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At least 487 records · Page 27Linked to original sources
PubMed2000

An alternative approach to the preparation of (188)Re radiopharmaceuticals from generator-produced [(188)ReO(4)](-): efficient synthesis of (188)Re(V)-meso-2,3-dimercaptosuccinic acid.

A new efficient approach for the preparation of (188)Re radiopharmaceuticals starting from [(188)ReO(4)](-), produced at a carrier-free level through the (188)W/(188)Re generator system, is described. The reaction procedure was based on the combined action of different reagents and has been applied in detail to the preparation of the therapeutic agent (188)Re(V)-DMSA (H(2)DMSA [meso-2,3-dimercaptosuccinic acid]). The most efficient combination required the use of SnCl(2), oxalate ions, and gamma-cyclodextrin. These were reacted with [(188)ReO(4)](-) and H(2)DMSA to afford the final radiopharmaceutical in high radiochemical purity, at room temperature, and in weakly acidic solution. The role played by the various reagents in the reaction was investigated. It was found that SnCl(2) behaved as the actual reducing agent, whereas oxalate and gamma-cyclodextrin greatly enhanced the ease of reduction of [(188)ReO(4)](-) through the action of two hypothetical mechanisms. In the first step of the reaction, oxalate ions gave rise to the formation of Re(VII) complexes with the concomitant expansion of the coordination sphere of the metal. This process strongly favored the electron transfer between Sn(2+) and Re(+7) centers, giving rise to intermediate reduced rhenium complexes. These species were further stabilized by the formation of transient host-guest aggregates with gamma-cyclodextrin and finally converted into (188)Re(V)-DMSA through simple replacement of the coordinated ligands by H(2)DMSA.

Cyclodextrins↗
PubMed1996

99mTc-2GAM: a tracer for renal imaging.

We propose a renal imaging agent, the 99mTc complex of the bidentate-N,S chelate N-(mercaptoacetyl)glycine (99mTc-2GAM), with the imaging characteristics of 99mTc-DMSA but a faster kidney uptake; chemical evidence supports the formulation of 99mTc-2GAM as [Tc(v)(O)(GAM)2]-. After biodistribution and toxicity studies in animals, 99mTc-2GAM was evaluated in five normal volunteers. 99mTc-2GAM is rapidly cleared from the blood (t1/2 = 9 min) and 50% of the ID is excreted in the urine in the first 2 h. Dynamic data show a rapid renal uptake that increases up to 1 h with no significant wash-out between 1 and 8 h. The uptake in each kidney ranges from 11.3% to 20.7% ID. Low, stable liver uptake is observed. No significant activity is detected in other organs. We showed no differences between 99mTc-2GAM and 99mTc-DMSA compared in three patients with unilateral kidney disease. We conclude that 99mTc-2GAM has good practical and dosimetric features for renal imaging.

Adult↗
PubMed1996

Preparation of radioactive lead complexes utilizing Chelex methodology.

The use of Chelex resin for the synthesis of radioactive lead complexes has been explored. The process involved immobilization of 203Pb on the resin and subsequent elution of complexed lead by chelating agents. 203Pb complexes derived from meso- and racemic dimercaptosuccinic acid (meso-DMSA, rac-DMSA) were prepared and assessed for stability in vitro.

Chelating Agents↗
PubMed1999

Carrier effect on radiolabeling the polynuclear pentavalent rhenium-186 complex of dimercaptosuccinic acid at alkaline pH: 186Re(V)-DMS.

Radiolabeling with rhenium (Re-186, Re-188), a tumor agent to resemble the pentavalent polynuclear technetium complex of dimercaptosuccinic acid (99mTc[V]-DMS) has been reported for radiotherapeutical use. Nevertheless, despite the periodic analogies between both radiometals, differences in the redox potential and the carrier concentration have made the radiolabeling of the rhenium counterpart difficult. In the present study, the effect of the carrier contained in the reactor-produced Re-186 was estimated as an important factor relevant to the Re-186 radiolabeling of DMS at an alkaline pH. Great effect of the carrier Re with an inverse correlation with the stannous ion was an interesting phenomenon relevant for an assumption on the Sn participation in the complex. Under strict control of various labeling parameters, the 186Re(V)-DMS was made available with high yield (93-97%) at an alkaline pH and at room temperature. The great effect of carrier offers support to the polymeric or polynuclear nature of the rhenium complex of DMS as depicted in the drug design basis of its parent Tc(V)-DMS. The biodistribution studies of Re(V)-DMS showed mimetic characteristics with its parent Tc(V)-DMS drug.

