How to survive on Mediterranean coastal cliffs: tolerance to seawater in early life-cycle stages in Brassica incana Ten. (Brassicaceae).

Mediterranean coastal cliffs are reservoirs of plant biodiversity, hosting vulnerable plant species particularly exposed to the risk of local extinction due to extreme abiotic conditions and climate changes. Therefore, studies aiming to understand the tolerance of cliff plant species to abiotic stresses are important to predict their long-time persistence or to highlight inherent threats. We used an integrative approach including anatomical, physiological and phenotypic analyses on (a) seeds, (b) cotyledons of seedlings; and (c) young plants to assess whether the cliff species Brassica incana, can tolerate exposure to different seawater (SW: 25%, 50% and 100%) concentrations during the early stages of its life cycle. Seeds could germinate when exposed to up to 50% SW. Seeds did not germinate in 100% SW, but could resume germination after washing with freshwater. Seed germination rate also decreased with increasing SW concentration. Exposure to SW decreased stomatal size and stomatal index of cotyledons and caused long-lasting and severe damage to the photochemical reactions of photosynthesis. Photochemistry was also sensitive to SW in young plants, but the effect was lower than in cotyledons. This may involve a remodulation of chloroplast dimensions and activation of cellular metabolism. However, photochemical reactions limited photosynthesis at100% SW even after recovery from SW exposure. Our data show that B. incana has strong tolerance to seawater and shows clear signs of halophytic adaptation. Whilst seeds and juvenile plants are able to withstand SW, the seedling stage appears to be more sensitive.

Potential antitumor agents. 24. Synthesis and pharmacological behavior of imidazo[2,1-b]thiazole guanylhydrazones bearing at least one chlorine.

In connection with a previous research dealing with the antitumor activity of imidazo[2,1-b]-thiazole guanylhydrazones, this paper reports the synthesis of new derivatives which were tested for antitumor and positive inotropic activity. In most cases the cytotoxic data from the in vitro experiments (HeLa) were in agreement with the antitumor data in vivo (Ehrlich). The active compounds bear a phenyl ring at the 6 position. On the other hand, the most active cardiotonic agents were devoid of the phenyl ring.

H2 antagonists and therapy of rodent tumours.

Cimetidine and the latest H2 antagonist ranitidine administered with varying procedures did not give evidence of any antitumour activity.

Enhancement of mitogenic stimuli by phosphatidylinositol.

Phosphatidylinositol added to the medium markedly stimulated the growth-promoting effect of mitogens in normal cells (human lymphocytes and mouse embryo fibroblasts). However, it did not significantly affect quiescent cells or proliferating tumor cell lines (HeLa and MCF-7). The results are consistent with the suggested role of phosphatidylinositol in the widespread mechanism of calcium mobilization.

Anthracyclines cardiotoxicity: antagonism by sulmazole, a new cardiotonic agent.

In attempts to alleviate or prevent anthracyclines toxicity, we have recently reported that amrinone markedly reduced the negative inotropic effect of adriamycin in isolated guinea pig atria, in normodynamic or hypodynamic conditions (medium with reduced calcium content). Previous experiments on isolated guinea pig atria showed that the negative inotropic action of anthracyclic compounds was enhanced in hypodynamic conditions. The present study reports the effects of 4-epiadriamycin on spontaneously beating guinea pig atria, in normo- or hypodynamic conditions. 4-Epiadriamycin (100 micrograms/ml) exerts a negative inotropic and chronotropic effect which matches that of adriamycin. The negative effects of the two antitumoral drugs are antagonized by sulmazole, a benzimidazole derivative with cardiotonic activity. In contrast to cardiac glycosides, the new compounds (amrinone, sulmazole, and derivatives) could be experimented in an attempt to antagonize the toxicity of anthracyclic compounds.

Reduction of anthracycline cardiotoxicity by amrinone and sulmazole.

In attempts to alleviate or prevent anthracycline toxicity, we have recently reported that amrinone and sulmazole markedly reduce the negative inotropic effect of adriamycin and 4-epiadriamycin in isolated spontaneously beating guinea pig atria in normodynamic or hypodynamic conditions. Amrinone and sulmazole are non catecholamine, non glycoside agents with inotropic properties. The present study reports the effects of adriamycin and 4-epiadriamycin (100 micrograms/ml) on electrically driven isolated guinea pig left atrium in normodynamic or hypodynamic conditions. Exposure for 60' to the two drugs caused a depression of contractile force and of maximal rate of contractile force (df/dt). The cardiac depressant effect of adriamycin as shown previously on spontaneously beating atria does not differ from that of 4-epiadriamycin. The negative effects of the two antitumor drugs are antagonized by amrinone (200 micrograms/ml) and sulmazole (100 micrograms/ml).

Effect of adriamycin on myocardial contractility and on the action of antibiotic ionophores.

