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At least 811 records · Page 45Linked to original sources
PubMed1977

Artificial sweeteners and human bladder cancer.

A positive association between the use of artificial sweetners, particularly saccharin, and risk of bladder cancer in males has been observed in a case-control study of 480 men and 152 women in three Provinces in Canada. The risk ratio for ever versus never used is 1-6 for males (P=0-009, one-tailed test), and a significant dose-response relationship was obtained for both duration and frequency of use. The population attributable risk for males is estimated at 7%, though for diabetics, who have a similar risk ratio for artificial sweetner use as non-diabetics, the attributable risk is 33%.

British Columbia↗
PubMed2001

Pharmacological evidence for complex and multiple site interaction of CXCR4 with SDF-1alpha: implications for development of selective CXCR4 antagonists.

The C-X-C chemokine SDF-1 and its receptor CXCR4, mediate a pivotal role in the pathophysiology of HIV-1 infection and vascular inflammatory diseases. In this study, we investigated the pharmacological properties of SDF-1alpha interaction with CXCR4 in human leukemia cell lines. Our data, based on [125I]-SDF-1alpha radioligand binding, SDF-1alpha-induced [35S]-GTPgammaS binding and use of specific CXCR4 antagonist AMD3100 reveals the complex nature of SDF-1alpha-CXCR4 interaction. Firstly, homologous competition with cold SDF-1alpha revealed a bimodal ligand displacement curve and secondly, although AMD3100 inhibited both SDF-1alpha-mediated chemotaxis (IC(50)=4.7 nM) and [35S]-GTPgammaS binding (IC(50)=7.4 nM) with high affinity, it was intriguingly up to 3000-fold less potent (IC(50)=15.2 microM) in the radioligand binding assay. These results provide pharmacological evidence for the recently described two-site model for SDF-1alpha-CXCR4 interaction. Accordingly, inhibition of SDF-1alpha binding to one of the receptor sites is sufficient to antagonize function, without causing its complete displacement from the receptor. Furthermore, these findings have important implications in the development and evaluation of CXCR4-selective small molecule antagonists for therapeutic use.

Benzylamines↗
PubMed2003

Establishment of an in vitro assay system mimicking human immunodeficiency virus type 1-induced neural cell death and evaluation of inhibitors thereof.

Human immunodeficiency virus type 1 (HIV-1)-associated central nervous system disorders, including encephalopathy, often occur in the late stage of HIV-1 infection. Some inflammatory cytokines and HIV-1 antigens released from infected microglia or brain macrophages are considered to play an important role in neuropathogenesis. In this study, an in vitro assay system has been established for the evaluation of neural cell death, which would be predictive of the pathogenesis of neural cell death in vivo. The human neuroblastoma cell line SK-N-SH was differentiated to a neural phenotype with retinoic acid, while the promyelocytic cell line HL-60 and its HIV-1-infected clone OM-10.1 were differentiated to macrophages with phorbol myristate acetate. When neural (differentiated SK-N-SH) cells were cocultured with either uninfected or HIV-1-infected macrophages (differentiated HL-60 or OM-10.1 cells, respectively) for 3-5 days, significant neural cell death was observed in the cells cocultured with infected macrophages. Direct contact with macrophages was not necessary for the induction of neural cell death, since indirect coculture or coculture supernatants could also induce neural cell death. Large amounts of cytokines and chemokines were released in the coculture supernatants. The CXCR4 antagonist AMD3100 and the HIV-1 transcription inhibitor K-37 partially inhibited neural cell death. These results indicate that this system seems to be a useful tool for the evaluation of compounds against HIV-1-induced neural cell death.

AIDS-Associated Nephropathy↗
PubMed1997

Bicyclams, a class of potent anti-HIV agents, are targeted at the HIV coreceptor fusin/CXCR-4.

Bicyclams are a novel class of antiviral compounds which are highly potent and selective inhibitors of the replication of HIV-1 and HIV-2. The prototype compound, AMD3100, has an IC50 of 1-10 ng/ml, which is a least 100,000 fold lower than the cytotoxic concentration. AMD3100 does not inhibit virus binding to the CD4 receptor and based on time-of-addition experiments, has been assumed to interact with the HIV fusion-uncoating process. Resistance of HIV-1 strains to AMD3100 is associated with the accumulation of several mutations in the viral envelope glycoprotein gp120. Here, we demonstrate that AMD3100 interacts with fusin (CXCR-4), the coreceptor used by T-tropic viruses to infect the target cells. The replication of NL4-3 wild type virus and NL4-3 dextran sulfate-resistant virus was inhibited by the CXC-chemokine, stromal cell-derived factor 1 (SDF-1), the natural ligand for CXCR-4. In contrast, the replication of the HIV-1 NL4-3 AMD3100-resistant virus was no longer inhibited by SDF-1. The bicyclams are the first low-molecular-weight anti-HIV agents shown to interact with the coreceptor for T-tropic viruses.

