Iron (III) stimulation of lipid hydroperoxide-dependent lipid peroxidation.

In an experimental system where both Fe2+ autoxidation and generation of reactive oxygen species is negligible, the effect of FeCl2 and FeCl3 on the peroxidation of phosphatidylcholine (PC) liposomes containing different amounts of lipid hydroperoxides (LOOH) was studied; Fe2+ oxidation, oxygen consumption and oxidation index of the liposomes were measured. No peroxidation was observed at variable FeCl2/FeCl3 ratio when PC liposomes deprived of LOOH by triphenylphosphine treatment were utilized. By contrast, LOOH containing liposomes were peroxidized by FeCl2. The FeCl2 concentration at which Fe2+ oxidation was maximal, defined as critical Fe2+ concentration [Fe2+]*, depended on the LOOH concentration and not on the amount of PC liposomes in the assay. The LOOH-dependent lipid peroxidation was stimulated by FeCl3 addition; the oxidized form of the metal increased the average length of radical chains, shifted to higher values the [Fe2+]* and shortened the latent period. The iron chelator KSCN exerted effects opposite to those exerted by FeCl3 addition. The experimental data obtained indicate the kinetics of LOOH-dependent lipid peroxidation depends on the Fe2+/Fe3+ ratio at each moment during the time course of lipid peroxidation. The results confirm that exogenously added FeCl3 does not affect the LOOH-independent but the LOOH-dependent lipid peroxidation; and suggest that the Fe3+ endogenously generated exerts a major role in the control of the LOOH-dependent lipid peroxidation.

Effects of taurine and hypotaurine on lipid peroxidation.

It has been suggested that hypotaurine might inhibit lipid peroxidation in vivo by scavenging the initiator OH. The results presented demonstrate that hypotaurine affects other reactions relevant to the initiation, propagation and termination phases of lipid peroxidation. Hypotaurine a) decreases Fe2+ autoxidation, either spontaneous or catalyzed by Fe3+, that may generate perferryl iron; b) decreases Fe2+ oxidation, by cumene hydroperoxide, that forms the alkoxy radical; c) inhibits the lipid hydroperoxide dependent lipid peroxidation, favoring the onset of the termination phase. Hypotaurine does not affect the autoxidation of Fe2+ bound to phosphatidic acid containing liposomes. Taurine is ineffective in all the experimental systems tested.

[Intermediate medications in endodontics: a quantitative in-vitro evaluation of 2 phenolic derivatives]. / Medicazioni intermedie in endodonzia: valutazione quantitativa in vitro di due derivati fenolici.

In a series of in vitro experiments with dental elements obtained after an extraction, the persistence in the pulpal chamber of two phenolic compounds largely used as dental medicaments has been evaluated. The substances, p-chlorophenol and eugenol were put in a small piece of cotton inside the dental elements where they were left for 7 days. Spectrophotometric UV determination of p-chlorophenol and eugenol were made after 3 and 7 days. Our results indicate that 25% of the initial amount of p-chlorophenol is found after three days and nearly 1/5 after 7 days. The figures for eugenol are: 1/3 after three days and 1/6 of the initial amount after 7 days. The authors therefore suggest the substances under study be used as dental medicaments with an optimum of three days of interval between two medications, even if a longer interval may be observed due to the good in situ persistence of the two phenols.

Evaluation of opioid peptide gene expression by solution hybridization RNase protection.

The solution hybridization RNase protection assay may be considered a suitable method for both qualitative and quantitative analysis of mRNAs. In the present study we described an application of solution hybridization RNase protection assay to the quantitative analysis of prodynorphin mRNA, which encodes for the synthesis of prodynorphin, a common precursor for a number of opioid peptides. In the myocardial cell, stimulation of the K opioid is involved in the modulation of cytosolic calcium and pH homeostasis. In the present study, we found that prodynorphin mRNA, which encodes for the synthesis of a common precursor of opioid peptides interacting with K sites, is synthesized both in atrial and in ventricular tissue of the rat heart. In adult cultured rat ventricular cardiomyocytes, the level of prodynorphin mRNA did not differ from that detected in the original ventricular tissue. This finding indicates that the myocardial cell is an important source for prodynorphin gene expression and has the potential for an intrinsic synthesis of dynorphin-related peptides.