Animals↗
PubMed1998

Acute childhood pyelonephritis: predictive value of positive sonographic findings in regard to later parenchymal scarring.

RATIONALE AND OBJECTIVES: The authors evaluated the importance of positive sonographic findings in acute childhood pyelonephritis. MATERIALS AND METHODS: A total of 290 children (91 boys, 199 girls, aged 4 days to 15 years [median, 394 days]) with clinically suspected acute pyelonephritis underwent initial renal gray-scale ultrasound (US) and dimercaptosuccinate scintigraphic examination within 3 days of onset. A total of 173 patients underwent color or energy US examination. One hundred fifteen children with normal scintigraphic or pathologic findings (other than acute pyelonephritis) were excluded from further study; 170 patients with abnormal scintigraphic findings underwent follow-up scintigraphic scanning 60-90 days later. RESULTS: When pathologic structures other than acute pyelonephritis were not considered, the diagnostic value of gray-scale US was poor, with a sensitivity of 45.5%, a specificity of 86.6%, a positive predictive value of 88.8%, and a negative predictive value of only 40.6%. In regard to future renal scarring, gray-scale US had a positive predictive value of 67.7%, a negative predictive value of 40%, and a likelihood ratio of 1.16. Abnormal Doppler findings helped predict future scarring with a positive predictive value of 85.7%, a negative predictive value of 37.2%, a very low sensitivity of 26.9%, a high specificity of 90.6%, and a likelihood ratio of 2.87. CONCLUSION: Positive US Doppler findings in children with clinically suspected acute pyelonephritis indicate the need for immediate treatment. A positive initial gray-scale US examination does not predict future renal scarring, but a positive Doppler examination indicates a high probability of scarring. Negative gray-scale or Doppler US does not exclude a diagnosis of acute pyelonephritis and it cannot predict an absence of future scarring.

Acute Disease↗
PubMed1978

Studies with Brugia pahangi. 18. Anthelmintic effects of stibocaptate.

Stibocaptate (Asiban, Hoffman--La Roche) killed third stage larvae of Brugia pahangi in vitro at 50 p.p.m. but had no effect on microfilariae at 1 X 10(4) p.p.m No larvae developed in infected mosquitoes fed 1% stibocaptate in 10% sucrose. It was neither micro-nor macrofilaricidal in either jirds or cats but did affect embryogenesis.

Animals↗
PubMed1990

Schistosoma haematobium: the effect of Astiban on the cell composition and ultrastructure of the vitelline gland and the ultrastructure of the tegument and gastrodermis.

Treatment of Schistosoma haematobium (Nigerian strain) in hamsters with a single dose of 40 mg/kg of Astiban caused a reduction in the number of S1, S2, and S3 vitelline cells and an increase in S4 cells. Following seven daily doses of the drug, a marked reduction in S1 cells and a complete loss of S2 and S3 cells occurred such that 95% of the cells were S4 cells, all of which were structurally abnormal. Coagulation and disintegration of the protein granules of the vitelline droplets occurred with increase in lipid droplets, swelling of the nuclear membrane and an increase in cytosegresomes. Blebbing of the tegument in both sexes occurred following a single treatment and vacuolation of the basal infolds and alterations to the mitochondria also resulted, but severe erosion of the tegument was rare even following repeated drug treatment. Damage to the gastrodermis was severe with the development of autophagic vacuoles containing whorls of myelin and sequestered portions of damaged tissue. The degree of damage increased with the number of drug treatments.

Animals↗
PubMed1984

Schistosoma mansoni: an in vivo study of drug-induced autophagy in the gastrodermis.

