Forage Quality of Cool Season Pasture Species Under Two Rotational Grazing Height Regimes

To optimize animal and pasture performance in management intensive grazing systems, pasture production and quality often must be compromised. Rotationally-stocking pastures at slightly taller grazing heights can increase pasture productivity, but lower forage quality may limit animal performance. Our objective was to compare the forage quality of common cool season pasture species in the Northeastern U.S., under two rotational grazing regimes defined by slightly different grass heights

Effects of initial grazing date on forage production and quality of a pasture in the Veneto plain. First year results

Agro-environmental measures in the current Common Agricultural Policy encourage the adoption of low-input agricultural practices that would reduce the impact of farming on the environment. In a mixed sward of the Veneto plain, we studied forage production and quality of a pasture that did not receive any fertilizer and irrigation input during the trial......

On new aspects of biological activity of some psoralen derivatives

The mechanism of the biological activity in the dark of some psoralen analogues waqs investigated. Psoralen derivatives resemble the behaviour of camptothecin, a specific inhibitor of topo I, but other topoisomerases could be also affected

Preparation and properties of monomethoxy poly(ethylene glycol)-doxorubicin conjugates linked by an amino acid or peptide as spacer

Polymeric doxorubicin prodrugs were prepared linking monomethoxy poly(ethylene glycol), 5000 D molecular weight, to the doxorubicin amino group, using an amino acid or a peptide as a spacer arm. As spacers glycine, Lphenylalanine, L-tryptophan and glycil-L-valil-L-phenylalanine were used. The conjugates showed enhanced stability to alkaline degradation compared to the free doxorubicin. Towards Ehrlich solid tumor in mice the glycin spaced derivative was devoid of activity, whereas the phenylalanine and tryptophan derivatives were 20% and 16% active and the tripeptide one 50% active with respect to free doxorubicin. On the other hand the derivatization was accompanied by a great decrease of toxicity in mice with respect to the free drug. Doxorubicin was not released from conjugates by chymotrypsin incubation or in plasm

New benzopsoralen derivatives: T2 phage inactivation.

The inactivation by a number of benzo and tetrahydrobenzopsoralen derivatives has been studied both by UVA irradiation and by simple incubation in the dark. Upon UVA irradiation the most active compounds appeared to be the 4-hydroxymethyl derivatives. After 3 hours of incubation in the dark all derivatives affected T2 infectivity. This dark effect could be related to a damage to the sensitive phage receptors necessary for its absorption on the bacterial surface

PHOTOBIOLOGICAL ACTIVITY OF CERTAIN NEW METHYLAZAPSORALENS

The photobiological activity of a series of psoralen isosters carrying a nitrogen atom at 8 position, new potential drugs for the photochemotherapy of hyperproliferative skin diseases, have been studied; the more active derivatives appeared to be 5,4'-dimethyl-8-azapsoralen and 3,4,4'-trimethyl-8-azapsoralen which induced a strong inhibition of DNA synthesis in Ehrlich ascites cells, very similar to that provoked by 8-methoxypsoralen, the furocoumarin at present used in photochemotherapy. Such compounds induced a small amount of inter-strand DNA cross-links and were non phototoxic when assayed on guinea-pig skin; however, both derivatives appeared to be highly mutagenic in E. coli WP2 TM6. This strain contains the plasmid R46 and it is proficient in DNA repair, and therefore monoadducts do not should be mutagenic in such a strain. Because the first steps of excision, which remove monoadducts, and of the main cross-link repair use the same enzymes (produced by the uvrABC complex), in the presence of a great number of monofunctional lesions, it is possible that there are not sufficient enzyme molecules for removing cross-links according this pathway, which could be repaired by a second one, uvrABC independent and based on glycosilase activity, which works at reduced levels and is much less accurate

In vitro and in vivo behaviour of narciclasine released from matrices based on poly (2-hydroxyethyl methacrylate).

Narciclasine (1,2,3,7-tetrahydroxy-8,9-methylendioxy-1,2,3,4-tetrahydrophena ntridone) is a natural substance with strong antimitotic effects on cells and potential antitumor activity. Its release form a hydrogel matrix was studied with the purpose of avoiding the concentration spikes of the parenteral administration. The matrix prepared by gamma ray polymerization of a mixture of 2-hydroxyethyl methacrylate (85%) and trimethylolpropane trimethacrylate (15%) was found to release narciclasine for several days, according to a diffusion controlled mechanism. In agreement with its antimitotic effect, narciclasine inhibited the growth rate of healthy mice, when the drug-loaded matrix was introduced subcutaneously. Antitumor effect was observed in an experimental model of Erlich ascitic tumor when low amounts of tumor cells were inoculated. No effect was observed at high concentrations of inoculum or towards solid tumors (Sarcoma 180). This behaviour was related to the rapid clearance of narciclasine from the body which prevented the reaching of sufficient therapeutical concentrations. A pharmacokinetic investigation carried out by an original method of assay demonstrated that narciclasine was accumulated in significant amounts in the kidney only and eliminated in urine with a half time of less than 20 mi