A comparison of the modulation of antiblastics cytotoxicity by verapamil and dipyridamole in a human colon carcinoma cell line.

This study was designed to compare the activity of two MDR modulators, verapamil and dipyridamole, on the in vitro growth of a human colon carcinoma cell line. The aims were: a) to investigate the different sensitivity of the parental cell line (LoVo S) and the doxorubicin-resistant one (LoVo R) towards the treatment with several antiblastics and their associations with verapamil or dipyridamole; b) to evaluate if the combined use of these drugs with verapamil or dipyridamole increases their cytotoxicity; c) to understand whether the mechanism of action of each modulator is the same. Idarubicin and vinblastine were the most active drugs on both cell lines. LoVo R cells showed cross-resistance to vinblastine, teniposide and mitoxantrone, while chemosensitivity towards cisplatin and cyclophosphamide was almost the same in both cell lines. The inhibitory effect on cell growth was enhanced when the drugs were associated with verapamil, but no difference was detected with cisplatin and cyclophosphamide. Verapamil is thus an effective MDR modulator when used with drugs actively pumped out of tumour cells by P-glycoprotein, while it is ineffective with drugs that induce resistance by different mechanisms. When combined with dipyridamole, a significant result was observed in the case of cisplatin, where a marked increase of cytotoxicity was detected.

A new place conditioning paradigm to study tolerance to opiates in mice.

Tolerance to the rewarding properties of morphine was investigated in mice using a new conditioned place preference (CPP) procedure. Four pairings of morphine with specific environmental cues induced a significant CPP for the drug-paired cues. Further opiate conditioning trials in the presence of the same environmental cues revealed no change in the drug-induced CPP on repeated test sessions. Subsequent exposure of the same animals to conditioning trials by pairing morphine with a set of novel environmental cues showed that the opiate was still able to produce a CPP in mice treated with a total of 16 morphine injections. The present CPP paradigm may prove useful to investigate tolerance to the rewarding properties of drugs of abuse.

In vitro effect of Pt and Pd mercaptopyridine complexes.

In previous research we studied the cytotoxic effect of new Pt mercaptopyridine (MP) complexes on several tumoral cell lines (F10, Föhn, LoVo and HeLa) as well as on the fibroblast cell line (3T3). The more interesting Pt compounds are compared here to Pd mercaptopyridine analogs, in order to evaluate the metals influence on activity. Earlier, the complexes C/2 = [Pt(MP)3Cl]Cl; C/5 = [Pt(MP)3Br]Br; C/8 = [Pd(MP)3Cl]Cl and C/11 = [Pd(MP)3Br]Br and cis-DDP as reference were tested on 3T3 and LoVo cells, by Sauter's multiwells technique and neutral red uptake. The results obtained using lysosomal neutral red uptake to confirm those by the Sauter's multiwells techniques, showing that C/2 and C/11 are the most active complexes. In particular, C/2 shows a significantly higher cytotoxic activity than cis-DDP on LoVo cells, and equivalent on 3T3. C/5 complex also induces an interesting cell growth reduction, but only on LoVo, while C/8 is completely inactive on all cell lines. Because the major limitation to the successful treatment of platinum-based chemotherapeutic regimens is the emergence of drug resistance, the activity of the four complexes on cis-DDP sensitive (M5076) and cis-DDP resistant cancer cells (M5/DDPc) has been tested. The data reported in this work make devident that the presence of ligands with sulfur donor atoms may be of particular importance in confirming the antitumor properties of Pt complexes. In fact, Pt mercaptopyridine C/2 is also more active than cis-DDP against cells made resistant to cis-DDP. Moreover, the results obtained with Pd complex C/11, especially on LoVo cells, showed that this metal could be considered interesting in the design of potential new antitumor drugs.

Influence of verapamil on tumour cell growth in vitro following treatment with antiblastic drugs.

The effect of antiblastic drugs with different mechanisms of action has been investigated in LoVo cells (on the resistant line LoVo R and the parental LoVo S) for 48 h and for further 24 h in drug-free medium (recovery time) in order to evaluate drug action after its removal. Our results show that the drug effect persists in time, particularly in LoVo R cells. The inhibitory effect on cell growth was enhanced when the drugs were associated with verapamil, while no difference was detected with cisplatin and 4-hydroperoxycyclophosphamide, drugs which are not involved in P-glycoprotein-mediated multidrug resistance. These results demonstrate that verapamil is an effective agent in association with those drugs which are actively transported out of the tumour cells, while it is ineffective on drugs which can induce resistance by different mechanisms.

Dipyridamole as a modulator of multidrug-resistance in tumor-cells in-vitro.

