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PubMed2005

Preparation and preliminary biological evaluation of a (166)Ho labeled polyazamacrocycle for possible use as an intravascular brachytherapy (IVBT) agent.

(166)Ho can be considered as a potential radionuclide for intravascular brachytherapy (IVBT) using liquid-filled balloons owing to its suitable nuclear decay characteristics. The possibility of producing (166)Ho with adequate specific activity using moderate flux reactors and natural holmium target makes it an attractive alternative of (188)Re for developing IVBT agents. Keeping in mind the high thermodynamic stability of lanthanide complexes with polyazamacrocycles, (166)Ho complex of 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA) was prepared and studied for its suitability as a possible agent for IVBT. (166)Ho was produced with adequate specific activity and high radionuclidic purity by irradiating natural Ho(2)O(3) powder. TETA was synthesized by a single step procedure using cyclam as the starting material. (166)Ho-TETA complex was prepared with excellent radiochemical purity and the complex was found to retain its stability for 7 days at room temperature. Biodistribution studies carried out in Wistar rats showed major renal clearance of the injected activity with almost no retention in any of the vital organ/tissue.

Animals↗
PubMed2005

AMD3465, a monomacrocyclic CXCR4 antagonist and potent HIV entry inhibitor.

The chemokine receptors CCR5 and CXCR4 function as coreceptors for human immunodeficiency virus (HIV) and are attractive targets for the development of anti-HIV drugs. The most potent CXCR4 antagonists described until today are the bicyclams. The prototype compound, AMD3100, exhibits potent and selective anti-HIV activity against CXCR4-using (X4) viruses and showed antiviral efficacy in X4 HIV-1-infected persons in a phase II clinical trial. However, AMD3100 lacks oral bioavailability due to its high overall positive charge. Initial structure-activity relationship studies with bicyclam analogues suggested that the bis-macrocyclic structure was a prerequisite for anti-HIV activity. Now, we report that the N-pyridinylmethylene cyclam AMD3465, which lacks the structural constraints mentioned above, fully conserves all the biological properties of AMD3100. Like AMD3100, AMD3465 blocked the cell surface binding of both CXCL12 (the natural CXCR4 ligand), and the specific anti-CXCR4 monoclonal antibody 12G5. AMD3465 dose-dependently inhibited intracellular calcium signaling, chemotaxis, CXCR4 endocytosis and mitogen-activated protein kinase phosphorylation induced by CXCL12. Compared to the bicyclam AMD3100, AMD3465 was even 10-fold more effective as a CXCR4 antagonist, while showing no interaction whatsoever with CCR5. As expected, AMD3465 proved highly potent against X4 HIV strains (IC50: 1-10 nM), but completely failed to inhibit the replication of CCR5-using (R5) viruses. In conclusion, AMD3465 is a novel, monomacrocyclic anti-HIV agent that specifically blocks the interaction of HIV gp120 with CXCR4. Although oral bioavailability is not yet achieved, the monocyclams, with their decreased molecular charge as compared to the bicyclams, embody an important step forward in the design of oral CXCR4 antagonists that can be clinically used as anti-HIV drugs.

Anti-HIV Agents↗
PubMed2006

High-performance liquid chromatography-electronspray ionization mass spectrometry for determination of tiopronin in human plasma.

A simple and sensitive HPLC/ESI-MS method for the determination of tiopronin in human plasma was described. Vitamin C and 2-mercaptoethanol (2-Me) were used as the reducer and the stabilitizer to release and stabilify tiopronin from a dimmer and mix forms with endogenous thiols in the treatment of plasma samples. The analytes were separated on a Johnson Spherigel analytical column packed with 5 microm C8 silica, using the formic acid aqueous solution (pH 4.5) including tris(hydroxymethyl) aminomethane (Tris) and 2-Me (0.5 and 1 mM, respectively) as a mobile phase. Cyclamate was used as the internal standard (I.S.) for the quantification of tiopronin. The correlation coefficient of the calibration curve were better than 0.998 in the range of 0.107-5.35 microg/ml in human plasma. The limit of quantification (LOQ) was 0.107 microg/ml (S/N 10:1, RSD 7.1%). The inter-day and intra-day accuracy was below 7.1 and 6.8%, respectively. As a preliminary application, this method has been successfully applied to the determination of tiopronin in the human plasma.

