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PubMed1982

Stannous ion quantitation in 99mTc-radiopharmaceutical kits.

A simple and inexpensive method for the estimation of stannous ion, Sn (II), in radiopharmaceutical kits is described. The method used is a potentiometric titration of Sn (II) in 1 N HCI medium, using potassium iodate as the oxidizing agent in an atmosphere of nitrogen. The apparatus includes pH meter, a platinum electrode, and a simple titration cell. Several commonly used radiopharmaceutical kits were analyzed for their Sn (II) content using this method. These studies indicate that the procedure can be used, as a routine quantitative test for the Sn (II) content of various 99mTc-labeled radiopharmaceuticals.

Hydrogen-Ion Concentration↗
PubMed1991

Labelling of regenerating retinal pigment epithelium by colloidal iron oxide and ferritin conjugated to wheat germ agglutinin.

In order to determine if there are biochemical changes in plasma-membrane oligosaccharides of regenerating retinal pigment epithelium, the binding of colloidal iron oxide at low pH and ferritin-conjugated wheat germ agglutinin--probes of sialic acid and N-acetylglucosamine on the cell surface--was examined electron-microscopically. An animal model of retinal pigment epithelium regeneration--rabbits with sodium iodate induced retinopathy--was used. In this model, large expanses of regenerating pigment epithelium are present for comparison with zones of spared pigment epithelium in the same animals. In thin sections examined by transmission electron microscopy, ferritin-conjugated wheat germ agglutinin appeared to bind more intensely to the exposed plasma membrane of regenerating retinal pigment epithelium than to spared pigment epithelium, or that of normal rabbits. Morphometry verified this. Colloidal iron oxide intensely labelled the plasma membranes of regenerating, spared, and normal pigment epithelium, and was visibly reduced after exposure of tissue to neuraminidase. The observations indicate that the plasma membrane of regenerating retinal pigment epithelium bears sialic acid and N-acetylglucosamine residues as in normal retinal pigment epithelium. However, the amount of plasma membrane bearing exposed N-acetylglucosamine increases during regeneration.

Animals↗
PubMed2003

Analysis of iodine species in aqueous solutions.

Iodine is a biologically important trace element. Its behaviour in the environment and in human metabolism is determined by the type of iodine species which takes part in chemical reactions. Knowledge of their concentrations is necessary to understand and describe the iodine reaction paths. A separation procedure is proposed for quick determination of common forms of iodine-iodide, iodate ions, molecular iodine and organoiodine (in the form of CH(3)I). The procedure consists of sequential sorption by passing the sample solution first through a solid-phase extraction cartridge to separate I(2) and CH(3)I from IO(3)(-) and I(-) then through an anion-exchange resin in a cartridge to retain the latter two species. Each loaded cartridge is eluted to separate the sorbed pair of species. Concentration determination of the resulting four solutions can be performed by standard methods, e.g. by spectrophotometry, tracer counting or with ion-selective electrodes.

Journal Article↗
PubMed2004

Synthesis, characterization, and analytical application of zirconium(IV) selenoiodate, a new cation exchanger.

Zirconium(IV) selenoiodates have been synthesized under a variety of conditions. The most chemically and thermally stable sample is prepared by adding a mixture of aqueous solutions of 0.1 mol L(-1) potassium iodate and 0.1 mol L(-1) sodium selenite to aqueous solution of 0.1 mol L(-1) zirconium(IV) oxychloride. Its ion-exchange capacity for K+ and Pb2+ was found to be 3.20 and 2.35 meq g(-1) dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger at different temperatures has also been studied. The analytical importance of the material has been established by quantitative separation of Pb2+ from other metal ions.

Journal Article↗
PubMed2001

Modification of the electroosmotic flow and separation selectivity of anions in electrochromatography with pseudo-stationary phases of C14-alkyldimethylammoniopropane sulfonate zwitterionic surfactants by addition of salts to the background electrolyte.

