Effects of 2,2'-O-cyclocytidine and acyclovir on latent herpes simplex virus in trigeminal ganglia of mice.
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The effects of 2,2'-O-cyclocytidine (CC) and acyclovir (ACV) on latent herpes simplex virus (HSV) in trigeminal ganglia were studied in an in vitro model using reactivation of HSV type 1 (HSV-1) as a model. It was shown that both CC (10 micrograms/ml) and ACV (2.5 micrograms/ml) significantly inhibited the reactivation of the latent HSV-1 in infected ganglia. The effect of CC (25 micrograms/ml), which was as good as that of ACV (10 micrograms/ml), did not last as long as that of ACV after removal of the drugs. The latent state of HSV-1 in vitro was dependent on the continuous presence of either drug. Even though the latent HSV-1 could not be eliminated completely from the trigeminal ganglia by discontinuous administration of either drug, its titers were markedly reduced. The combination of CC and ACV had a synergistic effect on preventing the reactivation of the latent HSV-1 in vitro. (+info)
Antiviral activities of acyl derivatives of 2,2'-anhydro-1-beta-D-arabinofuranosylcytosine and 1-beta-D-arabinofuranosylcytosine in cell culture.
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Antiviral activities of acyl derivatives (3'-O-octanoyl and 3'-O-decanoyl) of 2,2'-anhydro-1-beta-d-arabinofuranosylcytosine (cyclo-C) and 1-beta-d-arabinofuranosylcytosine (Ara-C) were compared with other antiviral nucleosides, and some biological characteristics of the antiviral activity were investigated. Among those synthesized acyl derivatives, 3'-O-decanoyl ara-C was the most active against deoxyribonucleic acid viruses, with an activity comparable to that of Ara-C. Acyl derivatives of cyclo-C were somewhat less active than their Ara-C counterparts. In the value of therapeutic index, 1-beta-d-arabinofuranosyladenine was superior to the others, followed by 5-iodo-2'-deoxyuridine. In comparing the sensitivity of two serotypes of herpes simplex virus it was found that Ara-C and its ester, as well as its cyclo-C counterpart, were more active against the type 2 than the type 1 strain. The activity of 3'-O-decanoyl Ara-C, like that of its parent, was diminished by treatment with cytidine deaminase from mouse kidney, but 3'-O-decanoyl cyclo-C was resistant to this treatment. In comparative studies of 3'- and 5'-O-acyl Ara-C's, antivaccinia virus activity of 3'-O-palmitoyl Ara-C was significantly superior to its 5'-counterpart. The inhibitory activity of 5'-O-decanoyl Ara-C was markedly reduced by the presence of a threefold molar excess of eserine sulfate, a choline esterase inhibitor, whereas the 3'-acyl Ara-C was not affected by the inhibitor in any combination. This result indicates that enzymatic hydrolysis of the 3'-ester to Ara-C, which is inhibited by eserine sulfate, did not occur in this cell culture. (+info)
Synergistic effects of the combination of cis-platinum diamminodichloride and 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine in transplanted mouse leukemias.
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cis-Platinum diamminodichloride has been studied in combination with 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine on an every-4-day schedule in various lines of mouse leukemia. This combination is synergistic in leukemias L1210 and P388 and sublines made resistant to 5-fluorouracil or methotrexate. There is no cross-resistance between cis-platinum diamminodichloride and 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine, but the combination is no more effective against lines of leukemia made resistant to cis-platinum diamminodichloride or to 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine than either single active compound alone. Since these compounds have no cross-resistance, act by quite different mechanisms of action, and have different limiting toxicity, the combination is now being evaluated clinically. (+info)
Tyramine-like effect of cyclocytidine (2,2'-anhydro-1-beta-arabinofuranosylcytosine hydrochloride), an antineoplastic agent.
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Since cyclocytidine (2,2'-anhydro-1-beta-arabinofuranosylcytosine hydrochloride) was introduced as an antineoplastic agent for the treatment of lymphatic leukemia, sinus acceleration and an increase in systemic blood pressure has been reported as its systemic effects in the clinical cases. These cardiovascular effects of cyclocytidine were observed also in anesthetized dogs, but not in reserpine-pretreated animals. Increases in heart rate and in systemic blood pressure were prevented by propranolol and phentolamine, respectively. The mechanism of these sympathomimetic effects was further analysed in the excised, blood-perfused canine sinoatrial node and papillary muscle preparations with a support dog. Positive chronotropic and inotropic responses to cyclocytidine were abolished by desipramine, propanolol, and pretreatment with reserpine but not by tetrodotoxin and hexamethonium. The tyramine-like actions of cyclocytidine at adrenergic neuronal terminals were discussed in conjunction with the uptake mechanism of the drug into the tumor cells. (+info)