Anti-HIV Agents↗
PubMed1999

In vitro release of 5-fluorouracil with cyclic core dendritic polymer.

This paper describes the first synthesis of a series of dendritic polymers with a core of 1,4,7,10-tetraazacyclododecane. This core was allowed to react with methyl acrylate through a Michael addition and was then amidated with ethylenediamine. Repeating the two steps led to controlled molecular weight increasing and branching on the molecular level and produced four direction poly(amide-amine) dendrimers. We successfully synthesized dendrimers from generation 0. 5 to generation 5.5. Each generation was analyzed by Fourier- transform infrared (FT-IR) spectroscopy, 1H NMR and elemental analysis. Titrimetry was also used to determine the number of -NH2 of each full generation (2.0, 3.0, 4.0, 5.0). SEC (size exclusion chromatography) was performed to test the purity of G-3.0, G-4.0 and G-5.0. Parts of the outer layer -NH2 groups of the dendrimers generation 4 and generation 5 were acylated by acetic anhydride. The solubility in water of the dendrimer was thus greatly enhanced. The acetylated dendrimers were then reacted with 1-bromoacetyl-5-fluorouracil to form dendrimer-5FU conjugates. Hydrolysis of the conjugates in a phosphate buffer solution (pH 7.4) at 37 degreesC will release free 5FU. Different generation of dendrimer-5FU conjugates exert marking influence on the amount of 5FU released. The dendritic polymer seems to be a promising carrier for the controlled release of antitumor drugs.

Antimetabolites, Antineoplastic↗
PubMed1999

Evaluation of the potential of ion pair formation to improve the oral absorption of two potent antiviral compounds, AMD3100 and PMPA.

9-(2-phosphonyomethoxypropyl)adenine (PMPA) and AMD3100 are highly potent and selective antiretroviral agents. Since PMPA is negatively charged and AMD3100 positively charged at physiological pH, their transepithelial transport and their potential for oral drug delivery is very low. In this study, ion pair formation was evaluated as a possible strategy to enhance transepithelial transport of PMPA and AMD3100. Positively charged counter ions such as t-hexyl-, t-heptyl-, t-octylammonium bromide and dodecyl-, tetradecyl-, hexadecyltrimethylammonium bromide were used to form ion pairs with PMPA, while sodium taurodeoxycholate (in vitro experiments) and sodium taurocholate (in vivo experiments) were used as counter ions for AMD3100. The effect of counter ions on transepithelial transport of PMPA (1 mM) and AMD3100 (1 mM) was investigated by measuring the flux across Caco-2 monolayers. An enhancement in drug transport could be observed at a concentration of 2 mM of hexadecyltrimethylammonium bromide (counter ion for PMPA) and 10 mM of sodium taurodeoxycholate (counter ion for AMD3100), but at the concentrations used, the absorption enhancing effect could be attributed to a reduction of the integrity of the monolayers. When AMD3100 transport was tested at a concentration of 200 microM, no flux was observed, even in the presence of relatively high concentrations of counter ion (20 times the concentration of AMD3100). Results obtained from partitioning studies of the drugs in the presence or absence of counter ion revealed that competition by other ions was responsible for the absence of an effect: when pure water was used as the aqueous phase, a reduction up to 24.4+/-1.4% and 17.0+/-1.3% of the initial aqueous concentration was observed for PMPA and AMD3100, respectively; however, as soon as other ions were present in the aqueous phase, the effect of the counter ion was diminished (25-50 mOsm) or completely abolished (270-305 mOsm). The absorption enhancing effect of counter ions was also studied in vivo: pharmacokinetic studies in rabbits showed that the oral bioavailability of AMD3100 in the presence of 4 equivalents of taurocholic acid remained very low and was only 3.2-fold better (i.e. 3.6%) in comparison to pure AMD3100. In view of the results obtained in the Caco-2 system, this absorption enhancement can be attributed to an effect on monolayer integrity rather than to the potential to form ion pairs. We can conclude that the formation of ion pairs may not be very efficient as a strategy to enhance transepithelial transport of charged hydrophilic compounds, as competition by other ions may abolish the beneficial effect of counter ions.