The effects of salts (NaCl, NaClO4, MgCl2, CeCl3) added to background electrolyte (BGE) solutions (10 mmol L(-1) sodium phosphate, pH 7.2) on electroosmotic flow (EOF) and the separation selectivity of anions (chloride, bromide, iodide, nitrite, nitrate, chlorate, thiocyanate, iodate, chromate, and molybdate ion) by capillary electrochromatography using the zwitterionic surfactant 3-(N,N-dimethylmyristylammonio)propane sulfonate (C14N3S) as a pseudo-stationary phase were investigated. There are two mechanisms affecting the separations: 1. the cations and anions of the added salts interact with the zwitterionic surfactant to varying degrees, thus changing the overall retention of the analytes; and 2. they change the EOF and the resulting apparent mobilities. It was shown that a BGE containing perchlorate and a low concentration of zwitterionic surfactant (2 mmol L(-1)) gave a stable and reproducible EOF and the concentration of perchlorate could be used to manipulate the separation selectivity for polarizable anions, such as iodide and thiocyanate. These effects are discussed in terms of measured association constants describing the interaction of anions and cations with the zwitterion.

Anions↗
PubMed1998

Spiral CT angiography and surgical correlations in the evaluation of intracranial aneurysms.

We investigated the accuracy of spiral computed tomography angiography (CTA) in the detection and study of intracranial aneurysms by comparing CTA with selective angiograms and surgical findings. Twenty-six patients (9 men and 17 women; mean age 53.1 +/- 1.8 years) with suspected intracranial aneurysms were submitted to CTA (1- to 2-mm slices, pitch 1:1, 24 s, RI = 1) after a conventional CT examination showing subarachnoid hemorrhage (SAH) in 19 cases and during neuroradiological investigations performed for other reasons in 7 cases. One hundred twenty to 150 ml iodate contrast agent (0.3-0.4 gI/ml) were injected intravenously at 5 ml/s rate and with 12- to 25-s delay calculated with a preliminary test bolus. Three-dimensional shaded surface display (3D SSD) and maximum intensity projection (MIP) reconstructions were obtained from axial images. Then, within 48 h, all patients were submitted to digital subtraction angiography (DSA), with separate assessment of CTA and DSA findings. Twenty-two aneurysms shown by CTA were confirmed at DSA and surgery (true positives), whereas the vascular lesion was not confirmed at DSA in 2 cases (false positives). The presence of intracranial aneurysms was excluded at both CTA and subsequent DSA in 7 cases (true negatives) and there were no false negatives; sensitivity was 100 %, specificity 77.8 %, and diagnostic accuracy 93.5 %. Computed tomography angiography aneurysm location was confirmed at surgery in all cases, with very high accuracy in assessing the presence of an aneurysm neck (100 %). Computed tomography angiography accurately depicted the aneurysm shape in 20 of 22 cases, but failed to depict its multilobed nature in 2 cases. The mean aneurysm diameter calculated at CTA was 0.99 +/- 0.12 cm vs 1.09 +/- 0.11 cm at surgery (p < 0.01). The present results suggest that the high sensitivity of CTA, if confirmed by further studies, might help in avoiding having to resort to arteriography after negative CTA in SAH patients.

Adult↗
PubMed2006

Gastrointestinal stromal tumour: spiral computed tomography features and pathologic correlation.

PURPOSE: Our purpose was to define the diagnostic accuracy of helical computed tomography (CT) in the identification, characterisation and evaluation of extension of gastrointestinal stromal tumours (GIST) through correlation with some pathological findings. MATERIALS AND METHODS: Between August 2000 and September 2004, we conducted a retrospective study of the abdominal CT of 15 patients with histological diagnosis of GIST - that is, the immunopositivity for c-kit (CD117) - on a surgical specimen of the primary disease. We used a helical CT single-slice (Toshiba, Asteion; rotation time 0.75 s) in ten cases and helical CT multislice (Toshiba, Aquilion; 4 slices/rotation; rotation time 0.5 s) in five cases. In all cases, we used an organ-iodate nonionic contrast agent intravenously at a concentration of 350-400 mgI/ml. All cases studied the entire abdomen. Site, morphology and tumour size (smaller than 5 cm, 5-10 cm and larger than 10 cm) were considered parameters for tumour identification. Size, partial or total extraluminal tumour growth, homogeneous or inhomogeneous lesion enhancement and the eventual presence of calcifications were assumed to be criteria for characterisation of a GIST. Hepatic, peritoneal and/or lymph node metastases were considered parameters of intermediate or high malignancy. We correlated the results with some pathological features derived from the analysis of surgical tissue: site, morphology and tumour size, tissue components and risk of malignancy of GIST (on the basis of the 2002 Fletcher classification). RESULTS: We demonstrated one substantial concordance between radiological and pathological valuation of site, morphology, tumour size and absence of intralesional calcifications of GIST. Nine of ten GIST smaller than 5 cm, the two 5-10 cm and the three larger than 10 cm presented extraluminal growth. Enhancement was inhomogeneous in five of ten lesions smaller than 5 cm and in all cases larger than 5 cm. At pathological analysis, in all cases of inhomogeneous enhancement, solid, hemorrhagic, necrotic and cystic areas were found. Of seven tumours of intermediate malignancy, six were smaller than 5 cm and only one larger than 10 cm; the two 5-10 cm were of high malignancy and all tumours superior of 10 cm were at intermediate or high malignancy. Of the two cases with metastases, one was of intermediate and one of high malignancy. In the other cases of intermediate or high malignancy, metastases were absent. CONCLUSIONS: The immunopositivity for c-kit is requisite for definitive diagnosis of GIST, but imaging, and particularly helical CT, has a primary role. In this study, CT is was reliable for tumour identification. All tumours larger than 5 cm presented extraluminal growth, inhomogeneous enhancement, absence of calcifications and lymph node metastases. Furthermore, the tumour larger than 5 cm showed extraluminal growth and inhomogeneous enhancement. Tumour size established with CT was not sufficient to determine the degree of malignancy. Metastases at the time of diagnosis were indicative of intermediate or high malignancy, but the absence of metastases did not allow classification of GIST in the group of low and very low risk of malignancy.

