Publications

A series of cyclic and acyclic nucleoside analogues derived from 3-hydroxy-4-pyridinone were synthesized using the Vorbrüggen reaction. Iron chelation studies, and antiviral evaluation against a broad panel of viruses, were performed. The pK(a) value of ligand 25 and the stability constant of the corresponding iron(III) complex were compared to those of deferiprone. The pFe(3+) values were found to be similar. Some compounds showed moderate activity against both wild-type HSV-1 and HSV-2, as well as against a thymidine kinase deficient strain of HSV-1. These results suggest a novel mode of action for this group of nucleoside analogues.

(+)- Trans-(5R,6R)-5-bromo-5-ethyl-6-ethoxy-5,6-dihydro-5′-O-valeryl-2′-deoxyuridine (3) and (+)- trans-(5R,6R)-5-bromo-5-ethyl-6-ethoxy-5,6-dihydro-3′,5′-di-O-valery[-2′-deoxyuridine (4) were synthesized in 55% and 8.6% yield, respectively, by esterification of the 5′-hydroxyl group of (+)- trans-(5R,6R)-5-bromo-5-ethyl-6-ethoxy-5,6-dihydro-2′-deoxyuridine (2) using valeryl chloride. [4- 14 C]-3 and [4- 14 C]-4 were synthesized in 79% and 64% chemical and radiochemical yield, respectively, by similar esterifications of [4- 14 C]-2. The double prodrug 3 was readily hydrolysed (> 95% in 8 min) to 5-ethyl-2′-deoxyuridine (EDU) by porcine liver esterase in vitro. The biotransformations of 2 and 3 were studied following i.v. injection of a 0.4 mmol/kg i.v. dose to male Balb/c mice. The single prodrug 2 was rapidly cleared (<10 min) from the blood. The area under the blood concentration-time curve (AUC) for EDU, as a metabolite of 2, was higher (2.1 ± 0.4 μmol.h.g −1 ) than the AUC observed when EDU itself was injected (1.7 ± 0.2 μmol.h.g −1 ). The double prodrug 3 provided a sustained high concentration of EDU in blood, with an AUC for EDU, as a metabolite of 3, of 1.8 ± 0.2 μmol.hr.g −1 . 5′-O-Valeryl-5-ethyl-2′-deoxyuridine and 3 were both detected in blood samples collected up to 35 min post i.v. injection. 5-Ethyluracil and 5-(1-hydroxyethyl)-uracil were identified as secondary metabolites of EDU, 2 and 3. Compared to [4- 14 C]-EDU, i.v. injection of [4- 14 C]-3 or [4- 14 C]-4 provided significantly higher (P < 0.001) radioactivity levels in the brain, but neither EDU, 2 or 3 protected mice against intracerebral herpes simplex virus infection. Hepatic uptakes of 2, 3 and 4, in mice, were similar to each other despite the respective substantial increases in both molecular weight and lipophilicity of this series. In rats, biliary excretion over the 0-4 h period after i.v. injection accounted for only 2.9-3.9% of the injected dose for these prodrugs.

The first TSAO derivative that lacks the amino group at the 3'-spiro moiety has been prepared. This molecule retained its HIV-1 specificity (NNRTI characteristic) but did not select for any of the classical NNRTI-specific mutations in the NNRTI binding pocket, including 138-Lys (TSAO resistant strain).

The efficacy of 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (S2242) was evaluated in several animal models for herpesvirus infections. Compound S2242 was more effective than acyclovir (i) when administered subcutaneously in a model for herpes simplex virus type 1 (HSV-1)-induced mortality in immunocompetent mice and (ii) when applied topically to hairless (hr/hr) mice that had been infected intracutaneously with HSV-2. In SCID (severe combined immune deficient) mice that had been infected with a thymidine kinase-deficient HSV-1 strain, S2242 (administered subcutaneously at a dosage of 50 mg/kg/day) completely protected against virus-induced mortality whereas foscarnet was less effective and acyclovir had no or little protective effect. Compound S2242 was far more effective than ganciclovir in preventing or delaying murine cytomegalovirus-induced mortality in immunocompetent and SCID mice. The compound was more effective when a given dose was fractionated and administered on subsequent days than when this dose was administered in one single injection. A 5-day treatment course with S2242 (10 and 50 mg/kg/day) for newborn mice that had been infected with a lethal dose of murine cytomegalovirus suppressed virus-induced mortality. Compound S2242 had no inhibitory effect on the growth of weanling (at 50 mg/kg for 5 days) and 3- to 4-week-old mice (at doses of 50 to 200 mg/kg for 6 weeks). However, akin to ganciclovir, compound S2242 significantly reduced testicle weight, testicle morphology, and spermatogenesis.