Calibration↗
PubMed2004

Dietary estimated intake of intense sweeteners by Italian teenagers. Present levels and projections derived from the INRAN-RM-2001 food survey.

In a previous study, Italian female teenagers regular consumers of sugar free soft drinks and table-top sweeteners were suggested to have a higher intake of intense sweeteners than other teenagers. A food frequency questionnaire designed to identify adolescents who were high consumers of these food products was filled in by a randomly extracted sample of teenagers (n=3982) living in the District of Rome (Italy) in year 2000. A consumer survey was then carried out in a randomly extracted sub-sample of males and females and in all females who reported high consumption of sugar-free soft drinks and/or table-top sweeteners. A total of 362 subjects participated in a detailed food survey by recording, at brand level, all foods and beverages ingested over 12 days. For each sugar-free product, producers provided the concentration of intense sweeteners (saccharin, aspartame, acesulfame K and cyclamate). No intake in excess of the Acceptable Daily Intake (ADI) was observed. Also medicines and supplements were taken into account and these did not result in a large impact on chronic exposure to intense sweeteners. The intake levels did not exceed the ADI even under a worst case scenario which was performed to take into consideration a hypothetical future substitution of all regular food products with their sugar-free version. It can be concluded that, with the observed current consumption patterns and occurrence levels, the risk of an excessive intake of intense sweeteners by Italian teenagers is extremely low.

Adolescent↗
PubMed1987

Recovery of polypeptides after reversed-phase high-performance liquid chromatography.

Mass recovery of individual polypeptides may be estimated under various practical conditions. With the purpose of obtaining rapid and reliable standard procedures for recovery measurements, we have compared five individual methods utilizing a silica-based stationary phase [Nucleosil C18 (7 microns)/ammonium sulphate-perchlorate-acetonitrile, pH 3.0] and a resin-based stationary phase (TSK Phenyl 5 PW RP/ammonium phosphate-acetonitrile, pH 7.0). The recoveries of insulin (6 kilodaltons), human growth hormone (22 kilodaltons) and human serum albumin (68 kilodaltons) estimated under five different experimental conditions were found to be concordant. Variations in column load, flow-rate, gradient shape and column dwell time and addition of cyclame did not increase the (reduced) recovery of serum albumin and growth hormone.

Chromatography, High Pressure Liquid↗
PubMed1976

Non-nutritive sweeteners and human bladder cancer: preliminary findings.

The non-nutritive sweeteners, saccharin and cyclamate, were not associated with the risk of human bladder cancer in a controlled investigation. The prior intake of such sweeteners in any and all forms was not greater or more prolonged among 209 recently diagnosed bladder cancer patients than among 209 otherwise similar patients without bladder disease. These findings were unaffected by case-control differences in diabetic histories or smoking practices.

Animals↗
PubMed2000

Effect of temperature, pH, and ions on sweet taste.

The purpose of this experiment was to determine the effects of temperature (50 degrees C and 6 degrees C), pH (pH 3.0, 4.0, 5.0, 6. 0, and 7.0) and the addition of monovalent and divalent cations (5 mM Na(+), 5 mM K(+), and 5 mM Ca(2)+ ) on the sweetness intensity ratings of sweeteners ranging widely in chemical structure. A trained panel provided intensity evaluations for prototypical tastes (sweet, bitter, sour, and salty) as well as aromatic and mouth-feel attributes. The following sweeteners were included in this experiment: three sugars (fructose, glucose, sucrose), three terpenoid glycosides (monoammonium glycyrrhizinate, rebaudioside-A, stevioside), two polyhydric alcohols (mannitol, sorbitol), two dipeptide derivatives (alitame, aspartame), two N-sulfonylamides (acesulfame-K, sodium saccharin), one sulfamate (sodium cyclamate), one protein (thaumatin), one dihydrochalcone (neohesperidin dihydrochalcone), and one chlorodeoxysugar (sucralose). Two to five levels of each sweetener reflecting a range of sweetness intensities were tested, using formulae developed by DuBois et al. The main finding from this three-part study was that temperature, pH, and ions had little effect on perceived sweetness intensity. Even when significant differences were found in the temperature study, the effects were very small.