In the isolated guinea pig atria adriamycin exerted a negative inotropic effect; calcium ionophores A23187 and X537A increased the force of contraction. In the presence of adriamycin only the positive inotropic effect of ionophore A23187 was significantly reduced. It may be deduced that adriamycin shows its negative inotropic effect by inhibiting the entry of extracellular Ca++ into the myocardial cells and the release of Ca++ from intracellular stores.

Reduction of 4-epiadriamycin cardiotoxicity by milrinone, a new cardiotonic agent.

Recently, several non-catecholamine, non-glycoside cardiotonic drugs have been described. New compounds include amrinone, sulmazole and milrinone. Milrinone, a close analogue of amrinone, is about 30 times more potent than amrinone. In attempts to alleviate anthracyclines toxicity, we have previously reported that amrinone and sulmazole reduced the negative inotropic effect of adriamycin and 4-epiadriamycin in isolated guinea pig atria. The present study reports the effects of 4-epiadriamycin on electrically driven isolated guinea pig left atrium, in normodynamic or hypodynamic conditions. Exposure for 60' to 4-epiadriamycin (100 micrograms/ml) caused a depression of contractile force and of maximal rate of contractile force (df/dt). The negative effects of 4-epiadriamycin are antagonized by milrinone at 20 micrograms/ml.

Sensitivity to anthracyclines in P388/dx leukaemia cells.

It has been demonstrated previously that neoplastic cells with reduced oxygen consumption are more sensitive to doxorubicin8. We have examined the relationship between doxorubicin sensitivity and oxygen consumption of P388 murine leukaemia cell line (P388) and of a doxorubicin resistant subline (P388/dx). Oxygen utilization by P388/dx cells was higher than that found in the sensitive line. A variety of calcium antagonists, including channel blockers and intracellular antagonists (verapamil, trifluoperazine, dantrolene, TMB-8, nitrendipine) or membrane acting drugs (lucensomycin), enhanced the cytotoxic activity of doxorubicin in P388 and markedly in P388/dx subline. This action was accompanied by a reduction of oxygen consumption more pronounced in the resistant cells. These findings emphasizé the correlation between oxygen uptake, instead of calcium dependent processes, and doxorubicin responsiveness. The calcium ionophores A 23187 failed to alter doxorubicin activity in P388 and P388/dx leukaemia.

Synthesis and cytotoxic activity of a new alkylating derivative of dipyridamole.

Synthesis of 2,6-Bis[bis(2-chloroethyl) amino]-4,8-dipiperidinopyrimido[5,4-d] pyrimidine, a derivative of dipyridamole, was carried out by treating dipyridamole with thionyl chloride. Cytotoxic activity of this compound was assessed using cultured P388 leukaemia cells and HeLa cells. The compound inhibited the colony-forming ability of HeLa cells and showed a cytotoxicity on P388 cells comparable to that of other alkylating drugs (chlorambucil and CCNU).

Reduction of adriamycin cardiotoxicity by a new cardiotonic agent.

Recently several non catecholamine, non glycoside cardiotonic drugs have been described. New compounds include amrinone, sulmazole, milrinone and pimobendan. In an attempt to alleviate anthracycline toxicity, we have previously reported that these compounds reduced the negative inotropic effect of adriamycin, 4-epiadriamycin and esorubicin in isolated guinea pig atria. The present study reports the effects of a new cardiotonic agent synthesized and studied by us: 2,3-Dihydro-6- (2,5-dimethoxyphenyl) imidazo [2,1-b]thiazole (VA-5), the most active of a series of 32 compounds with imidazo [2,1-b] thiazole and thiazoline moiety. Exposure for 60 to adriamycin (100 micrograms/ml) of electrically driven isolated guinea pig left atrium, in normodynamic or hypodynamic conditions, caused a depression of contractile force and of maximal rate of contractile force (df/dt). The negative effects of adriamycin are antagonized by VA-5 (100 micrograms/ml).

The bactericidal effect on Pseudomonas strains of adriamycin associated with quinolones.

The in vitro antibacterial activity of quinolone compounds was assessed on strains of Pseudomonas aeruginosa isolated from clinical infections. The bactericidal effect of quinolones was high and their respective antibacterial properties with adriamycin remained unimpaired on strains both sensitive and resistant to betalactam and aminoglycoside antibiotics. The cytotoxic effect of the combination of adriamycin and quinolones was determined in cultured P388 leukemia cells: no interference with the cytotoxic activity of adriamycin was observed.

New alkylating agents: butyrophenone derivatives.

