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At least 865 records · Page 48Linked to original sources
PubMed2004

Carboxylic acid functionalized cobalt(III) cyclen complexes for catalytic hydrolysis of phosphodiester bonds.

4-(1,4,7,10-Tetraazacyclotetradec-1-yl)methylbenzoic acid (cycmba, 1) has been synthesized, as a step towards the eventual development of sequence-specific hydrolytic complexes. A cobalt(III) complex of 1, [Co(cycmba)Cl2]Cl.1.5H2O (.1.5H2O) was found to be active against both an activated phosphodiester compound, bis(nitrophenyl)phosphate (BNPP), and supercoiled DNA. The presence of the benzoate group depresses the rate of hydrolysis of the ligand-Co(III) system at neutral pH, as confirmed by the kinetics results of a methyl ester analog. The ability of (2.1.5H2O) to bind to solid substrates and remain active was also demonstrated by attachment of the molecule to agarose beads.

Carboxylic Acids↗
PubMed2005

Responsive lanthanide luminescent cyclen complexes: from switching/sensing to supramolecular architectures.

This article highlights some of the recent developments in the use of responsive cyclen based lanthanide luminescent devices, focusing on Eu(III), Tb(III), Nd(III) and Yb(III) complexes, where the photophysical properties, such as the excited state lifetimes, quantum yield/intensity and emission polarisation are modulated by the local chemical environment, e.g. ions and molecules, or through self-assembly of either f-f or mixed f-d cyclen complexes.

Crystallography, X-Ray↗
PubMed2005

Visual sensing of Ca2+ ion via photoreaction of fluorenyl ester-armed cyclen.

Fluorenyl ester-armed cyclen gave fluorenone and related decomposition compounds upon photoirradiation. The reaction was effectively suppressed by the formation of an octacoordinated Ca2+ complex while Na+ and other alkali/alkaline earth metal cations had little influence. Since the production efficiency of fluorescent fluorenone related well to the concentration of the Ca2+ ion, the photoreaction of this armed cyclen offered the naked-eye detection of Ca2+ ion in aqueous samples.

Calcium↗
PubMed2005

Cyclen based bis-macrocyclic ligands as phosphates receptors. A potentiometric and NMR study.

The host-guest interaction between orthophosphate, pyrophosphate and triphosphate anions and four cyclen based bis-macrocycles ligands possessing ortho-(BOC), meta-(BMC), para-xylenyl (BPC) or 2,6-pyridinyl (BPyC) linker was investigated by potentiometric measurements and NMR spectroscopy. Each ligand gave protonated species in aqueous solution that further formed ternary complexes after binding with anions; these complexes were analyzed as a result of hydrogen bond formation and Coulombic attraction between the organic host and the inorganic guest. The equilibrium constants for all the detected species are reported and the selectivity, illustrated with species distribution diagrams, is discussed. The results unambiguously showed the importance of the distance between the two cyclen cores and underlined, especially for the triphosphate species, the contribution of the nitrogen atom of the pyridinyl spacer as a supplementary anchoring point in acidic medium.

Anions↗
PubMed2005

Towards the rational design of MRI contrast agents: a practical approach to the synthesis of gadolinium complexes that exhibit optimal water exchange.

The gadolinium(iii) complex of S-SSSS-NO(2)BnDOTMA exhibits water exchange kinetics that are optimal for use in high relaxivity or targeted contrast agents. However, the synthesis of this ligand is hampered by the steric encumbrance imparted upon the cyclen ring by the nitrobenzyl substituent. A relatively simple modification has been used to enable the synthesis of larger quantities of a bifunctional ligand that retains similar fast water exchange properties. The gadolinium complex of S-SSS-NO(2)BnDO3MA-1A is shown to retain the rapid water exchange kinetics characteristic of a twisted square antiprismatic (TSAP) coordination geometry (tau(M)= 6 +/- 0.4 ns).

Alkylating Agents↗
PubMed2006

Synthesis and characterisation of bis-cyclen based dinuclear lanthanide complexes.

The design and synthesis of several bis-macrocyclic cyclen (1,4,7,10-tetraazacyclododecane) ligands and their corresponding lanthanum or europium complexes is described; these dinuclear lanthanide systems were made by connecting two macrocyclic cyclen moieties through a rigid, covalent, p-xylylenediamide bridge or a flexible aliphatic hexane bridge. These ligands were subsequently functionalised with six acetamide pendant arms (CONR1R2: R1 = R2 = H or CH3, or R1 = H, R2 = CH3). The corresponding lanthanide bis-complexes were then formed by reaction with La(III) and Eu(III) triflates, yielding overall cationic (+VI charged) complexes.

