Radiolabeling of anti-carcinoembryonic antigen (CEA) monoclonal antibody (MAb BW 431/26) for clinical applications

A method for labeling of anti-carcinoembryonic antigen (CEA) monoclonal antibody (MAb) BW 431/26 is described. For preparations of^99mTc-anti-CEA complex, a solution (1 ml) of tetrasodium-1,1,3,3-propanetetetraphosphate dihydrate (2.7 mg), stannous chloride dihydrate (0.12 mg) and sodium chloride (0.2 mg) in 5 ml of 0.9% saline was added to a vial containing monoclonal antibody (2 mg) from mouse (MAb BW 431/26), D-glucitol (2 mg) and sodium sulfate (2 mg) to obtain a clear solution. A quantitative labeling yield of the MAb BW 431/26 was achieved by addition of 5 ml (40.5 mCi, 1.5 Gbq) technetium-99m-pertechnetate (^99mTcO₄) generator eluate at room temperature within 10 minutes. The radiochemical purity determined by ITLC (Gelman, SG) plates was >95%.     

99mTc-Exorphin-glucuronide in tumor diagnosis: Preparation and biodistribution studies in rats

Summary  Elérh     

Photochemistry and phototoxicity studies of flutamide, a phototoxic anti-cancer drug

The phototoxic anti-cancer drug flutamide is photolabile under UV-B light in either aerobic or anaerobic conditions. Irradiation of a methanol solution of this drug produces several photoproducts, one by photoreduction of the nitro group, one by rupture of the aromatic-NO2 bond of the parent compound, two as a result of the rupture of the CO-NH bond and one derived from the photoreduction product by scission of the aromatic-NH2 bond. Flutamide shows a photohemolytic effect on human erythrocytes and photoinduces lipid peroxidation. Studies on peripheral blood polymorphonuclear cells (neutrophils) demonstrated the phototoxicity of flutamide as well as inhibition of the cytotoxicity respiratory burst by the photoproduct derived from its photoreduction. The results suggest that the inhibition of the respiratory burst observed in phorbol myristate acetate (PMA)-activated cells is mediated by photosensitization and concomitant singlet oxygen production and/or formation of toxic photoproducts.     

117mSn-TTHMP的制备及生物性质研究

合成了具有亲骨性的氨基膦酸配体-TTHMP(三乙基四胺六甲撑膦酸),制备了117mSn(Ⅳ)-TTHMP,对配合物的稳定性、亲脂性作了研究,考察了它在大白兔体内显像及小鼠体内的分布。将其生物性质与已有文献报道的117mSn(Ⅳ)-HEDTMP作了比较。结果表明117mSn(Ⅳ)-TTHMP的制备简单,稳定性好,亲水,117mSn(Ⅳ)-TTHMP的靶向摄取率高于前两者,是一种极具潜力的新型放射性药物。     

Preparation,molecular modeling and biodistribution of 99mTc-phytochlorin complex

Phytochlorin [21H, 23H-Porphine-7-propanoicacid, 3-carboxy-5-(carboxymethyl)13-ethenyl-18-ethyl-7,8-dihydro-2,8,12,17-tetramethyl-,(7S,8S)] was labeled with ^99mTc and the factors affecting the labeling yield of ^99mTc-phytochlorin complex were studied in details. At pH 10, ^99mTc-phytochlorin complex was obtained with a high radiochemical yield of 98.4 ± 0.6 % by adding ^99mTc to 100 mg phytochlorin in the presence of 75 μg SnCl₂·2H₂O after 30 min reaction time. The molecular modeling study showed that the structure of ^99mTc-phytochlorin complex presents nearly linear HO–Tc–OH unit with an angle of 179.27° and a coplanar Tc(N1N2N3N4) unit. Biodistribution of ^99mTc-phytochlorin complex in tumor bearing mice showed high T/NT ratio (T/NT = 3.65 at 90 min post injection). This preclinical study showed that ^99mTc-phytochlorin complex is a potential selective radiotracer for solid tumor imaging and afford it as a new radiopharmaceutical suitable to proceed through the clinical trials for tumor imaging.     