The effects of Astiban, Lucanthone, Hycanthone and Niridazole on autophagic activities in the gastrodermis of Schistosoma mansoni were determined in vivo, using different dosage levels and dosage times. With Astiban, high levels of autophagy were observed in the gastrodermis 2 hours after an injection of the drug into the mouse, and this response had declined by 20 hours, marking a recovery by the parasite from the drug. Hycanthone and Lucanthone produced an autophagic response several days after the onset of treatment, and no recovery was observed in the morphology of the gastrodermis after the drug was discontinued. The effects of Niridazole on the gastrodermis were to produce the most dramatic ultrastructural changes after high doses and over several days of treatment. With all the drugs examined, gastrodermal autophagy was characterized by the formation of vacuoles containing cell components, lipid droplets and sometimes hydrolytic enzyme reaction product. The autophagic vacuoles appeared to be formed by the sequestration of cytoplasmic material by the basal membrane infoldings, and the transfer of enzymes into the vacuole from within the limiting membrane. The residues from intracellular digestion appeared to be emptied into the caecal lumen.

Animals↗
PubMed1990

Scintigraphic evaluation of glomus tumours.

The current investigations of choice for a suspected glomus tumour are either direct or indirect angiography to include digital subtraction followed by computerized tomography (CT) or magnetic resonance imaging (MRI) or, if available, CT and MRI with gadolinium alone. Although these modalities confirm the diagnosis and give anatomical information to facilitate accurate staging, they do not provide functional data. The use of radionuclide scintigraphy can add an extra physiological dimension to glomus tumour imaging. Iodine-131/123 metaiodobenzylguanidine (MIBG) is a tumour imaging agent which has been used to diagnose head and neck neuroendocrine tumours to include paragangliomata and medullary carcinoma of the thyroid (MCT). However, it is expensive and the new head and neck tumour imaging agent technetium-99 m (Tc99m) (v) dimercaptosuccinic acid (DMSA) has superceded it as the imaging agent of choice to evaluate MCT. We report a patient with a glomus jugulare tumour which was evaluated with I131/I123-MIBG and Tc99m (v) DMSA. The tumour was functional and is the first reported case exhibiting positive accumulation of both I131-MIBG and Tc99m (v) DMSA. The patient was subsequently treated with a therapeutic dose of I131-MIBG. The significance of these results is discussed.

3-Iodobenzylguanidine↗
PubMed1990

Technetium-99m(v) dimercaptosuccinic acid planar scintigraphy in head and neck cancer: clinical, scintigraphic and radiological study.

Technetium-99m (Tc99m)(v) Dimercaptosuccinic Acid (DMSA) is an imaging agent which has been proposed as a scintigraphic marker for head and neck squamous cell carcinoma. Fifty-four patients were studied of whom 51 had a head and neck tumour. All patients were examined and then imaged using Tc99m(v) DMSA scintigraphy and computerized tomography. Scintigraphy was less sensitive than clinical examination in the detection of patients with cancer, patients with primary tumours and patients with metastatic neck disease. CT was as sensitive and as accurate as clinical examination but more sensitive than Tc99m(v) DMSA in detecting patients with cancer and with primary tumours. CT was more sensitive and more accurate than both clinical examination and Tc99m(v) DMSA scintigraphy in predicting which patients had metastatic neck disease. Although Tc99m(v) DMSA is accumulated by squamous cell carcinoma, its inability to detect low volume disease and apparent low specificity means it has no role to play in the management of patients with head and neck squamous cell carcinoma.

Adult↗
PubMed1978

Accumulation and removal of Hg203 in different regions of the rat brain.

We have studied the brain regional distribution of methyl mercury following intravenous administration of CH3 203HgCl in rat. Early peak levels were obtained in cerebellum, medulla oblongata and midbrain. The efficacy of removal of 203Hg by different chelators is also region dependent. The most efficient chelator for brain mercury proved to be mesodimercaptosuccinic acid.

Animals↗
PubMedDate not supplied

Preparation and biological characterization of isomeric 188Re(V) oxocomplexes with tetradentate S4 ligands derived from meso-dimercaptosuccinic acid for labeling of biomolecules.