The aim of the present study was to investigate in vitro the effect on LoVo cells (LoVo-S, doxorubicin-sensitive, and LoVo-R, doxorubicin-resistant) on the association of dipyridamole and certain antiblastic drugs (doxorubicin, idarubicin, mitoxantrone, teniposide) with different mechanisms of action. The cells were treated for 48 hours with the drugs, or were left for 24 hours without treatment (recovery period). The results demonstrate that dipyridamole possesses an inhibitory effect on cell growth, and that it potentiates the cytotoxic effect of the tested antiblastic drugs, particularly on LoVo-R cells. In the recovery period the inhibitory effect of dipyridamole on LoVo-S and LoVo-R cells was reversible, while the effect of the antitumour drugs, either alone or in association with dipyridamole, persisted. We suggest that dipyridamole has a synergistic effect on LoVo cell growth when associated with antiblastics; the increased effect produced on LoVo-R cells is indicative for a reversion of multidrug resistance, probably via a mechanism related to transmembrane transport system.

Study on the bactericidal activity and synergistic effect of neutropenic rat serum with gentamicin.

It is well known that normal rat serum (NRS) shows an antibacterial activity because of the presence of endogenous substances that are able to express a defence against pathogenic microorganisms. Moreover, in former studies, we observed that NRS presents a synergistic activity with some antibiotics (thus able to lower minimum inhibitory concentration values). The aim of this research was to study the antibacterial activity and synergistic effect of neutropenic rat sera (NPRS) with gentamicin. The animals were made neutropenic by the i.p. injection of cyclophosphamide (100 mg/kg on day 0 and 75 mg on day 4). At all tested concentrations (from 0.25% to 5%) NPRS showed lower antibacterial activity than NRS with differences which were always statistically significant. The synergistic activity of NPRS with gentamicin was still present and quite similar to that of NRS, in spite of many altered blood parameters showing evident immunodepression. Some possible interpretations of these results are discussed.

[Interferon-alpha. Results of a pharmaco-epidemiologic study]. / Interferone alfa. Risultati di uno studio farmaco-epidemiologico.

In the present study we evaluated the use of alpha-IFN in the ULSS 21 of Veneto Region. All outpatients treated with interferon during the period June-July 1992 (114 subjects) were interviewed using a standard questionnaire which was meant to collect information about therapy, side effects and quality of life. Alpha-IFN was mostly prescribed for chronic non-A non-B hepatitis (as approved by the FDA in the USA and by the Ministero della Sanità in Italy), while 35% of the patients were suffering from diseases for which interferon use is approved by Ministero della Sanità but not by FDA. In most cases, independently of the specific disease, a standard dose of 9 MU/week was used, which often resulted to be below the recommended doses reported in the literature. Adverse effects were frequently reported. The most common include fever, chills, headache, fatigue, myalgia. Mild mental disturbances (irritability and/or depression) and thyroid dysfunction were also reported but were less frequent. Finally, a negative influence of alpha-IFN therapy on the quality of life was reported by about half of the interviewed patients.

Effect of dipyridamole, 5'-(N-ethyl)-carboxamidoadenosine and 1,3-dipropyl-8-(2-amino-4-chlorophenyl)-xanthine on LOVO cell growth and morphology.

The effects of stable compounds acting on adenosine receptors, 5'-(N-ethyl)-carboxamidoadenosine (NECA: A2 and A1 adenosine receptor agonist) and 1,3-dipropyl-8-(2-amino-4-chlorophenyl)-xanthine (PACPX: selective A1 adenosine receptor antagonist) were evaluated in vitro on doxorubicin-resistant LoVo (LoVo-R) and doxorubicin-sensitive LoVo (LoVo-S) human metastatic cell lines by using the neutral red test for cell growth. The effect of dipyridamole, an adenosine uptake inhibitor, was also evaluated. The drugs had an inhibitory effect on LoVo cell growth. The association of the drugs with doxorubicin enhanced the inhibition of cell growth, particularly for NECA and PACPX on LoVo-R cells. Morphological observation with scanning electron microscopy indicated cytotoxicity of the tested compounds, alone or in association with doxorubicin both in LoVo-R or LoVo-S cells, supporting the hypothesis of inhibitory effect on tumor cell growth.

The effect of cis-DDP and Pt mercaptopyridine complexes on cell lines in vitro.

The effect of Platinum (II) complexes with mercaptopyridines on cell lines (fibroblasts 3T3 and the tumour ones F10, Föhn, Lovo) were studied. Synthesis and characterization of the compounds are reported together with the preliminary in vitro tests. Data obtained on cytopathogenic effect (CPE), cell growth and colony forming ability demonstrated that all the platinum mercaptopyridines tested are more active than cisplatin in the same conditions.

Biocompatibility and biodegradation of different hyaluronan derivatives (Hyaff) implanted in rats.

Hyaluronan (HL), a naturally occurring glycosaminoglycan, has been chemically modified through the esterification of its carboxylic groups with different types of alcohol. The physico-chemical properties of these new biopolymers allow the preparation of many biomaterials which may be used in several medical applications. In the present study both the biocompatibility and biodegradation of some water-insoluble HL esters have been evaluated, either as raw material or as manufactured devices after subcutaneous and intraperitoneal implantation in male rats. The inflammatory response and the degree of resorption for each tested material are reported. The relationships between the degree of esterification and the type of alcohol used with the above parameters are also investigated.

Comparison of the antibacterial activity and synergistic activity towards antibiotics of different mammalian sera.

