Colorimetric investigation of the reaction between p-phenylendiamine and meta-substituted derivatives of benzene on a model support.

The aim of this work was the employment of colorimetric techniques in the analysis of the color formed, on a proteic substrate, by the reaction between p-phenylendiamine and some meta-substituted benzene derivatives in the presence of hydrogen peroxide and in media at different pH values. In particular we investigated the chromatic variations that take place on the substrate in dependence on different reaction conditions. The obtained results show that for each couple of reagents the colorimetric data, namely the reflectance of the formed color, change considerably with the pH of the reaction medium and demonstrate how this parameter can be considered a good descriptor of the composition of the formed pigment.

Inducible expression of maize polyamine oxidase in the nucleus of MCF-7 human breast cancer cells confers sensitivity to etoposide.

In this study, polyamine oxidase from maize (MPAO), which is involved in the terminal catabolism of spermidine and spermine to produce an aminoaldehyde, 1,3-diaminopropane and H(2)O(2), has been conditionally expressed at high levels in the nucleus of MCF-7 human breast cancer cells, with the aim to interfere with polyamine homeostasis and cell proliferation. Recombinant MPAO expression induced accumulation of a high amount of 1,3-diaminopropane, an increase of putrescine levels and no alteration in the cellular content of spermine and spermidine. Furthermore, recombinant MPAO expression did not interfere with cell growth of MCF-7 cells under normal conditions but it did confer higher growth sensitivity to etoposide, a DNA topoisomerase II inhibitor widely used as antineoplastic drug. These data suggest polyamine oxidases as a potential tool to improve the efficiency of antiproliferative agents despite the difficulty to interfere with cellular homeostasis of spermine and spermidine.

Biodegradable hydrogels obtained by photocrosslinking of dextran and polyaspartamide derivatives.

The functionalization of dextran with glycidyl methacrylate (GMA) leads to the formation of a derivative that generates hydrogels for irradiation at 365nm. The effects of various polymer concentrations and irradiation times on the yield and the properties of the obtained hydrogels are reported. The networks have been characterized by FT-IR spectra, dimensional analysis and swelling measurements carried out at different pH values. In vitro studies suggest that all samples undergo a partial chemical hydrolysis, whereas the incubation with dextranases causes a total degradation whose rate depends on the degree of crosslinking. In addition, aqueous solutions of functionalized dextran have been irradiated in the presence of PHG (PHEA-GMA), i.e. the copolymer obtained by the reaction of alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) with GMA. The crosslinking reaction leads to the formation of new networks containing both polymers whose properties have been investigated. To evaluate the processes which occur during UV irradiation, the sol fractions have been purified and characterized by FT-IR and 1H-NMR analyses. Finally, the suitability of hydrogels deriving from functionalized dextran, crosslinked alone or in the presence of PHG, for drug delivery systems has been investigated choosing theophylline as a model drug.

Role of membrane fluidity in pressure resistance of Escherichia coli NCTC 8164.

The relationship among growth temperature, membrane fatty acid composition, and pressure resistance was examined in Escherichia coli NCTC 8164. The pressure resistance of exponential-phase cells was maximal in cells grown at 10 degrees C and decreased with increasing growth temperatures up to 45 degrees C. By contrast, the pressure resistance of stationary-phase cells was lowest in cells grown at 10 degrees C and increased with increasing growth temperature, reaching a maximum at 30 to 37 degrees C before decreasing at 45 degrees C. The proportion of unsaturated fatty acids in the membrane lipids decreased with increasing growth temperature in both exponential- and stationary-phase cells and correlated closely with the melting point of the phospholipids extracted from whole cells examined by differential scanning calorimetry. Therefore, in exponential-phase cells, pressure resistance increased with greater membrane fluidity, whereas in stationary-phase cells, there was apparently no simple relationship between membrane fluidity and pressure resistance. When exponential-phase or stationary-phase cells were pressure treated at different temperatures, resistance in both cell types increased with increasing temperatures of pressurization (between 10 and 30 degrees C). Based on the above observations, we propose that membrane fluidity affects the pressure resistance of exponential- and stationary-phase cells in a similar way, but it is the dominant factor in exponential-phase cells whereas in stationary-phase cells, its effects are superimposed on a separate but larger effect of the physiological stationary-phase response that is itself temperature dependent.

