Characterization of the molecular heterogeneity of copolymers obtained via zwitterion by capillary zone electrophoresis

Summary Using capillary zone electrophoresis has made characterizations of different copolymers obtained via zwitterionic polymerization. Results demonstrate that this technique is able to put into evidence the molecular heterogeneity of the different copolymers. Analyses were performed in less than 10 minutes using a borate buffer. To our knowledge this the first time that free-zone capillary electrophoresis has been applied to the characterization of copolymers systems below the oligomer range obtained via zwitterion polymerization. Received: 27 April 2001/Revised version: 24 November 2001/ Accepted: 9 January 2002     

Modelling the aqueous extraction of soluble substances from ground roasted coffee

This work aims to study and model the extraction of soluble substances from coffee grounds having different particle sizes. The results demonstrate that coffee brewing cannot be considered a simple diffusion mechanism as reported in the literature. The phenomenon has two phases: a washing phase where surface soluble substances instantaneously dissolve and are transferred to the extract by a convection mechanism, and a diffusion phase involving the solubles within the porous particles. A model was set up to calculate extraction yield as the addition of the two phases. It was also demonstrated that the effect of washing shows a linear correlation with the external surface area of particles and that the composition of the extracts does not depend on extraction time.     

Use of a toasted durum whole meal in the production of a traditional Italian pasta: chemical, mechanical, sensory and image analyses

The characterisation of traditional Italian pasta obtained by mixing amounts of toasted whole meal with re-milled semolina and other ingredients was obtained by means of physico-chemical, rheological, mechanical, sensory and image analyses. The toasted meal showed higher ash, fibre and protein contents than re-milled semolina. The replacement of percentages of re-milled semolina with the toasted meal and soft flour increased tenacity and decreased extensibility and strength, making the dough less suitable for pasta-making. The P / L values were indices of high starch damage. The replacement of part of re-milled semolina and water with toasted whole wheat meal, soft flour and eggs increased the optimal cooking time and the amount of water absorbed during cooking but made the other cooking parameters worse. The image analysis provided evidence of the changes induced by the use of toasted wholemeal, soft flour and eggs in the microscopic structure of pasta protein and starch.     

Nanoparticle Removal Using Laser-Induced Plasma Shock Waves

Removal of sub-100 nm particles from substrates such as wafers and photo masks is an essential requirement in semiconductor, microelectronics, and nanotechnology applications. The proposed laser-induced plasma (LIP) based approach is an effective technique for removal of sub-100 nm particles, as the minimum tolerable particle on the substrates shrinks to sub-100 nm levels with each technological node. In the current study, our progress in sub-100 nm particle removal is reviewed, and the results of the kinetic theory simulations conducted to understand the dynamics of the gas molecule-nanoparticle interactions excited by the shock front are discussed. It is shown from the simulations and experiments that particles as small as sub-100 nm can be successfully detached. To explain possible mechanisms for the nanoparticle detachment in nanoscale, the concepts of rolling resistance moment and rocking motion are utilized as novel detachment mechanisms. The pressure experiments illustrate that the peak pressure levels achieved with the LIP shock wave fields are below damage thresholds of most substrate materials. The potential of the proposed approach as a practical noncontact, dry, fast, and damage-free method for removal of sub-100 nm particles is discussed.     

The role of prostaglandins in allergic inflammation

Prostaglandins likewise leukotriens are proinflammatory mediators resulting from metabolic degradation of the arachidonic acid originating from membrane phospholipids. The most important products of enzyme cyclooxygenation of arachidonic acid are prostaglandins D2, E2, F2a, tromboxane A2 and prostacyclin. Prostaglandins express their tissue effects via the five basic receptor types. Within the allergic inflammation activated mast cell synthesizes prostaglandin D2 (first lipid mediator) which has bronchoconstrictive and vasodilating effects and attracts neutrophilic leukocytes. Moreover, it also participates in the late phase reactions, six hours subsequent to the exposure to the allergen. This mediator is also important in pathogenesis of urticaria, allergic rhinitis and allergic bronchial asthma. In addition to prostaglandin D2, prostaglandin F2a and tromboxane A2 also have bronchoconstrictive actions, while prostacyclin and prostaglandin E have bronchodilating effects. Inhalation of prostaglandin E prevents asthmatic attacks caused by allergens, strain, metabisulfite and ameliorates attacks of aspirin asthma, which confirms the hypothesis that aspirin asthma is based on cyclooxigenase inhibition and increased leukotriene production. In patients with atopic dermatitis, prostaglandin E has suppressive effects on Interferon gamma production by Th1 helper cells and increases production of Interleukin 4 by the Th2 cells. Tromboxane A2 plays a certain role in the development of bronchial hyperreactivity and late asthmatic response. Prostaglandins are also important mediators in the pathogenesis of allergic conjunctivitis. Most of nonsteroidal antiinflammatory drugs inhibit the enzyme cyclooxygenase and thus also prostaglandin biosynthesis and release.     