Adult↗
PubMed1992

Blockade of sodium channels by Bistramide A in voltage-clamped frog skeletal muscle fibres.

The effect of Bistramide A, a toxin isolated from Bistratum lissoclinum Sluiter (Urochordata), on the peak sodium current (INa) of frog skeletal muscle fibres was studied with the double sucrose gap voltage clamp technique. External or internal application of Bistramide A inhibited INa without alteration of the kinetic parameters of the current nor of the apparent reversal potential for Na. The steady-state activation curve of INa was unchanged while the steady-state inactivation curve of INa was shifted towards more negative membrane potentials. Dose-response curves indicated an apparent dissociation constant for Bistramide A of 3.3 microM and a Hill coefficient of 1.2 which suggested a one to one relation between the toxin and Na channel. The inhibition of INa occurred at rest, and was more important at more positive holding potentials. Bistramide A exhibited only a weak frequency-dependent effect. The toxin did not interact with the use-dependent effect of lidocaine. It mainly blocked Na channels at more depolarized holding potentials. The toxin blocked Na channels when it was internally applyed and when the inactivation gating system has been previously destroyed by internal diffusion of iodate. The data suggest that Bistramide A inhibited the Na channel both at rest and in the inactivated state and occupied a site which was not located on the inactivation gate.

Acetamides↗
PubMed1984

Oxidation of thymidylate synthase by inorganic compounds.

Thymidylate synthase from methotrexate-resistant Lactobacillus casei was rapidly and completely inactivated by low concentrations of permanganate, periodate, or potassium triiodide at 0 degree C. The enzyme was not inactivated to any appreciable extent by iodate, iodide, ferricyanate, iodosobenzoate, or hydrogen peroxide. The inactivation by permanganate was retarded by the substrate 2'-deoxyuridylate and, to a lesser extent, by phosphate. Titration of enzyme activity with permanganate showed that two moles of permanganate were required to completely inactivate one mole of thymidylate synthase.

Indicators and Reagents↗
PubMed1980

Effect of iodide on estrogen-induced uterine peroxidase.

Iodide administered in the drinking water for 5-7 days increased the activity of estradiol-induced uterine peroxidase in the immature rat. This effect was specific for iodide and could not be mimickead by chloride, bromide, thiocyanate, perchlorate or iodate. Sodium iodide also increased peroxidase activity in the parotid gland but had no effect on glucose-6-phosphate dehydrogenase in the uterus, thyroid or parotid even though estradiol produced a 2-fold increase in the activity of this enzyme in the uterus. 125I was taken up more readily by the uterus than by muscle but this process was not influenced by prior treatment of the animals with estrogen. The in vitro effect of sulfhydryl reagents on uterine peroxidase was also investigated and proposals made for possible mechanisms of action of iodide on this enzyme in the intact animal.

Animals↗
PubMed1984

Amino conjugates of a phosphatidylglycerol oxidation product: novel adjuncts for liposome preparation.