The antibacterial activity against Escherichia coli ATCC 10798 and Staphylococcus aureus Mag 90 of normal sera from nine species of mammals was investigated by Avantage (Abbott). Human and rat sera showed the highest antibacterial activity against E. coli ATCC 10798, while all investigated sera did not exhibit, till the maximum concentration tested (20%), spontaneous antibacterial activity against S. aureus Mag 90. Heat inactivated sera (56 degrees C for 30 min) of all investigated species lost their antibacterial activity, but maintained their synergistic effect with sub-MICs of some antibacterial drugs, principally against E. coli ATCC 10798.

Possible influence of assay methods in studies of the pharmacokinetics of antibiotics.

In the present research, levels of gentamicin (GM) in serum and carrageenan pleural exudate from the rat have been compared, using three evaluation methods: microbiological assay (MA), enzyme-immunoassay (EMIT) and fluorescence-immunoassay (TDX). In a first study, the evaluations carried out by MA and EMIT have furnished comparable data in serum, while statistically significant differences were verified at all times in pleural exudate. On the contrary, in a second study, while the evaluations carried out by MA and EMIT, at all times and in both biological fluids, have produced similar data, the evaluation carried out by TDX consistently supplied higher results, with statistically significant differences at some times (5 min and 60 min for serum, 30 min and 60 min for exudate). Some possible interpretations of these results are discussed.

Professional role of the clinical pharmacologist.

The position of clinical pharmacologists in the field of medicine is reviewed. In more than one-third of the medical schools in Europe, teaching of clinical pharmacology is inadequate or non-existent. The situation in Italy is even worse; there are, however, 18 schools of specialization in pharmacology in that country, covering four areas, clinical and applied pharmacology, toxicology and chemotherapy with the course lasting four years. In addition there are 13 hospitals at regional level which provide service in clinical pharmacology, though in most of these the clinical pharmacologist has no direct clinical responsibilities. Three basic requirements, accepted by the College of Italian Pharmacologists, are listed aimed at obtaining official recognition of the professional role of a physician specialized in clinical pharmacology.

Arginine 2-mercaptoethane sulfonate and sodium 2-mercaptoethane sulfonate: a comparative study of their effects upon tumour cells.

The action of arginine 2-mercaptoethane sulfonate in comparison with sodium 2-mercaptoethane sulfonate on cell growth and cell adhesion of a metastatic sub-line of murine melanoma (F10/B16) was investigated. The capability of the two compounds to interfere with the cytotoxicity of 4-hydroperoxycyclophosphamide and of cis-dichlorodiammineplatinum(II) in F10 cells was studied. The in vivo studies included the determination of acute and sub-acute toxicity of the two salts on mice. Very low toxicity and no significant differences between the two compounds were detected.

Enhancement of antibiotic antibacterial activity by experimental pleural exudates.

The aim of this research was to study the synergistic effect of experimental pleural exudates and antimicrobial drugs on various microorganisms. The antibacterial activity of different pleural exudates alone and in the presence of sub-MIC amounts of antibiotics was studied by a continuous recording turbidimetric method. Synergistic action between the antibiotics and the exudates was demonstrated. This phenomenon can be explained by the presence of heat-labile substances that themselves possess only slight antibacterial activity but are able to increase the effect of sub-MIC antibacterial drugs.

Effects of 6,6'-dithiodinicotinic acid (CPDS) and its metabolite 6-mercaptonicotinic acid (6-MNA) on murine and hamster fibroblasts (3T3 and BHK) and murine metastatic melanoma cells (F10).

We investigated the action of 6,6'-dithiodinicotinic acid (CPDS) and its metabolite 6-mercaptonicotinic acid (6-MNA) in vitro on murine (3T3) and baby hamster kidney (BHK) fibroblasts and an in vivo highly metastatic subline of murine B16 melanoma (F10). CPDS determined an inhibition of cell growth and a decrease in cell adhesion, while 6-MNA had no effect. When combined with data of the mitotic index and endogenous purine ribonucleotides (on which the drugs seem to have no effect), these observations are conceivable with the hypothesis that the primary target of CPDS is cell membrane.

Tissue distribution of methotrexate in rats. A comparison between intravenous injection as bolus or drip infusion.

Concentrations of methotrexate (MTX, 30 mg/kg) in rat sera and tissues were compared after the drug was administered by i.v. route as bolus injection or by drip infusion. Plasma and tissue specimens were collected after 1 h and 4 h and assayed for MTX by RIA. After 1 h the continuous infusion gave higher MTX levels in plasma, liver, bowel, lung, kidney, testicle and muscle; bolus injection gave higher levels in brain. No differences in levels were found in fat. After 4 h the differences between the two methods of administration were still appreciable only in liver, testicle and muscle. The differences were confirmed by determination of AUC for sera and tissue levels (1-4 h). These data suggest that continuous infusion may be more useful to obtain the highest levels of MTX in tissues with low or medium blood flow (as is probably the case in cancer tissue). Bolus injection, on the other hand, promotes the flow of the drug across the blood-brain barrier.