The antimitotic properties associated with the bis (2-chloroethyl) amino group are well known, a number of compounds bearing this group being of therapeutic interest. The choice of a suitable supporting moiety for this group is important. Our experiments on a butyrophenone derivative, ketocaine, which possesses local anesthetic activity, showed that this drug is able to modify the oxygen consumption by tissues with prevailing anaerobic metabolism and to inhibit the mitotic activity of human lymphocytes in culture stimulated by phytohemagglutinin. These observations prompted us to prepare compounds by the general formula reported in Tables I and II. All compounds were tested in mice implanted i.p. with 10(6) Ehrlich ascites tumour cells. After 24 h the animals were treated with a single dose of the compound. The antitumor activity was correlated with: position (2, 4) and length (n = 0-2) of the chain with carbonyl group; presence (R' = H, ND2) and position (2, 4) of nitro group; monofunzional or bifunzional compound. Some of these show a potent antitumor activity.

In vitro and in vivo studies with anionic sulfatide-liposomes containing adriamycin.

Neutral and negatively charged liposomes containing Adriamycin (ADM) were examined for efficiency of drug entrapment and stability in serum. The greatest entrapment of ADM was obtained with negatively charged liposomes containing sulfatide. Moreover, these sulfatide-containing liposomes were more stable than other liposomes in the presence of serum. Tissue distribution studies indicated that the levels of ADM were increased several-fold in mouse liver and spleen after i.v. injection of the drug entrapped in sulfatide-liposomes, while levels of the drug were significantly diminished in the heart. Finally, the in vivo antitumor activity of ADM in liposomes containing sulfatides resulted in significantly greater survival rates than free ADM or ADM entrapped in liposomes without sulfatides.

Antibacterial and cytotoxic effect of ceftazidime-mitoxantrone association.

Microbial infections are a major problem in tumor-bearing and in immunocompromised patients. In such conditions it is of paramount importance to know the possible interactions between anti-tumor and antimicrobial drugs. In the present work we investigated the relationship between Ceftazidime and Mitoxantrone. Ceftazidime and Mitoxantrone were tested alone and in combination for antibacterial activity against different strains of Gram- and Gram+ bacteria. The cytotoxic effect of combination Mitoxantrone-Ceftazidime was determined in cultured P388 leukemia cells. No interference with the antibacterial activity of Ceftazidime or with the cytotoxic activity of Mitoxantrone was observed.

Synthesis and cytotoxic activity of peptides containing basic amino acids residues.

We synthesized eight peptides containing from three to twenty residues of arginine, lysine and histidine, using an automated synthetiser and Fmoc strategy. All peptides were purified by preparative reverse-phase HPLC and characterized by electrospay mass spectometry. Cytotoxic activity was assessed on HeLa cells. One peptide inhibited the colony-forming ability of tumor cells.

Enhancement of cytotoxic activity by synthesis of peptide multimeric forms.

Synthesis of four multimeric H-Lys-His-His-Arg-Lys-Lys-His-Arg-Lys-Arg-Lys-His-His-Lys-Arg-Lys-oH peptides containing two, four, eight and sixteen branches was carried out by solid phase utilizing a lysine core matrix. These multimeric peptides enhanced activity by inhibiting the colony-forming ability of HeLa cells, from twenty-four to fifty-six times in comparison with the monomeric form. Unexpectedly the peptide with only two-branched sequences showed the highest inhibitory activity.

Reduction of adriamycin cardiotoxicity by enoximone.

Several non catecholamine, non glycoside cardiotonic drugs have been described recently. New compounds include amrinone, sulmazole, milrinone and pimobendan. In an attempt to alleviate or prevent anthracycline toxicity, we have reported that these compounds reduce the negative effects of adriamycin, 4-epiadriamycin and esorubicin in isolated guinea pig atria. The present study reports the effects of a new cardiotonic agent: enoximone. Enoximone was administered after adriamycin (100 micrograms/ml) on the isolated and spontaneously beating atria, and on electrically driven left atria of guinea pig-in normodynamic and hypodynamic conditions. Exposure for 60 minutes to the antitumor drug causes a depression of contractile force (g) and its derivative versus time (dF/dt, as maximal rate of contractile force). The negative effects of adriamycin are antagonised by enoximone (100, 200 micrograms/ml).

Antitumor activity of an alkylating derivative of dipyridamole.

Synthesis of 2,6-Bis[bis(2-chloroethyl)amino]-4,8-dipiperidino-pyrimido [5,4-d]pyrimidine (DIP-C1) was carried out, and the new derivative showed cytotoxic activity comparable to other alkylating drugs on cultured P388 leukaemia cells and HeLa cells. The present paper reports the effects of DIP-C1 on respiration of Ehrlich ascites tumor cells and on survival of the mice implanted with Ehrlich ascites tumor cells. The compound showed a significant activity in both experimental models.

Cytotoxic activity of aryl and heteroaroxylazoxy derivatives.

Synthesis of aryl and heteroarylazocyanides, azoxyesters and azoxysulphones, was carried out by the action of appropriate reagents on the corresponding nitroso derivatives and arylazoxyamides were obtained by hydrolysis of the corresponding azoxycyanides. Cytotoxic activity was assessed utilizing cultured P388 leukemia cells. Most of the compounds tested showed a marked cytotoxicity at concentrations below 1 micrograms/ml.