Calcium↗
PubMed1986

The role of non-nutritive dietary constituents in carcinogenesis.

Very low levels of a large variety of non-nutritive chemicals occur in the diet. Among those that occur naturally are metabolites of molds (for example, mycotoxins) and bacteria (for example, nitrosamines) and natural constituents of plants (for example, pyrrolizidine alkaloids). Many of these are occasional contaminants, whereas others are normal components of relatively common foods. Some compounds (for example, aflatoxin, nitrosamines, and hydrazones) have been found to be carcinogenic in laboratory animals and mutagenic in bacterial and other systems, thereby posing a potential risk to humans. However, there have been very few definitive epidemiologic studies. Therefore, further investigations are necessary to determine the significance of these experimental findings for humans. It is apparent that many foods naturally contain substances with mutagenic properties and that some substances found in foods can enhance or inhibit the mutagenic activity of other compounds. Furthermore, mutagens can be formed during the cooking or processing of foods. However, caution is needed in the interpretation of these findings. Although mutagens by definition are "suspect" carcinogens, many mutagens detected in foods have not been adequately tested for carcinogenicity, and therefore their significance for human health cannot be fully assessed. With the exception of studies on non-nutritive sweeteners like saccharin and cyclamate, or those on nitrate and nitrite, very few epidemiologic studies have been conducted to examine the effect of food additives on cancer risk. Of the few direct food additives that have been tested and found to be carcinogenic in animals, all except saccharin have been banned from use in the food supply. Minute residues of a few indirect additives that are known either to produce cancer in animals (for example, vinyl chloride and acrylonitrile) or to be carcinogenic in humans (for example, vinyl chloride) are occasionally detected in foods. Thus far, the increasing use of food additives does not seem to have contributed significantly to the overall cancer risk for humans. However, the relatively short duration of use of many of these substances and the inadequacy of the data base preclude definitive conclusions. Very low levels of a large and chemically diverse group of substances--environmental contaminants (for example, residues of pesticides, polycyclic aromatic hydrocarbons, and traces of toxic metals)--may be present in foods.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Vagotomy abolishes the differential palatability of food.

The magnitude of preabsorptive insulin release varies as a function of palatability. This suggests that the palatability-dependent rise in plasma insulin could accentuate the systemic stimulus to eat, which in turn could modulate the size of the meal. The present experiment was designed to test this hypothesis by investigating the ingestive responses of vagotomized rats, which no longer exhibit preabsorptive insulin release, when they are offered nutritionally identical diets differing only in their sensory characteristics. The presented foods were three forms of the rat's regular diet: unaltered, sweetened with sodium cyclamate or adulterated with quinine hydrochloride. It was shown that vagotomized rats ate exactly the same amount of the three diets in three different test-meals: without cephalic insulin release, meal size no longer seems to be modulated by oral cues.

Animals↗
PubMed2002

The comet assay with 8 mouse organs: results with 39 currently used food additives.

We determined the genotoxicity of 39 chemicals currently in use as food additives. They fell into six categories-dyes, color fixatives and preservatives, preservatives, antioxidants, fungicides, and sweeteners. We tested groups of four male ddY mice once orally with each additive at up to 0.5xLD(50) or the limit dose (2000mg/kg) and performed the comet assay on the glandular stomach, colon, liver, kidney, urinary bladder, lung, brain, and bone marrow 3 and 24h after treatment. Of all the additives, dyes were the most genotoxic. Amaranth, Allura Red, New Coccine, Tartrazine, Erythrosine, Phloxine, and Rose Bengal induced dose-related DNA damage in the glandular stomach, colon, and/or urinary bladder. All seven dyes induced DNA damage in the gastrointestinal organs at a low dose (10 or 100mg/kg). Among them, Amaranth, Allura Red, New Coccine, and Tartrazine induced DNA damage in the colon at close to the acceptable daily intakes (ADIs). Two antioxidants (butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT)), three fungicides (biphenyl, sodium o-phenylphenol, and thiabendazole), and four sweeteners (sodium cyclamate, saccharin, sodium saccharin, and sucralose) also induced DNA damage in gastrointestinal organs. Based on these results, we believe that more extensive assessment of food additives in current use is warranted.