Preparation and quality control and biodistribution studies of [90Y]-DOTA-cetuximab for radioimmunotherapy

Yttrium-90 is a useful radionuclide for radioimmunotherapy (RIT) and the anti-epidermal growth factor receptor (anti-EGFR) antibody cetuximab is clinicsally approved for the treatment of EGFR-expressing metastatic colorectal cancer and advanced head and neck cancer. Thus in this work radiolabeling of monoclonal anti-EGFR with ⁹⁰Y for radioimmunotherapy (RIT) is targetted. Cetuximab was successively labeled with [⁹⁰Y] chloride (74 MBq) 2 mCi after conjugation with macrocyclics bifunctional chelating agent, 1,4,7,10-tetraazacyclododecane-N,N′,N″,N″′-tetraacetic acid mono-(N-hydroxysuccinimidyl) ester (DOTA-NHS), purified and concentrated by centrifugation using an Amicon Ultra-15 filter (Millipore, MWCo, 30000). ⁹⁰Y chloride was obtained by ⁹⁰Sr/⁹⁰Y generator. Radiolabeling was completed in 2 h by the addition of DOTA-cetuximab conjugate at 42 °C. The stability of radiolabeled was studied in human serum. Biodistribution studies in normal rats were carried out to determine the radioimmunoconjugate distribution up to 96 h. Radiochemical purity of 92 % (using ITLC) was obtained for final radioimmunoconjugate (Specific activity = 0.55 GBq/mg). Stability of radiolabeled protein in presence of human serum was tested at 37 °C for up to 24 h. Biodistribution studies demonstrated the highest ID/g % in the blood (2.62 ± 0.005 at 24 h) and the liver (2.19 ± 0.001). This study demonstrated that ⁹⁰Y-DOTA-cetuximab is a potential compound for the treatment of EGFR-expressing cancers.     

Preparation and biodistribution of99mTc-HT18

The preparation of N₁-(octadecylcarbomyl-methy)-ethylenediaminetriacetic acid labelled with^99mTc is described. Reduction of technetium was made using sodium borohydride (procedure A) or stannous chloride (procedure B), and the labelling efficiency was checked by thin layer chromatography. Preliminary studies of biol-behavior of this complex were performed in white rats.     

Synthesis, characterization, and saccharide binding studies of bile acid-porphyrin conjugates

Synthesis and characterization of bile acid-porphyrin conjugates (BAPs) are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studies clearly showed absorbance changes, suggesting quite high if non-selective binding, the mass spectral studies do not unambiguously support these results.     

Preparation and biodistribution of 131I-labeled graphene quantum dots

Uranium sorption from commercial phosphoric acid was carried out onto kaolinite and metakaolinite. The different factors affecting uranium adsorption have been investigated. The obtained results show that, the sorption process is applicable for the high strength phosphoric acid, 40% P₂O₅, and diluted phosphoric acid, 20% P₂O₅, but it preferred to the diluted phosphoric acid. The kinetic models applied to the sorption rate data were evaluated for Lagergren first order and the pseudo second order models. From the results, the uranium sorption from commercial phosphoric acid, 40% P₂O₅, onto kaolinite and metakaolinite was found to occur through physical sorption process.     

Preparation,characterization and biodistribution of salicylidene- and pyridoxylidene-thyroxine complexes of technetium-99m

New Schiff bases, salicylidene- and pyridoxylidene-thyroxine have been prepared and characterized. They were labeled with^99mTc. The labeling yield of the Schiff bases was over 95%. About 60% of the activity was bound to -globulin and albumin fractions when the labled compounds were incubated with a serum sample. The labeled compounds, after i.v. administration to rats, rapidly cleared from blood and excreted into the small intestine. They appeared to behave as hepatobiliary agents.     

Radioiodination and biodistribution of the monoclonal antibody TU-20 and its scFv fragment