Heat resistance of Paenibacillus polymyxa in relation to pH and acidulants.

The efficacy of different organic acids in decreasing the heat resistance of Paenibacillus polymyxa spores was assessed. The relationship between concentration of the undissociated form of different organic acids and decrease in heat resistance was also investigated. The heat resistance of P. polymyxa spores was tested in distilled water at 85, 90 and 95 degrees C, at pH4 and in the presence of 50, 100 and 200 mmol l(-1) of the undissociated form of lactic, citric or acetic acid and sodium citrate or acetate. The undissociated form of organic acids was responsible for increasing the heat sensitivity of spores. The most effective acid was lactic acid. The D values of the spores decreased rapidly (between 74 and 43%) in the presence of 50 mmol l(-1) of the undissociated form of organic acid, and increasing concentrations of these forms affected the heat resistance of spores less than proportionally. The heat resistance of the spores in milk was approximately threefold lower than in distilled water. This work has shown that the undissociated fraction of organic acids increases, albeit non-linearly, the sensitivity of spores to heat, even in complex substrates such as milk. By knowing the amount of organic acids added to a given substrate, their dissociation constants and the final pH, it could be possible to estimate the concentration of undissociated forms and the corresponding increase in lethality of heat treatments. This would help the food industry to maximize the lethality achieved by heat processes and/or safely reduce the heat treatments already in use.

Variation in resistance of natural isolates of Escherichia coli O157 to high hydrostatic pressure, mild heat, and other stresses.

Strains of Escherichia coli O157 isolated from patients with clinical cases of food-borne illness and other sources exhibited wide differences in resistance to high hydrostatic pressure. The most pressure-resistant strains were also more resistant to mild heat than other strains. Strain C9490, a representative pressure-resistant strain, was also more resistant to acid, oxidative, and osmotic stresses than the pressure-sensitive strain NCTC 12079. Most of these differences in resistance were observed only in stationary-phase cells, the only exception being acid resistance, where differences were also apparent in the exponential phase. Membrane damage in pressure-treated cells was revealed by increased uptake of the fluorescent dyes ethidium bromide and propidium iodide. When strains were exposed to the same pressure for different lengths of time, the pressure-sensitive strains took up stain sooner than the more resistant strain, which suggested that the differences in resistance may be related to susceptibility to membrane damage. Our results emphasize the importance of including stress-resistant strains of E. coli O157 when the efficacy of a novel or mild food preservation treatment is tested.

Heat resistance of Listeria monocytogenes in dairy products as affected by the growth medium.

Listeria monocytogenes strains 1151 and Scott A were grown in broth at 30 degrees C and transferred to half cream, double cream and butter stored at 5 degrees C to determine the influence of dairy product composition on heat resistance at 52, 56, 60, 64 and 68 degrees C. Strain 1151 showed a higher heat resistance than strain Scott A. The heat resistance of both strains was higher in the dairy products than in broth, particularly at lower temperatures. A significant difference was observed between log 10 of the D-values in the different dairy products. The D-values obtained for both strains resuspended in all the dairy products would result in efficient elimination of the pathogen at 72.7 degrees C for 15 s. The highest D-value was 11.30 s at 68 degrees C and by using a z-value of 6.71 degrees C it can be determined that at 72.7 degrees C the D-value would be 1.5 s. The 15 s process would therefore achieve 10 log reductions. The effect of growth conditions on the heat resistance at 60 degrees C of L. monocytogenes Scott A was also investigated. When the cells were grown in the diary products themselves, and particularly butter, the heat resistance of Scott A was enhanced; for example, the D-values were 7.15 times higher than in broth. Further studies are required to investigate if this protection against heating exists at higher temperatures, in which case the efficiency of pasteurization treatments or other heat treatments would be considerably lowered.

Effect of centrifugation on the pressure resistance of exponential phase cells of Escherichia coli 8164.

