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Development of a selective β2-adrenoceptor tracer for single photon emission tomography is important for imaging of the lungs. Iodine-125-terbutaline (125ITB) was prepared by the reaction of terbutaline with iodine-125 in the presence of chloramine-T as the oxidizing agent. The reaction was completed by incubation of the reaction mixture at 70°C for 15 minutes at pH 7. The biodistribution study in mice indicated the ability of the tracer to bind β-adrenoceptors in lungs, liver, heart, and spleen. The localization of the tracer in the lungs was high (85%/g at 60 minutes post-injection) and the highest lung/blood/g ratio was 19.8% at 60 minutes post-injection. The selectivity of the tracer for the β2-adrenoceptor was examined by blocking with both β1 and β2-adrenoceptor selective antagonists. The results showed reduction of both heart and lung uptake of the 125ITB tracer, indicating a moderate (not absolute) selectivity for the β2-adrenoceptor. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Radiolabelled nanoparticles are useful tools for biodistribution or cellular uptake studies related to the risk assessment of nanomaterials. Such studies are ideally carried out with industrially manufactured nanoparticles. Irradiation of small quantities of such nanoparticles, in the form of dry powders, with neutrons or light ions allows radiolabelling while preserving their biologically relevant properties. However, nanoparticle powders exhibit poor thermal conductivity and may overheat under irradiation. Their effective thermal conductivity is not known and conventional temperature measurement methods are difficult to apply. Reasonably accurate temperature data could be derived from post-irradiation X-ray diffraction studies on anatase ST-01 TiO-nanoparticles, with a primary particle size of 7 nm, subjected to proton beams of different intensities. The anatase-to-rutile phase transition starting at about 750 °C was identified by observing rutile peaks in X-ray diffraction patterns. The onset of growth of single diffracting TiO-domains at around 200 °C was revealed by shape analysis of the diffraction peaks. Identifying these reference temperatures allowed a calibration of the calculated temperature profile. The effective thermal conductivity in the TiO powder target was found to be close to that of air trapped in interstices of the nanoparticulate powder. This suggests that the contribution of the nanoparticles to the heat removal from the target is negligible, thus necessitating the use of thin nanoparticle layers in the target in order to facilitate cooling and prevent thermally induced alterations of the nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Angiosperms possess a retaining trans-α-xylosidase activity that catalyses the inter-molecular transfer of xylose residues between xyloglucan structures. To identify the linkage of the newly transferred α-xylose residue, we used [Xyl-3H]XXXG (xyloglucan heptasaccharide) as donor substrate and reductively-aminated xyloglucan oligosaccharides (XGO–NH2) as acceptor. Asparagus officinalis enzyme extracts generated cationic radioactive products ([3H]Xyl·XGO–NH2) that were Driselase-digestible to a neutral trisaccharide containing an α-[3H]xylose residue. After borohydride reduction, the trimer exhibited high molybdate-affinity, indicating xylobiosyl-(1→6)-glucitol rather than a di-xylosylated glucitol. Thus the trans-α-xylosidase had grafted an additional α-[3H]xylose residue onto the xylose of an isoprimeverose unit. The trisaccharide was rapidly acetolysed to an α-[3H]xylobiose, confirming the presence of an acetolysis-labile (1→6)-bond. The α-[3H]xylobiitol formed by reduction of this α-[3H]xylobiose had low molybdate-affinity, indicating a (1→2) or (1→4) linkage. In NaOH, the α-[3H]xylobiose underwent alkaline peeling at the moderate rate characteristic of a (1→4)-disaccharide. Finally, we synthesised eight non-radioactive xylobioses [α and β; (1↔1), (1→2), (1→3) and (1→4)] and found that the [3H]xylobiose co-chromatographed only with (1→4)-α-xylobiose. We conclude that Asparagus trans-α-xylosidase activity generates a novel xyloglucan building block, α-d-Xylp-(1→4)-α-d-Xylp-(1→6)-d-Glc (abbreviation: ‘V’). Modifying xyloglucan structures in this way may alter oligosaccharin activities, or change their suitability as acceptor substrates for xyloglucan endotransglucosylase (XET) activity. [Copyright &y& Elsevier]