Amino groups in amino acids, proteins and possibly glycoproteins could be conjugated to a product of per-Iodate oxidation of phosphatidyglycerol. The reaction yields an unstable Schiff's base, which could be converted to a more stable phosphatidylethanol derivative of the respective amino acid or protein, by a reducing agent such as sodium borohydride. Such derivatives may be a useful alternative to stearylamine in the preparation of cationic liposomes intended for use in enzyme replacement and drug therapy. They may be useful in preparing liposomes with stable glycoprotein and protein moieties sticking outwards on the surface of the vesicle; an important development in the effort to achieve selective homing or targetting of liposomally entrapped therapeutic agent to specific tissues.

Amines↗
PubMed2005

Carbonic anhydrase inhibitors. Inhibition of isozymes I, II, IV, V, and IX with anions isosteric and isoelectronic with sulfate, nitrate, and carbonate.

The inhibition of five human carbonic anhydrase (hCA, EC 4.2.1.1) isozymes; the cytosolic hCA I and II, the membrane-bound hCA IV, the mitochondrial hCA V, and the tumor-associated, transmembrane hCA IX, with anions isosteric and isoelectronic with sulfate, nitrate, and carbonate; such as chlorate, perchlorate, bromate, iodate, periodate, silicate, bismuthate, vanadate, molybdate, and wolframate is reported. Apparently, the geometry of the inhibitor (tetrahedral or trigonal) does not influence its binding to the Zn(II) ion of the enzyme active site, but the nature of the central element is the most important factor influencing potency. Isozymes hCA I and II are best inhibited by chlorate, perchlorate, and silicate, together with the anions structurally related to sulfate, sulfamate, and sulfamidate, but sulfate itself is a weak inhibitor (inhibition constant of 74 mM against hCA I and 183 mM against hCA II). Molybdate is a very weak hCA I inhibitor (K(I) of 914 mM) but it interacts with hCA II (K(I) of 27.5mM). Isozyme IV is well inhibited by sulfate (K(I) of 9 mM), sulfamate, and sulfamidate (in the low micromolar range), but not by perchlorate (K(I) of 767 mM). The mitochondrial isozyme V has the lowest affinity for sulfate (K(I) of 680 mM) and carbonate (K(I) of 95 mM) among all the investigated isozymes, suggesting on one hand its possible participation in metabolon(s) with sulfate anion exchanger(s), and on the other hand an evolutionary adaptation to working at higher pH values (around 8.5 in mitochondria) where rather high amounts of carbonate in equilibrium with bicarbonate may be present. Metasilicate, isosteric to carbonate, is also about a 10 times weaker inhibitor of this isozyme as compared to other CAs investigated here (K(I) of 28.2 mM). Surprisingly, the tumor-associated isozyme IX is resistant to sulfate inhibition (K(I) of 154 mM) but has affinity in the low micromolar range for carbonate, sulfamate, and sulfamidate (K(I) in the range of 8.6-9.6 microM). This constitutes another proof that this isozyme best works at acidic pH values present in tumors, being inhibited substantially at higher pH values when more carbonate may be present. Bromate and chlorate are quite weak CA IX inhibitors (K(I) s of 147-274 mM).

Anions↗
PubMed2004

Capillary electrophoresis as a useful tool for the analysis of chemical tracers applied to hydrological systems.

A capillary electrophoretic method was optimised for the separation and determination of iodide used as artificial tracer in hydrology. The influence of the buffer concentration and pH, electroosmotic flow modifier concentration (cetyltrimethylammonium bromide (CTAB)), the injection time and voltage applied, on the electrophoretic separation was studied. A running buffer of 20 mM phosphate (pH 8) containing 1 mM CTAB was found to provide the optimum separation of iodide with respect to resolution, migration time and selectivity. The water samples were injected hydrostatically at 10 cm for 110 s, the voltage applied was -20 kV and a detection wavelength of 214 nm. The influence of the sulphite added to water samples in order to prevent the oxidation of iodide to iodate was also studied. This method can be applied to the determination of iodide free of sulphite interference up to at least a ratio of 1:1000 (I(-):SO3(2-)). The other inorganic anions, which are present in the water samples (mainly chloride, sulphate, nitrate, carbonate), do not interfere with the determination of iodide. This method allows the simultaneous determination of bromide, nitrite, and nitrate together with iodide. The electrophoretic method showed to be linear from 0.5 to 5 mg l(-1) of iodide (the migration time was 2.6 min) with a quantitation limit of 0.45 mg l(-1) and a intraday repeatability lower than 4% of R.S.D. at different concentration levels.