The ability of the monoclonal antibody TU-20 and its scFv fragment to bind specifically to the C-end of the class III β-tubulin makes these substances useful as potential diagnostics for neurodegenerative diseases—especially peripheral neuropathies. TU-20 and its scFv were labeled with ¹²⁵I and ¹²³I by chloramine-T (with radiochemical yield 75 and 50%, respectively). Radiochemical purity and stability was revealed by gel filtration (decrease to 80 and 50% in 2 months, respectively). Immunoreactivity of the labeled TU-20 was determined by ELISA—the range of the preserved immunoreactivity varies from 60 to 95% in accordance to the used radiolabeling process. RIA and affinity coupling analytic methods were specifically designed with focusing on specifics of the antibody and its fragment. The results of RIA differ in depandance on the type of the reaction vessel (glass or polystyrene) and the affinity coupling results depend on the experimental arrangement—in the batch or on the column. Fragmentation of the labeled antibody and its fragment was estimated by bis–tris gel electrophoresis followed by silver staining and autoradiography (over 95% of radioactivity bound in the substances). The antibody binding in tissue slices was studied in vitro by immunohistochemistry. The Purkinje cells were observed conjugated with the radiolabeled substances, either TU-20 or its ScFv fragment in the area of the cerebellum. In vivo biodistribution of ¹²⁵I-TU-20, ¹²⁵I-scFv TU-20, ¹²³I-scFv TU-20 and Na¹²⁵I was proceeded in normal mice (wild type C57B/6/J). Both biomolecules labeled by ¹²³I were also proved in an imaging biodistribution study with use of the SPECT camera. Finally, a transgene population G93A1 Gur was used for comparative study to show the different behaviour of the substances in a normal mouse and in the modified organism with amyotrophic lateral sclerosis. The most part of differences is observed in the area of the muscles, rostal and caudal spinal cord. In summary, the monoclonal antibody TU-20 and its scFv were successfully radioiodinated and afterwards analysed by several quality control methods and biodistribution studies which confirmed their preserved or expected immunoanalytical characteristics in normal and genetically modified organism.     

Mannose-pepstatin conjugates as targeted inhibitors of antigen processing

The molecular details of antigen processing, including the identity of the enzymes involved, their intracellular location and their substrate specificity, are still incompletely understood. Selective inhibition of proteolytic antigen processing enzymes such as cathepsins D and E, using small molecular inhibitors such as pepstatin, has proven to be a valuable tool in investigating these pathways. However, pepstatin is poorly soluble in water and has limited access to the antigen processing compartment in antigen presenting cells. We have synthesised mannose-pepstatin conjugates, and neomannosylated BSA-pepstatin conjugates, as tools for the in vivo study of the antigen processing pathway. Conjugation to mannose and to neomannosylated BSA substantially improved the solubility of the conjugates relative to pepstatin. The mannose-pepstatin conjugates showed no reduction in inhibition of cathepsin E, whereas the neomannosylated BSA-pepstatin conjugates showed some loss of inhibition, probably due to steric factors. However, a neomannosylated BSA-pepstatin conjugate incorporating a cleavable disulfide linkage between the pepstatin and the BSA showed the best uptake to dendritic cells and the best inhibition of antigen processing.     

Preparation of synthetic auxin-amino acid conjugates

Auxin amide conjugates are regulators of the most important auxin, indole-3-acetic acid (IAA), which is considered responsible for many important processes within the plants. Herein, amide conjugates of IAA were synthesized employing a simple and efficient coupling method with WSCI·HCl, a water-soluble condensing reagent, in the presence of 1-hydroxybenzotriazole. IAA conjugates with 10 amino acids along with their corresponding methyl esters were prepared in excellent yields, up to 95%, aiming to facilitate their identification in plant species. Eight IAA-amino acid methyl ester conjugates are characterized here for the first time.     

UPLC-MS/MS performing pharmacokinetic and biodistribution studies of rhein

Rhein, an important constituent of Radix et Rhizoma Rhei, has been used to alleviate liver and kidney damage. In this work, plasma pharmacokinetic and biodistribution characteristics of rhein after oral administration was investigated using a rapid and sensitive ultra-performance liquid chromatography coupled to tandem high-definition mass spectrometry (UPLC-MS/MS) method. Mass spectrometry was performed on a Waters Micromass high-definition technology with an electrospray ionization source in positive ion mode. Biosamples were prepared using methanolic precipitation and the separation of rhein was achieved on a UPLC HSS T3 column by linear gradient elution and the total run time was only 4.70 min. Data were analyzed and estimated by compartmental methods using WinNonlin Professional version 5.1. Mean pharmacokinetic parameters following single-dose administration of rhein was consistent with a two-compartmental open model. It was found that rhein was distributed and eliminated rapidly in rats and the biodistribution showed the higher levels were in liver, spleen, kidney, heart, lung and the lower level observed in the muscle, adrenal, and thyroid. It was not discovered in brain and showed that rhein could not cross the blood-brain barrier. Our developed UPLC-MS/MS approach was capable of providing complete pharmacokinetic and biodistribution parameters for rhein when administered orally.     