The effects of levcromakalim and pinacidil on the human internal mammary artery

The present study was undertaken to examine the effects of pinacidil and levcromakalim, two potassium, channel openers, on human internal mammary artery (HIMA) obtained from patients undergoing coronary artery bypass surgery, and to clarify the contribution of different K+ channel subtypes in pinacidil and levcromakalim action in this blood vessel. Pinacidil and levcromakalim induced a concentration-dependent relaxation of the precontracted arterial segments (pEC50 = 5.77 +/- 0.05 and 6.89 +/- 0.03, respectively), 4-Aminopyridine (3 mM), a non-selective blocker of K+ channels, induced significant shifts to the right of the concentration-response curves for pinacidil and levcromakalim. Tetraethylammonium (6 mM), charybdotoxin (0.4 microM) and apamin (0.1 microM), blockers of Ca(2+)-sensitive K+ channels, had no effect on the pinacidil- and levcromakalim-evoked relaxation. Glibenclamide (0.1-10 microM), a selective blocker of adenosine triphosphate (ATP)-sensitive K+ channels, competitively antagonized the response to levcromakalim (pKB = 7.92 +/- 0.07). In contrast, glibenclamide, in significantly higher concentrations (3-30 microM), non-competitively antagonized the response to pinacidil. High concentrations of pinacidil (> 10 microM) relaxed arterial rings bathed by a medium containing 100 mM K+ with maximum response 83 +/- 6%. Under the same conditions, the maximum levcromakalim-induced relaxation on HIMA was almost abolished (15 +/- 2%). It is concluded that pinacidil and levcromakalim do not relax the HIMA through the same subtype of K+ channel. ATP-sensitive K+ channels are probably involved in levcromakalim- but not in a pinacidil-induced relaxation in the HIMA. In addition, in pinacidil-induced relaxation of the HIMA, K+ channel-independent mechanisms seem to be involved.     

Acute ethanol hepatotoxicity is modulated by bile salt hydrophilic-hydrophobic properties

The influence of the hydrophobic-hydrophilic properties of bile salts (BS) on acute ethanol hepatotoxicity was investigated. Bile flow, biliary BS secretion and enzyme (LDH,AST) release in the perfusate were measured before and after exposure to low (0.1%) or high (1%) doses of ethanol in in vitro isolated livers perfused with 1 microM/min taurocholate (TCA), tauroursodeoxycholate (TUDCA) or taurodeoxycholate (TDCA). Ethanol promotes a rapid decrease of basal bile flow and BS secretion in TCA-perfused livers [-28% of basal values with 0.1% (N = 6), and -35% with 1% ethanol (N = 6)]. Bile flow and BS secretion were minimally decreased by ethanol in livers perfused with a hydrophilic BS (TUDCA) [-8% decrease of basal values with 0.1% ethanol (N = 6), and -10% with 1% ethanol (N = 9); p < 0.02 vs TCA-perfused livers]. In contrast, when livers were perfused with a hydrophobic BS (TDCA), ethanol showed a higher cholestatic effect than either TCA- or TUDCA-perfused livers. Enzyme release in the perfusate was not modified by 0.1% ethanol, while 1% ethanol promoted a 4-5 fold increase in LDH and AST release in the perfusate of TCA-perfused livers with respect to a mere 2-fold increase in TUDCA-perfused livers and a 6-7 fold increase in TDCA perfused livers (p < 0.03). In conclusion, we showed that TUDCA almost completely counteracts the cholestatic and cytolitic effects promoted by ethanol in the isolated perfused rat liver.     

Leukotrienes in allergic inflammatory reactions

Production of leukotrienes, lipooxygenase products of arachidonic acid metabolism, plays an important role in inflammatory reactions, particularly well studied in bronchial asthma. Lipooxigenase-5 and lipooxygenase-activating protein-5 are crucial in the production of leukotrienes with potent biological activities. Leukotriene B4 is a leukocytic chemoattractant and it induces aggregation and adherence of leukocytes to endothelial vasculature. Sulfidopeptid leukotrienes (C4, D4 and E4) are potent bronchoconstrictors, producing mucous secretion in the airways and increasing vascular permeability. Leukotrienes participate in the process of inflammation, as well as in early and late asthmatic responses. They are found in the blood, liquid obtained upon bronchoalveolar lavage as well as in the urine, irrespectively whether bronchospasm developed spontaneously or it was induced by an allergen. Administration of the specific leukotriene receptor antagonists or leukotriene synthesis inhibitors ameliorates the symptoms and signs of bronchial asthma.     

Maderisation of white wines: I.—Influence of pressing on the susceptibility of the grapes to oxidative browning

The oxidative browning of white wines (maderisation) obtained by fermenting musts derived from progressive pressing cycles, was studied in relation to the phenolic concentration. A picture of the distribution of the various phenolics was obtained by combining the total phenolics determination with selective precipitation of flavonoids with formaldehyde and tannins with cinchonine. Both enzymic and non-enzymic browning are directly related to the flavonoids concentration in the wines; a progressive insolubilisation of tannic flavonoids and a polymerisation of the non-tannic flavonoids accompanies the colour change. The concentration of non-flavonoid phenolics does not vary significantly during oxidative degradation and therefore they tend to become the most representative phenolic fraction in the maderised wines.