Cyclams↗
PubMed2006

Host-guest interaction between cyclen based macrotricyclic ligands and phosphate anions. A potentiometric investigation.

The host-guest interaction between orthophosphate, pyrophosphate and triphosphate anions and three cyclen based macrotricyclic ligands possessing ortho- (TOC), meta- (TMC) and para-xylenyl (TPC) linkers was investigated by potentiometric measurements. The ternary species present in solution and their stability constants have been determined. The different behaviours are explained in terms of hydrogen bond formation and coulombic attraction between the organic host and the inorganic guest. The selectivity, illustrated with species distribution diagrams, is discussed. The results unambiguously showed the importance of the distance between the two cyclen cores and emphasized the increasing of the triphosphate species selectivity together with the cavity size of the ligand. A comparison of the present results with those obtained with their mono-bridged homologues is also discussed.

Anions↗
PubMed1976

[Differences in taste assessment of sweeteners by normal and overweight persons].

Taste assessment was tested in 20 obese and 20 normal-weight in-patients using watery solutions of saccharose and three synthetic sweeteners. Each patient was asked to assess ten different taste qualities of each solution on a point scale. There were highly significant differences between the two groups of subjects. The difference was especially marked for the categories "synthetic - natural", "unpleasant - very tasty", and "changeable - stable in times". These findings suggest changes in physical or central taste sensation in obese persons. This view is supported by their decreased ability to differentiate between saccharose and any sweetener. The results further support substituting sweetening agents for sugar in reducing diets.

Adult↗
PubMed1999

[Crystalline keratopathy as a presenting sign of multiple myeloma].

BACKGROUND: Noninfectious crystalline corneal degenerations can be classified from the clinical and genetical point of view into 3 groups: 1. primary hereditary (Schnyder), 2. secondary hereditary (cystinosis) and 3. secondary non-hereditary in association with disorders of serum protein or lipid composition. PATIENT: We report on a 63-year-old man with reduced vision and grey-white, crystalline, monomorpheous deposits in the corneal stroma. Further investigation revealed IgG myeloma. RESULTS: We performed a penetrating keratoplasty for visual improvement. On histopathological examination, typical eosinophilic, PAS-positive, interlamellar deposits staining brilliant red with Masson's trichrome were found diffusely scattered throughout the stroma. Electron microscopy showed intracellular, rhomboid-shaped deposits enveloped by a membrane. CONCLUSION: The appearance of a crystalline keratopathy should be followed by an internal examination for early detection and adequate treatment of a systemic disease.

Antineoplastic Agents, Hormonal↗
PubMedDate not supplied

[Abuse of artificial sweetener as differential diagnosis of lactose intolerance].

A two year old dystrophic boy with chronic diarrhea was described. At the age of 6 month the boy developed a severe gastroenteritis with a secundary lactase deficiency. Dietary treatment was however not successful and consequently the boy became dystrophic. At last, an abuse of sweetener was diagnosed.

Child, Preschool↗
PubMed1980

Artificial sweeteners and cancer of the lower urinary tract.

We evaluated the relation between cancer of the lower urinary tract and the use of artificial sweeteners in a case-control study of 592 patients with lower-urinary-tract cancer (94 per cent of whom had a bladder tumor) and 536 controls chosen from the general population of the study area. A history of use or artificial sweeteners and exposure to other known or suspected risk factors was determined by interview. In those who had used dietetic beverages and in those who had used sugar substitutes, the relative risk of lower-urinary-tract cancer was estimated as 0.9 (0.7 to 1.2, 95 per cent confidence interval), as compared with 1 in nonusers of artificial sweeteners. Among men, the relative risk was 0.8 (0.6 to 1.1) in those who had used dietetic beverages and 0.8 (0.5 to 1.1) in those who had used sugar substitutes. Among women, the corresponding relative risks were 1.6 (0.9 to 2.7) and 1.5 (0.9 to 2.6). Increasing frequency of duration of use of artificial sweeteners was not consistently associated with increasing relative risk. This study suggests that, as a group, users of artificial sweeteners have little or no excess risks of cancer of the lower urinary tract.