Animals↗
PubMed2002

Aspartame optical biosensor with bienzyme-immobilized eggshell membrane and oxygen-sensitive optode membrane.

An aspartame optical biosensor has been fabricated by employing a bienzyme system composed of alpha-chymotrypsin and alcohol oxidase immobilized onto an eggshell membrane and an oxygen-sensitive optode membrane as the transducer. The detection schemes involve the enzymatic reactions of aspartame leading to the depletion of the oxygen level of the medium with a concomitant enhancement of the fluorescence intensity of the oxygen-sensitive membrane. The scanning electron and transmission electron micrographs show the microstructure of the eggshell membrane which is successfully immobilized with bienzyme. Using this novel immobilization technique, the aspartame biosensor shows extremely good stability with a shelf life of at least 8 months. The rate change of the fluorescence intensity in 4 min is found to be linearly related to the concentration of aspartame. The useful analytical working range of the biosensor is from 0.056 to 3.07 mM aspartame. The effects of temperature, pH, and ionic strength on the response of the aspartame biosensor are investigated in detail. Citric acid, cyclamic acid, D-fructose, D-galactose, D-glucose, hydrogen peroxide, DL-malic acid, L-phenylalanine, saccharin, sodium benzoate, and sucrose show no interferences but ethanol interferes strongly. The aspartame biosensor has been applied to determine aspartame contents in some commercial products.

Animals↗
PubMed2002

Synthesis and X-ray crystal structure determination of the first Copper(II) complexes of tetraazamacrocycle-glyoxal condensates.

Novel Cu(II) complexes CuLCl(2) (L = 1-4) have been synthesized containing the metal bound to a well-known type of tetracyclic bisaminal formed from the condensation of glyoxal and tetraazamacrocycles (1 = cyclam-glyoxal condensate, 2 = [13]aneN4-glyoxal condensate, 3 = cyclen-glyoxal condensate, 4 = isocyclam-glyoxal condensate). The four-coordinate complexes were characterized by X-ray crystallography, electronic spectroscopy, solid-state magnetic moments, and electron spin resonance spectroscopy. The tetracyclic bisaminals, although having four potential donor atoms, are bound in a cis-bidentate fashion to Cu(II) with two additional cis-chloride donors. The ligands take up folded conformations, and with the exception of ligand 4, only nonadjacent nitrogen atoms coordinate. As expected, ligand 2 in Cu(2)Cl(2) has a folded structure similar to those of the previously characterized 1 and 3. The conformation of 4 in the complex Cu(4)Cl(2) differs from 1-3 in that three nitrogens direct their lone pairs to one side of the folded tetracycle, with adjacent nitrogen atoms coordinated to Cu(II). This difference is probably caused by the presence of the more flexible seven-membered ring rather than the five- to six-membered rings in 1-3. Air oxidation of Cu(I) in the presence of 1 or 3 results in bis(mu-hydroxo) dimers as characterized by X-ray crystal structures, suggesting dioxygen binding, followed by O-O bond splitting to give the Cu(2)O(2) diamond core.

Journal Article↗
PubMed2002

Water soluble molecular switches of fluorescence based on the Ni(III)/Ni(II) redox change.

The water soluble Ni(II) complexes of the cyclam derivatives with 1,3-benzodioxole and 1,2,3-trimethoxybenzene display the fluorescent emission typical of the covalently linked fluorophores, which results from a charge transfer excited state. On oxidation to Ni(III), the fluorescence is completely quenched due to the occurrence of an electron transfer (eT) process from the excited fluorogenic fragment Fl to the oxidized metal. Thus, fluorescence can be switched off/on at will, for several cycles, by consecutively oxidizing and reducing the metal center, in controlled potential electrolysis experiments both in acetonitrile and in aqueous 0.1 M HClO4. Occurrence of an eT process from Fl to Ni(III) ultimately depends upon the easy oxidation of Fl to Fl+, whereas failure of the occurrence of an eT process from Ni(II) to Fl has to be ascribed to the particular resistance of Fl fragments to the reduction.

Journal Article↗
PubMed2003

Structural properties of cyclopentanone-bridged bis-macrocyclic ligand dicopper(II) complexes in the solid and in solution: a successful test of the MM-EPR method.