Adenine↗
PubMed2001

Hamao Umezawa Memorial Award Lecture: "An Odyssey in the Viral Chemotherapy Field".

In the search of effective and selective chemotherapeutic agents for the treatment of viral infections, my "Odyssey" brought me to explore a variety of approaches, encompassing interferon and interferon inducers, suramin and other polyanionic substances, S-adenosylhomocysteine hydrolase inhibitors, inosine 5'-monophosphate dehydrogenase inhibitors, 5-substituted 2'-deoxyuridines such as (E)-5-(2-bromovinyl)-2'-deoxyuridine, acyclovir (esters) and other acyclic guanosine analogues, 2',3'-dideoxynucleoside analogues, non-nucleoside reverse transcriptase inhibitors (NNRTIs), bicyclams, and acyclic nucleoside phosphonates. This had led to the identification of a number of compounds, efficacious against such important viral pathogens as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), and other herpesviruses, pox-, adeno-, polyoma-, and papillomaviruses, and hemorrhagic fever viruses.

Antiviral Agents↗
PubMed2001

Hydrolysis of plasmid DNA catalyzed by Co(III) complex of cyclen attached to polystyrene.

Reactivity of the Co(III) complex of cyclen (CoCyc) in the hydrolytic cleavage of supercoiled pUC18 DNA leading to the formation of the corresponding open circular form was enhanced by >200 times upon attachment of CoCyc to cross-linked polystyrenes. Thus, half-lives as short as 40 min were achieved by the resin-based CoCyc in cleavage of the supercoiled DNA at 4 degrees C.

Cobalt↗
PubMedDate not supplied

AMD3100 conjugates as components of targeted nonviral gene delivery systems: synthesis and in vitro transfection efficiency of CXCR4-expressing cells.

We describe the synthesis of a series of AMD3100-lipid and AMD3100-polycationic conjugates which were used as components of targeted lipoplexes (in conjunction with (poly)cationic lipids) and polyplexes, respectively, for mediating specific gene transfer into cells expressing CXCR4 which displays a high affinity for AMD3100. Transfection studies were investigated with suspension CXCR4(+) human lymphoma Jurkat cells and with adherent CXCR4(-) human glioblastoma T98G and human lung carcinoma A549 cells lines in order to demonstrate a receptor-mediated endocytosis pathway and to minimize nonspecific transfection pathways. Altogether, our results show that polyplexes formulated with AMD-labeled polymers constitute, under certain conditions, specific gene transfer systems into suspension CXCR4(+) Jurkat cells. This is more particularly the case when the nonspecific transfection pathways are minimized (i.e. for N/P <or= 2.5 AMD-labeled polyplexes) and in the presence of phorbol myristate acetate which triggers CXCR4 receptor endocytosis of the AMD-labeled polyplexes to a larger extent than that of their respective nonlabeled ones. Although encouraging, the transfection specificities and efficiencies obtained with these compounds should however be improved. This study also illustrates the difficulties to demonstrate and to obtain a specific and efficient gene transfer system with cationized ligand-labeled DNA particles which also provide receptor-independent nonspecific gene transfer to cells, and more particularly to adherent cells.

Benzylamines↗
PubMedDate not supplied

Cyclen-based phenylboronate ligands and their Eu3+ complexes for sensing glucose by MRI.

Novel cyclen-based phenylboronate ligands and their corresponding Eu(3+) complexes have been examined as glucose sensors using chemical exchange saturation transfer (CEST) MR imaging for detection. Two isomeric bis-phenylboronate complexes, Eu(4) and Eu(10), and a mono-phenylboronate complex, Eu(12), had been prepared and characterized by UV and circular dichroism spectroscopy, mass spectrometry, and CEST imaging. Both the free ligands and their Eu(3+) complexes bind to simple sugars, but their selectivity and binding affinities vary with sugar structure. Interestingly, the free ligands, 4 and 10, are selective for fructose over glucose, but this selectivity order switches in the respective Eu(3+) complexes. Of the complexes examined, Eu(4) shows the highest selectivity and binding affinity for glucose (2275 +/- 266 M(-)(1) at pH 10.2 and 339 +/- 29 M(-)(1) at pH 7). Glucose acts as a "capping"moiety in the Eu(4).glucose binary complex and modulates water exchange between a single Eu(3+)-bound water molecule and bulk water, an effect that can be detected by CEST imaging. Thus, Eu(4) represents a new class of metabolite-specific imaging agents that may allow mapping of metabolites by MRI of the bulk water signal.

Boronic Acids↗