Preparation, structural, and optical features of two-dimensional cross-linked DNA/gold-nanoparticle conjugates

The formation and the optical features of two-dimensional aggregates formed by DNA-directed immobilization and cross-linking of bifunctional DNA–gold nanoparticles at flat gold substrates are analyzed. The samples are structurally characterized by atomic force microscopy to evaluate the particle size, the particle densities, and the degree of aggregation. The optical characteristics determined by UV/visible measurements are correlated with the structural features observed.

Synthesis and photophysical studies of phthalocyanine-gold nanoparticle conjugates

This work reports on the synthesis, characterization and photophysical studies of phthalocyanine-gold nanoparticle conjugates. The phthalocyanine complexes are: tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyanine (3), 2,9,17,23-tetrakis-[(1, 6-hexanedithiol) phthalocyaninato]zinc(II) (8) and [8,15,22-tris-(naptho)-2(amidoethanethiol) phthalocyanato] zinc(II)(10). The gold nanoparticles were characterized using transmission electron microscopy, X-ray diffraction, atomic force microscopy and UV-vis spectroscopy where the size was confirmed to be ～5 nm. The phthalocyanine Au nanoparticle conjugates showed lower fluorescence quantum yield values with similar fluorescence lifetimes compared to the free phthalocyanines. The Au nanoparticle conjugates of 3 and 10 also showed higher triplet quantum yields of 0.69 to 0.71, respectively. A lower triplet quantum yield was obtained for the conjugate compared to free phthalocyanine for complex 8. The triplet lifetimes ranged from 70 to 92 μs for the conjugates and from 110 to 304 μs for unbound Pc complexes.     

Preparation of short-lived radioisotope167Tm and its biodistribution in mice

A method for the production of¹⁶⁷Tm using the¹⁶⁵Ho(,2n)¹⁶⁷Tm nuclear reaction and extraction-chromatography is described. The chemical recovery of Ho is >90%. The final product contains <4 g/ml of Ho with a radiochemical purity of >99% suitable for medical use. The estimated yield of¹⁶⁷Tm is 10–20 Ci/A·h which is comparable with other recent work. Biodistributions of¹⁶⁷Tm-citrate in mice indicate that¹⁶⁷Tm is an ideal bone and liver tumor scanning agent.     

Labeling of famotidine with 99mTc and biodistribution studies on rats

Famotidine, a gastrointestinal drug was labeled with ^99mTc and its radiopharmaceutical potential was observed on male Albino Wistar rats. Labeling yield was over 95%. Average specific activity and n-octanol/water partition coefficient (lipophilicity) were approximately 74 MBq/mg-0.66 GBq/mg and 3.4, respectively. Biodistribution studies were performed on Albino Wistar rats. The activity per gram tissue was calculated and time-activity curves were generated. The majority of the activity was observed in stomach, small intestines and kidneys. Liver and kidneys showed lower uptake compared to other H₂-receptor rich tissues. Results show that ^99mTc-famotidine is H₂receptor specific. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and studies of covalently linked meso-furyl boron-dipyrromethene-ferrocene conjugates

Four meso-furyl BODIPY-ferrocene conjugates 1–4 in which one or more ferrocene groups were connected directly to BODIPY core or meso-furyl group were synthesized by coupling of appropriate bromo meso-furyl BODIPYs with α-ethynylferrocene under mild Pd(0) coupling conditions. The compounds were characterized by HR-MS mass, NMR, absorption, electrochemistry and fluorescence techniques. The absorption studies of compounds 1–4 showed charge transfer band in addition to BODIPY absorption bands indicating that the BODIPY and ferrocene moieties interact within the conjugates. On the other hand, the charge transfer band is absent in meso-phenyl BODIPY-ferrocene conjugate due to the orthogonal arrangement of ferrocene appended meso-phenyl group with BODIPY core which prevents the interaction between the two moieties. The electrochemical studies showed strong oxidation due to ferrocene moiety and reduction due to meso-furyl BODIPY unit. The compounds 3 and 4 which contain two and three ferrocenyl groups respectively were oxidized at the same potential with two and three electrons involved in the redox process. The compounds 1–4 are weakly fluorescent due to electron transfer from ferrocene unit to BODIPY unit. However, the fluorescence can be restored by oxidizing the ferrocene to ferrocenium ion which prevents the electron transfer between the two moieties. The computational studies support the experimental results.