Adult↗
PubMed2003

R5 HIV productively infects Langerhans cells, and infection levels are regulated by compound CCR5 polymorphisms.

Langerhans cells (LCs) are suspected to be initial targets for HIV after sexual exposure (by becoming infected or by capturing virus). Here, productive R5 HIV infection of LC ex vivo and LC-mediated transmission of virus to CD4+ T cells were both found to depend on CCR5. By contrast, infection of monocyte-derived dendritic cells and transfer of infection from monocyte-derived dendritic cells to CD4+ T cells were mediated by CCR5-dependent as well as DC-specific ICAM-3-grabbing nonintegrin-dependent pathways. Furthermore, in 62 healthy individuals, R5 HIV infection levels in LCs ex vivo were associated with CCR5 genotype. Specifically, genotyping for ORF Delta 32 revealed that LCs isolated from ORF Delta 32/wt individuals were significantly less susceptible to HIV when compared with LCs isolated from ORFwt/wt individuals (P = 0.016). Strikingly, further genetic analyses of the A-2459G CCR5 promoter polymorphism in ORF Delta 32/wt heterozygous individuals revealed that LCs isolated from -2459A/G + ORF Delta 32/wt individuals were markedly less susceptible to HIV than were LCs from -2459A/A + ORF Delta 32/wt individuals (P = 0.012). Interestingly, these genetic susceptibility data in LCs parallel those of genetic susceptibility studies performed in cohorts of HIV-infected individuals. Thus, we suggest that CCR5-mediated infection of LCs, and not capture of virus by LCs, provides a biologic basis for understanding certain aspects of host genetic susceptibility to initial HIV infection.

Antibodies, Monoclonal↗
PubMed2003

A small-molecule antagonist of CXCR4 inhibits intracranial growth of primary brain tumors.

The vast majority of brain tumors in adults exhibit glial characteristics. Brain tumors in children are diverse: Many have neuronal characteristics, whereas others have glial features. Here we show that activation of the Gi protein-coupled receptor CXCR4 is critical for the growth of both malignant neuronal and glial tumors. Systemic administration of CXCR4 antagonist AMD 3100 inhibits growth of intracranial glioblastoma and medulloblastoma xenografts by increasing apoptosis and decreasing the proliferation of tumor cells. This reflects the ability of AMD 3100 to reduce the activation of extracellular signal-regulated kinases 1 and 2 and Akt, all of which are pathways downstream of CXCR4 that promote survival, proliferation, and migration. These studies (i) demonstrate that CXCR4 is critical to the progression of diverse brain malignances and (ii) provide a scientific rationale for clinical evaluation of AMD 3100 in treating both adults and children with malignant brain tumors.

Animals↗
PubMed2001

Novel low molecular weight spirodiketopiperazine derivatives potently inhibit R5 HIV-1 infection through their antagonistic effects on CCR5.

Novel low molecular weight spirodiketopiperazine derivatives which potently inhibit R5 human immunodeficiency virus type 1 (HIV-1) infection through their antagonistic effects on CCR5 were identified. One such compound E913 (M(r) 484) specifically blocked the binding of macrophage inflammatory protein-1alpha (MIP-1alpha) to CCR5 (IC(50) 0.002 microm) and MIP-1alpha-elicited cellular Ca(2+) mobilization (IC(50) approximately 0.02 microm). E913 potently inhibited the replication of laboratory and primary R5 HIV-1 strains as well as various multidrug-resistant monocyte/macrophage tropic (R5) HIV-1 at IC(50) values of 0.03 to 0.06 microm. E913 was inactive against T cell tropic (X4) HIV-1; however, when combined with a CXCR4 antagonist AMD-3100, E913 potently and synergistically inhibited the replication of dualtropic HIV-1 and a 50:50 mixture of R5 and X4 HIV-1. Antagonism in anti-HIV-1 activity was not seen when E913 was combined with the reverse transcriptase inhibitor zidovudine or protease inhibitors. E913 proved to compete with the binding of antibodies to CCR5 which recognize the C-terminal half of the second extracellular loop (ECL2B) of CCR5. E913 and its analogs are acid-resistant and orally bioavailable in rodents. These data warrant that spirodiketopiperazine derivatives be further developed as potential therapeutics for HIV-1 infection.

Animals↗