Electrophoresis, Capillary↗
PubMed2005

Preparation and testing of stationary phases and modified capillaries for affinity chromatography and affinity capillary electrophoresis of pepsin.

Three stationary phases have been prepared for affinity liquid chromatography isolation and separation of porcine and human pepsin. The phases contain 3,5-diiodo-L-tyrosine (DIT) bound to the supports HEMA BIO VS, HEMA BIO E and EPOXY TOYOPEARL. These phases have been tested on a model sample of porcine pepsin A and applied to human pepsin. Fractions have been collected and the chymase activity determined in selected analyses. For affinity CE, capillaries have been prepared by modifying the wall with 3-aminopropyltriethoxysilane, followed either by direct binding of DIT, or by binding L-tyrosine that was subsequently iodated. The dissociation constant K(d) has been determined for the pepsin-DIT complex from the changes in the electrophoretic mobilities.

Animals↗
PubMed2005

Analysis of iodinated X-ray contrast agents in water samples by ion chromatography and inductively-coupled plasma mass spectrometry.

In this paper, an analytical method for the determination of six iodinated X-ray contrast agents (amidotrizoic acid, iohexol, iomeprol, iopamidol, iopromide, and ioxitalamic acid), iodide, and iodate in water samples is presented. The method is based on a separation of the analytes by ion chromatography (IC) and a subsequent detection by inductively-coupled plasma mass spectrometry (ICP-MS). The method was optimised with respect to separation conditions (column type and eluent composition) and extensively validated. Without pre-concentration of the samples, limits of detection below 0.2 microg/l could be achieved whereby reproducibility was below 6% for all compounds under investigation.

Chromatography, Ion Exchange↗
PubMed2005

Use of temperature programming to improve resolution of inorganic anions, haloacetic acids and oxyhalides in drinking water by suppressed ion chromatography.

Temperature programming was used to improve selectivity in the suppressed ion chromatographic (IC) separation of inorganic anions, haloacetic acids and oxyhalides in drinking water samples when using NaOH gradient elution. The programme exploited varying responses of these anions to changes in temperature. Heats of adsorption (deltaH, kJ/mol) for 17 anionic species were calculated from van't Hoff plots. For haloacetic acids, both the degree of substitution and log P (log of n-octanol-waterpartition coefficient) values correlated well with the magnitude of the temperature effect, with monochloro- and monobromoacetic acids showing the largest effect (deltaH= -10.4 to -10.7 kJ/mol), dichloro- and dibromoacetic acids showing a reduced effect (deltaH= -6.8 to -8.4 kJ/mol) and trichloro-, bromodichloro- and chlorodibromoacetic acids showing the least effect (deltaH= -4.7 to -2.4 kJ/mol). The effect of temperature on oxyhalides ranged from deltaH= 8.4 kJ/mol for perchlorate to deltaH= -9.1 kJ/mol for iodate. The effectiveness of two commercial column ovens was investigated for the application of temperature gradients during chromatographic runs, with the best system applied to improve the resolution of closely retained species at the start, middle and end of the separation obtained using a previously optimised hydroxide gradient, in a real drinking water sample matrix. Retention time reproducibility of the final method ranged from 0.62 to 3.18% RSD (n = 30) showing temperature programming is indeed a practically important parameter to manipulate resolution.

Acetates↗
PubMed2005

N-Methylimidazolium anion-exchange stationary phase for high-performance liquid chromatography.

In this paper, the preparation of a new anion-exchange phase based on N-methylimidazolium immobilized on silica is described. HPLC separations of common inorganic anions, including an iodate, chloride, bromide, nitrate, iodide, and thiocyanate, were performed using a HPLC column (200 x 4.6mm I.D.) packed with the said phase, and phosphate buffer solution and acetate buffer solution as the mobile phases respectively, with UV detection at 200 nm. The effects of pH and the concentration of the eluent on the separation of anions were studied. With the efficiency and resolution of the column calculated, the results showed that this new phase can be used in the analysis of these in organic anions with great prospects. At the same time, successful separations of some organic anions, amines and nucleotides have also been obtained respectively using this new phase. The phase displayed a main strong anion-exchange mechanism and a coexistent reverse-phase interaction, etc.

Anions↗