A new type of tetradentate S4 ligand has been synthesized by bridging two molecules of meso-2,3-dimercaptosuccinic acid for stable binding and easy conjugation of rhenium-188 to tumor targeting structures. The stereoisomeric tetrathiolato S4 ligands form very robust anionic five-coordinated oxorhenium(V) and oxotechnetium(V) complexes. Two routes for the preparation of the (188)Re(V) oxocomplexes with (iBu)2N(O)C-C(SH)C(SH)C(O)NH(CH2)3NH(CH2)3NHC(O)C(SH)C(SH)C(O)N(iBu)2 (ligand 1) and its hydrophilic crown ether derivative (ligand 2) were tested and optimized. Several isomers were separated by HPLC from the preparation solutions and characterized in vitro and in vivo. The identity of the species obtained was determined by comparison with the HPLC profiles of reference (185/187)Re analogues and (99/99m)Tc complexes which were characterized by ESI-MS. All of them were absolutely stable in rat and human plasma solutions. Challenge experiments with cysteine corroborated the high inertness of the isomers toward ligand exchange reactions. Various in vivo samples, taken off at different times from blood, intestine, and urine of rats, confirmed the high in vivo stability of the (188)Re-S4 complexes. Biodistribution studies using male Wistar rats were performed and exhibited a high uptake and fast clearance from the liver of the more lipophilic cis and trans isomers of complex I (log P(o/w) between 1.5 and 1.7), whereas the isomers of the hydrophilic complex II (log P(o/w) about -1.75) were rapidly excreted via the renal and the hepatobiliary pathway. The low level of activity in the stomach confirms good in vivo stability. Thus, these new (188)Re-S4 complexes fulfill the requirements for a stable and high specific activity labeling of biomolecules with rhenium-188.

Animals↗
PubMed2006

In vitro interactions between DMSA-coated maghemite nanoparticles and human fibroblasts: A physicochemical and cyto-genotoxical study.

Although the current production of oxide nanoparticles may be modest, the wide range of proposed applications and forecasted growth in production has raised questions about the potential impact of these nanoparticles on the environment and human health. Iron oxide nanoparticles have been proposed for an increasing number of biomedical applications although in vitro toxicity depending on the particles coating has been evidenced. The aim of this study was to examine the potential in vitro cyto- and genotoxicity on human dermal fibroblasts of DMSA-coated maghemite nanoparticles (NmDMSA) as a function of well-defined physicochemical states. Well-stabilized NmDMSA produced weak cytotoxic and no genotoxic effects. This is attributed in part to the DMSA coating, which serves as a barrier for a direct contact between nano-oxide and fibroblasts, inhibiting a potential toxic effect.

Fibroblasts↗
PubMed2005

Thermodynamics of the As(III)-thiol interaction: arsenite and monomethylarsenite complexes with glutathione, dihydrolipoic acid, and other thiol ligands.

Colorimetric (near-UV absorption spectroscopy) and calorimetric (isothermal titration calorimetry) methods have been used to quantify the equilibrium and thermodynamics of arsenite and monomethylarsenite (MMA) coordinating to glutathione (GSH) and the dithiols dimercaptosuccinic acid (DMSA), dihydrolipoic acid (DHLA), and dithiothreitol (DTT). We found that both arsenite and MMA form moderately stable complexes (beta = 10(6)-10(7)) with GSH; that arsenite forms a particularly stable 2:3 complex (beta approximately 10(18)) with the biological cofactor DHLA; that MMA has a somewhat higher affinity than arsenite for thiol ligands; and that entropic factors modulate the overall stability of As(III) complexes with thiols, which are favored by the exothermic formation of As(III)-thiolate bonds. The implications of these results for arsenic toxicity are discussed.

Arsenates↗
PubMed2005

Novel rhenium chelate system derived from dimercaptosuccinic acid for the selective labeling of biomolecules.

This work is part of an effort to develop chelating agents for stable binding and easy conjugation of Re-188 to biologically interesting structures. Starting from the well-known in vivo stability of [(188)ReO(DMSA)(2)](-), we want to exploit this coordination system for the design of (188)ReO(V) chelates, which are stable toward reoxidation to perrhenate and toward ligand exchange under all conditions of radiopharmaceutical development. Therefore, a new type of tetradentate ligand has been synthesized by bridging two molecules of N,N'-diisobutyl-2,3-dimercaptosuccinamide with N-(3-aminopropyl)propane-1,3-diamine. The resulting stereoisomeric tetrathiolato S(4) ligand of composition ((i)()Bu)(2)N(O)C-C(SH)-C(SH)-C(O)NH-(CH(2))(3)-NH-(CH(2))(3)-NHC(O)-C(SH)-C(SH)-C(O)N((i)Bu)(2) forms anionic five-coordinate oxorhenium(V) complexes by a ligand-exchange reaction of NBu(4)[ReOCl(4)] in methanol. In the absence of a base, the compounds were isolated as "betaine", [ReO(S(4))], with the protonated nitrogen of the bridge serving as an internal "counterion". Two representatives have been fully characterized in both the solid and solution states and found to adopt the expected square-pyramidal coordination geometry. The equatorial plane is formed by four thiolate sulfur atoms, whereas the oxygen occupies the apical position. The orientation of the metal oxo group is exo in relation to the carbamido groups in both isomers. Both complexes are stereoisomeric regarding the junction of the triamine chain.