Multinucleated giant cell (syncytium) formation induced by the interaction between the gpl20 glycoprotein expressed on the surface of cells infected with human immunodeficiency virus type 1 (HIV-1) and the CD4 receptor of uninfected CD4-positive (CD4+ ) cells may play an important role in the depletion of T4 lymphocytes in acquired immune deficiency syndrome (AIDS) patients. Using a double fluorescence cell-staining technique and analysis of the cells by the fluorescence-activated cell sorter (FACS), we have demonstrated that giant cell formation between persistently HIV-1-infected HUT-78 cells and uninfected MOLT-4 cells results in a selective destruction of the uninfected CD4+ MOLT-4 cells. Apparently, bystander CD4+ cells may serve as targets for the killing effect of the HIV-1-infected cells, and this killing effect is preceded by fusion between the target (uninfected) and aggressor (infected) cells. Pentosan polysulfate, dextran sulfate, and various other sulfated polysaccharides, but not heparin, have proved to inhibit this cell fusion process and hence protect the target CD4+ cells against destruction by the killer HIV-1-infected cells. Azidothymidine does not interfere with this process. Assuming that fusion between HIV-infected and uninfected CD4+ cells is a crucial event in the pathogenesis of AIDS, any compounds that specifically interfere with this process may be therapeutically advantageous in the treatment of this disease.

Polyomavirus infections in humans are due to BK virus (BKV) and JC virus (JCV). Diseases associated with human polyomaviruses occur mostly in immunocompromised adults, e.g., progressive multifocal leukoencephalopathy (PML), caused by JCV, in AIDS patients and hemorrhagic cystitis and uretral stenosis, caused by BKV, in transplant recipients. No therapy is available for these diseases, which necessitates the development of chemical entities that are active against polyomaviruses. Several antiviral compounds were evaluated to determine their effects on the in vitro replication of mouse polyomavirus and the primate viruses simian virus 40 (SV40), SV40 PML-1, and SV40 PML-2. The activity of the different compounds was assessed by a cytopathic effect reduction assay and confirmed in a virus yield assay. Cidofovir [HPMPC; (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine] and its cyclic counterpart emerged as the most selective antipolyomavirus agents. The 50% inhibitory concentrations for HPMPC were in the range of 4 to 7 micrograms/ml, and its selectivity index varied from 11 to 20 for mouse polyomavirus and from 23 to 33 for SV40 strains in confluent cell monolayers. Cell cytotoxicity was up to 15-fold greater in growing cells. Other acyclic nucleoside phosphonates (i.e., HPMPA; [(S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine] and PMEG [9-(2-phosphonylmethoxyethyl)-guanine]) also showed some activity but had low selectivity. None of the other drugs tested against these animal viruses (i.e., acyclovir, ganciclovir, brivudine, ribavirin, foscarnet, and cytarabine) showed significant activity. Thus, HPMPC deserves further evaluation as a candidate drug for polyomavirus infections in the immunocompromised host.

With the introduction of computed tomography (CT) for purpose of dimensional quality control, the problem has arisen of identifying the measurement uncertainty of CT-based length measurements. This paper presents a conceptual framework for CT measurement uncertainty based on the ISO-GUM, starting from the product of the voxel size and the number of voxels as the description of every CT measurement. Those two main uncertainty contributors are further subdivided and illustrated based on various measurements. Finally, this paper shows how a measurement procedure, based on voxel size and edge correction can eliminate some terms of the total uncertainty budget.

Abstract For Abstract see ChemInform Abstract in Full Text.

For the first time, an N4-amino derivative of 1,2,4,6-thiahiazine 1.1dioxide (5) was prepared by cyclocondensation reaction of the appropriate sulfamoylcarbamate (3) with hydrazine.Reaction of 3 with ammonia yielded the cyclic 4H-derivative (4j.Nucleophilic substitution reactions of 4 and 5 with hydrazine, as well as condensation of 5 with ethyl orthoformate were achieved.The antiprotozoal and anti-HIV properties of the new compounds were evaluated, but none of them showed significant biological activities.