Exponential phase cells of Escherichia coli NCTC 8164 that were centrifuged at 2000 g for 20 min at 4 degrees C were more resistant to subsequent pressure treatment than cells grown in trypticase soya broth (TSB) and treated without any centrifugation steps. The effects of mild pressure stress (200 kPa for 20 min) and temperature stress (a shift from 37 degrees C to 4 degrees C) involved in the centrifugation procedure were analysed separately. It appeared that the increase in pressure resistance obtained following centrifugation was mainly due to the gradual temperature decrease during centrifugation, while the mild pressure stress seemed to play a smaller role in the response.

Effects of erdosteine on sputum biochemical and rheologic properties: pharmacokinetics in chronic obstructive lung disease.

Erdosteine is a new thioderivative endowed with mucokinetic, mucolytic, and free-radical-scavenging properties. This study evaluated (in a double-blind design vs. placebo) its efficacy on biochemical and rheologic properties of sputum and on some indices of respiratory function in chronic patients with chronic bronchitis (10 per group), while receiving basic treatment with a controlled-release theophylline preparation. The pharmacokinetics of erdosteine and theophylline were also studied. We found that a 2 week treatment with erdosteine (300 mg 3 times daily) was able to reduce significantly (p less than 0.05) the sputum apparent viscosity, fucose content, and macromolecular dry weight (MDW) with no statistically significant influence on sputum elasticity, DNA, albumin, total proteins, total IgA, lactoferrin, and lysozyme content. The treatment caused a significant increase in the following ratios: total IgA/albumin, lactoferrin/albumin, and lysozyme/albumin. The pharmacokinetics of erdosteine, its metabolites, and theophylline were the same after 1 or 14 days of treatment, evidence both of absence of an enzymatic induction and of an accumulation process. Further confirmation that there was no interference between erdosteine and theophylline was obtained from the data available on the group of patients receiving only theophylline, since its plasma levels and related pharmacokinetic parameters were identical to those obtained in patients receiving both drugs. In conclusion, 2 weeks of therapy with erdosteine reduced the marker of mucus glycoproteins (fucose) in patients with chronic bronchitis but did not interfere with the pharmacokinetics of xanthine derivatives. We also suggest that the significant increment in the IgA/albumin ratio might be related to a sum of other local effects such as reduction of the inflammatory process and enhancement of the humoral defense mechanism.

A new six-drug antiblastic regimen (R 14) at low doses (micropolychemotherapy) compared to CMF in the treatment of metastatic breast cancer: phase III study.

Two groups of 23 patients each, having advanced breast cancer, entered this prospective and randomized study. One group was treated with the conventional schedule of CMF (cyclophosphamide 100 mg/m2/po from the first to the 14th day, methotrexate 40 mg/m2/iv the first and the 8th day, 5-fluorouracil 600 mg/m2/iv the first and the 8th day), and the other was treated with a new six-drug regimen, administered at low doses (R 14: cyclophosphamide 2 mg/kg/iv, vincristine 0.01 mg/kg/iv, vinblastine 0.1 mg/kg/iv, the first day and 5-fluorouracil 5 mg/kg/iv, methotrexate 0.7 mg/kg/iv, adriamycin 0.5 mg/kg/iv the 2nd day every 21 days). The remission rate was 35% (8/23) and 39% (9/23) for CMF and R 14 respectively. The median duration of objective remission was 6 months for CMF and 5 months for R 14 regimen. The median survival time of responding patients was 18 months for CMF and 14 months for R 14. This study shows that the new six-drug regimen at low doses is effective (regarding subjective, objective response and survival rate), and its toxicity is no higher than that of CMF (the incidence of leukopenia was significantly lower during the first course). Therefore, R 14 should be considered an alternative regimen to CMF in the treatment of advanced and, possibly, early breast cancer. The advantages for using R 14 are: 1) it is less toxic (a single dose is a very small amount of medicine compared to what is usually administered), 2) an iv administration always follows a therapeutic program (while in a CMF schedule cyclophosphamide is self-administered by the patient).

Study of the hemocoagulative parameters in hemoperfusion on polymer coated resins.

A hemoperfusion column containing anionic exchange resin coated with a new polymer has been tested in vivo for blood compatibility. The hemocoagulative parameters, evaluated before and after the cartridge during hemoperfusion, did not show any significant alteration even as regards the number and the functionality of the platelets nor as regards a possible activation of the fibrinolysis process. On the basis of these results, the hemoperfusion system examined can be regarded as hemocompatible from the hemocoagulative standpoint.