Polyamine levels during the onset of "CAM" inOpuntia F. indica (Miller).

Polyamines have been related to the "Crassulacean Acid Metabolism" (CAM) in higher plants. Such relationship was however observed in plants where CAM activity is inducible by external factors. Results presented here indicate that, inOpuntia F. indica, cladodes where onset of CAM is dependent on internal conditions, i.e. leaf age, the concentration of putrescine increases in parallel to the acidity of the cytoplasm. The parallel increase of putrescine concentration and acidity (malic acid concentration) can be best evaluated during the onset of CAM (young cladodes), while such correlation is not observed in mature cladodes where CAM is already in it's full function. Spermidine and spermine show no correlation with CAM activity neither during the onset of CAM nor during it's full function. However, spermidine levels correlate negatively to CAM activity when cladodes attain > 30 days of age. The results suggest that putrescine in free form could possibly counteract the increase of cellular acidity during onset of CAM inOpuntia F. indica; the possible roles of spermidine are discussed.

[Peptidase activity and toxicity of strains of Pseudomonas aeruginosa]. / Attività peptidasiche e tossicità in ceppi di Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a microorganism of the terrestrial and aquatic environment which may cause pulmonary, urinary and corneal infections. The pathogenesis of Pseudomonas-induced diseases seems to be linked to the production of extracellular substances such as exotoxins, hemolysins, leukocidins and hydrolytic enzymes, including various peptidases. Anyway there is not a clear view on the role other proteases have in the mechanism of pathogenesis, and even if their activity may always be associated to the toxicity of the microorganism. We have therefore determined the activity of a number of eso- and endopeptidases in 17 strains of P. aeruginosa isolated from patients with urinary pathologies. Four of these peptidase activities, namely elastase, neutral protease, aminopeptidase I and leucine aminopeptidase show a positive correlation with three parameters selected as indices of toxicity, i.e. the mucoid appearance, the gentamicin resistance and the adhesivity of colonies.

[Metabolism of ornithine in human gingival tissue]. / Metabolismo dell'ornitina in tessuto gengivale umano.

The behavior of two enzymes of the ornithine pathway, leading to the formation of proline and, eventually, of collagen, arginase and ornithine oxo-acid aminotransferase has been investigated in normal and inflamed gingival tissue. Both enzymatic activities show a statistically significant decrease in pathological samples as compared to normal ones. The data on arginase activity may be in agreement with the already documented low level of urea in pathological gingival fluid, while a decrease of the ornithine aminotransferase activity could be linked to the phenomenon of gingival retraction, i.e. the lack of complete regeneration of gingival tissue usually observed in chronically inflamed subjects, that would be reasonably parallel to a decreased proline/collagen synthesis.

[Arginase characteristics in an ammoniotele]. / Caratteristiche dell'arginasi di un organismo ammoniotelico.

Arginase (EC 3.5.3.1.) is active in the hepatopancreas, gills and pincer muscle of the ammoniotele Carcinus maenas. Its activity in the hepatopancreas is mainly localized in mitochondria. The enzyme becomes inactive at 37 degrees C if the assay is carried out without previous incubation with Mn2+; the optimum temperature for the fully activated enzyme is 47 degrees C. Two fractions showing arginase activity can be separated on DEAE-cellulose at pH 8.3, the most active being eluted by a linear gradient of KCl at a concentration of 0.3 divided by 0.4M, the other with a buffer front. Since ornithine transaminase (EC 2.6.1.13.) activity has been detected in the hepatopancreas, arginase activity in this organ is possibly related to ornithine catabolism leading to proline and glutamate.

Carbamylphosphate hydrolysis in donkey liver.

Mitochondria, microsomes, and cytosol all hydrolyze carbamylphosphate. Microsomes show the greatest specific activity. The mitochondrial enzyme is localized in the inner membranes, has optimum pH 5.5 and is heat-stable; the cytosol enzyme has optimum pH 5.0 and is heat-labile. Km for carbamylphosphate is 1.1 to 1.2 X 10(-2 M for both the cytosol and the mitochondrial enzyme. Both enzymes are inhibited by high substrate concentrations.