Chelating Agents↗
PubMed2006

Biofunctional ZnO nanorod arrays grown on flexible substrates.

A square pattern of thioctic acid self-assembled ZnO nanorod arrays was grown on a large 4-in. thermoplastic polyurethane (TPU) flexible substrate via an in situ soluthermal process at low temperature (348 K). With the addition of dimercaptosuccinic acid (DMSA), the surface chemistry forms a disordered ZnO phase, and the morphology of the ZnO-DMSA nanorods changes with various DMSA addition times. As evidenced by the Zn2p3/2, C1s, O1s, S2p, and N-1s scans of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), DMSA and proteins were conjugated on the single crystalline ZnO nanorods. The photoluminescence (PL) spectra indicated that the optical properties of ZnO nanorod arrays were changed while the DMSA was inserted, and proteins were conjugated. Furthermore, a control test found that the ZnO nanorods show a significant improvement in sensitive characterization over the ZnO film. As another proteins (e.g., human serum albumin, HSA) were bound onto the ZnO-bovine serum albumin (BSA) nanorod arrays, an enhanced ultraviolet emission intensity was detected. On the basis of these results, one might be expected to conjugate specific biomolecules on the biofunctional ZnO nanorod arrays to detect the complementary biomolecules by PL detecting.

Animals↗
PubMed2006

Fluorescence-modified superparamagnetic nanoparticles: intracellular uptake and use in cellular imaging.

This report describes the preparation and characterization of new magnetic fluorescent nanoparticles and our success in using them to label living cells. The bifunctional nanoparticles possess a magnetic oxide core composed of a dimercaptosuccinic acid (DMSA) ligand at the surface and a covalently attached fluorescent dye. The nanoparticles exhibited a high affinity for cells, which was demonstrated by fluorescence microscopy and magnetophoresis. Fluorescence microscopy was used to monitor the localization patterns of magnetic nanoparticles associated with cells. We observed two types of magnetic labeling: adsorption of the nanoparticles on the cell membrane (membranous fluorescence) and internalization of the nanoparticles inside the cell (intracellular vesicular fluorescence). After internalization, nanoparticles were confined inside endosomes, which are submicrometric vesicles of the endocytotic pathway. We demonstrated that endosome movement could be piloted inside the cell by external magnetic fields such that small fluorescent chains of magnetic endosomes were formed in the cell cytoplasm in the direction of the applied magnetic field. Finally, by measuring the critical cellular magnetic load (quantitated by magnetophoresis), we have demonstrated the potential of this new magneto-fluorescent nanoagent for medical use.

Endosomes↗
PubMedDate not supplied

2,3-Dithioerythritol, a possible new arsenic antidote.

British antilewisite (2,3-dimercaptopropanol; BAL) has long been used as an arsenic antidote, but its therapeutic efficacy is limited by its inherent toxicity. We synthesized two less toxic derivatives of BAL and investigated their potential as antidotes to organic arsenic. The new compounds, 2,3-dithioerythritol (DTE) and 2,2-dimethyl-4-(hydroxymethyl)-1,3-dithiolane (isopropylidene derivative of BAL), react readily with phenyldichloroarsine (PDA) to yield the expected corresponding cyclic 1,3-dithioarsolanes. The BAL derivatives were compared to BAL in terms of their cytotoxicity and their ability to rescue PDA-poisoned mouse lymphoma cells in culture. The dithiolane was not a good antidote in the cultured cell system. In contrast, DTE was less toxic than BAL or DMSA and was superior at improving cell survival in PDA-exposed cells.

Animals↗