of lymphocyte CB2 receptor expression by TGF-beta.

The marijuana-derived cannabinoid Delta(9)-tetrahydrocannabinol (THC) has been shown to be immunosuppressive. We report that THC induces the immunosuppressive cytokine TGF-beta by human peripheral blood lymphocytes (PBL). The ability of THC to stimulate TGF-beta production was blocked by the CB2 receptor specific antagonist SR144528 but not by the CB1 specific antagonist AM251. Furthermore, our data suggest that TGF-beta actively regulates lymphocyte CB2 receptor expression in an autocrine and paracrine manner. Whereas the addition of recombinant TGF-beta to PBL cultures downregulated CB2 receptor expression, anti-TGF-beta antibody treatment increased CB2 receptor expression. We conclude that one mechanism by which THC contributes to immune suppression is by stimulating an enhanced production of lymphocyte TGF-beta.     

Process optimization of continuous gluconic acid fermentation by isolated yeast-like strains of Aureobasidium pullulans

This study was focused on the optimization of a new fermentation process for continuous gluconic acid production by the isolated yeast-like strain Aureobasidium pullulans DSM 7085 (isolate 70). Operational fermentation parameters were optimized in chemostat cultures, using a defined glucose medium. Different optima were found for growth and gluconic acid production for each set of operation parameters. Highest productivity was recorded at pH values between 6.5 and 7.0 and temperatures between 29 and 31 degrees C. A gluconic acid concentration higher than 230 g/L was continuously produced at residence times of 12 h. A steady state extracellular gluconic acid concentration of 234 g/L was measured at pH 6.5. 122% air saturation yielded the highest volumetric productivity and product concentration. The biomass-specific productivity increased steadily upon raising air saturation. An intracellular gluconic acid concentration of about 159 g/L (0.83 mol) was determined at 31 degrees C. This is to be compared with an extracellular concentration of 223 g/L (1.16 mol), which indicates the possible existence of an active transport system for gluconic acid secretion, or the presence of extracellular glucose oxidizing enzymes. The new process provides significant advantages over the traditional discontinuous fungi operations. The process control becomes easier, thus offering stable product quality and quantity.