The copper(II)-assisted condensation of 2,3,2-tet (3,7-diazanonane-1,9-diamine) with formaldehyde and cyclopentanone yields the mono- and bis-macrocyclic Mannich condensation products L(1) and L(2), as well as the Schiff-base product L(3), all with cyclam-type tetraaza macrocycles, coordinated to copper(II). The combination of molecular mechanics and EPR spectroscopy (MM-EPR) reveals that all three isomers of [Cu(2)(L(2))(OH(2))(n)](2+) (n = 0-4), with the expected trans-III (R,R,S,S) configuration of the 14-membered tetraaza macrocycles, are of similar stability, and that the isomer whose structure is solved by X-ray crystallography has a different structure in solution.

Journal Article↗
PubMed2004

NMR spectroscopic and X-ray crystallographic study of methylcobalt(III) compounds with saturated amine ligands.

The (13)C chemical shifts of methylcobalt(III) compounds with saturated amine ligands in cis positions to the methyl group and a monodentate ligand, L = CN(-), NH(3), NO(2)(-), N(3)(-), H(2)O, or OH(-), in the trans position are reported. The amine ligands used, 1,2-ethanediamine (en), 1,3-propanediamine (tn), N,N'-bis(2-aminoethyl)-1,3-propanediamine (2,3,2-tet), N,N'-bis(3-aminopropyl)-1,2-ethanediamine (3,2,3-tet), and 1,4,8,11-tetraazacyclotetradecane (cyclam), all exert an apparent cis influence on the (13)C resonance signal of the coordinated methyl group. In the trans-[Co(en)(2)(CH(3))(L)](n+) series the (15)N resonance frequency of the coordinated en has also been measured. The influence of L on the en (15)N chemical shifts is reverse the influence on the methyl (13)C chemical shifts except in the case of L = NO(2)(-), which affects a further deshielding of the amine nitrogen nucleus. The methyl (1)J(CH) coupling constants in the trans-[Co(en)(2)(CH(3))(L)](n+) series range from 128.09 Hz (L = CN(-)) to 134.11 Hz (L = H(2)O). The crystal structures of trans-[Co(en)(2)(CH(3))(ClZnCl(3))], trans-[Co(3,2,3-tet)(CH(3))(N(3))]ClO(4), trans,trans-[(CH(3))(en)(2)Co(CN)Co(en)(2)(CH(3))](PF(6))(3)(CH(3)CN), and cis-[Co(en)(2)(CH(3))(NH(3))]ZnCl(4) were determined from low-temperature X-ray diffraction data.

Journal Article↗
PubMed2003

1H NMR studies of ligand and H/D exchange reactions of cis- and trans-([14]aneN4)(H2O)RhH2+ in aqueous solutions.

Substitution and exchange reactions of cis- and trans-L(1)(H(2)O)RhH(2+) (L(1) = 1,4,8,11-tetraazacyclotetradecane = [14]aneN(4)) were studied in aqueous solutions by UV-vis and (1)H NMR spectroscopies. At pH 1 and 25 degrees C, the substitution of SCN(-) for the coordinated molecule of water is rapid and thermodynamically favorable. Spectrophotometric determinations yielded the equilibrium constants K = 1.49 x 10(3) M(-1) (cis) and 1.44 x 10(3) (trans). (1)H NMR studies in D(2)O revealed a rapid dynamic process, interpreted as the exchange between coordinated water and X(-) (X = Cl, Br, or I). On the other hand, no line broadening was observed for the strongly bound ligands CN(-) and SCN(-). The complex trans-L(1)(D(2)O)RhH(2+) undergoes a base-catalyzed H/D exchange of the hydride in D(2)O with a rate constant of (1.45 +/- 0.02) x 10(3) M(-1) s(-1). The exchange in the cis isomer is very slow under similar conditions. The complex cis-[L(1)ClRhH](ClO(4)) crystallizes in the centrosymmetric Ponemacr; space group, unit cell dimensions a = 8.9805(11) A, b = 9.1598(11) A, c = 10.4081(13) A, alpha = 81.091(2) degrees, beta = 81.978(2) degrees, gamma = 88.850(2) degrees. The rhodium atom resides in a slightly distorted octahedral environment consisting of the four N atoms of the cyclam, a stereochemically active hydrogen, and a chlorine atom.

Journal Article↗