Abstract: The chemokine receptor CXCR4 is overexpressed in a variety of cancers including breast, prostate and lung cancer. Expression is also associated with invasion and metastasis. The possibility to image and quantify CXCR4 expression in vivo would be a valuable tool in the clinic to aid treatment regimens and to potentially understand the underlying biology of metastasis. Herein we describe the synthesis and the radiolabelling of an 18F-labelled cyclic pentapeptide, [18F]CCIC-0007 designed to bind to the extracellular domains of CXCR4. Radiolabelling was performed via conjugation of [18F]fluorobenzaldehyde with an aminooxy functionalised cyclopentapeptide. Typically, starting with 1.10GBq (30mCi) of aqueous [18F]fluoride, 105MBq (2.85mCi) of the formulated tracer was obtained within 2.5h (23±8% dc rcy, 8% EOS yield). Tissue pharmacokinetic studies in mice demonstrated rapid blood clearance, together with biliary and renal elimination. [Copyright &y& Elsevier]

Abstract: Purpose: Currently, in vivo or in vitro 99mTc-radiolabelled red blood cells are the standard blood pool imaging agents. Due to risks associated with handling of blood and the problems with the current 99mTc shortage, we were interested in a long-circulating biocompatible synthetic macromolecule that would be simple to prepare and could also be used for PET imaging. Methods: A high molecular weight hyperbranched polyglycerol (HPG) of 500kDa was derivatized to coordinate radioactive gallium and to establish its labelling efficiency, stability and pharmacokinetics. Results: The resulting radiopharmaceutical in kit form was labelled rapidly within a couple of minutes at room temperature, was stable in transferrin and EDTA challenge tests, and was non-toxic in both cell viability and different hemocompatibility assays. A pharmacokinetic biodistribution study showed that the 67Ga–HPGN was confined to the blood compartment with a biological half life of 50.7h. Conclusion: 67Ga–HPGN is thus a simple to prepare blood pool imaging agent for applications where a long biological half-life is essential, i.e., the diagnosis of internal bleeding. Since radiolabelling of the same kit with 68Ga was also confirmed, we plan to evaluate it shortly as a PET blood pool imaging agent for cardiac applications. [Copyright &y& Elsevier]

Abstract: A scaled-up radiolabelling and improved post-labelling purification procedure for [68Ga]DOTATATE is reported, using a more than 1 year old SnO2-based 1850MBq 68Ge/68Ga generator (initially double-loaded with 3700MBq 68Ge) as a source of ionic 68Ga. The elution method of choice comprised elution with 0.6M HCl in a single 4mL fraction, containing up to 95% of the total eluted 68Ga activity. The unpurified fraction was directly used for labelling after pH adjustment with 2.5M sodium acetate. Labelling efficiencies were determined at 90–95°C at various reaction times and reaction volumes of up to 5.7mL, using either 30μg or 50μg DOTATATE. Only the latter amount resulted in consistently high labelling efficiency in excess of 95%. Post-labelling purification, carried out on Sep-Pak C18, showed that 50% ethanol in saline was a superior desorption eluant than 100% ethanol. The highest and most consistent decay-corrected radiochemical yields (89%) were obtained using 50μg DOTATATE and a 20min reaction time. [Copyright &y& Elsevier]

Purpose: This study investigates the effects of (111)In-oxine incorporation on human mesenchymal stem cells' (hMSC) biology and viability, and the applicability of (111)In-oxine for single-photon emission computed tomography/X-ray computed tomography (SPECT/CT) monitoring of hMSC in vivo.Procedures: HMSC were labelled with 10 Bq/cell. Cellular retention of radioactivity, cell survival, and migration were evaluated over 48 h. Metabolic activity was assessed over 14 days and the hMSC's stem cell character was evaluated. Serial SPECT/CT was performed after intra-osseous injection to athymic rats over 48 h.Results: Labelling efficiency was 25%, with 61% of incorporated (111)In remaining in the hMSC at 48 h. The radiolabelling was without effect on cell viability, stem cell character, and plasticity, whereas metabolic activity and migration were significantly reduced. Grafted cells could be imaged in situ with SPECT/CT.Conclusions: (111)In-oxine labelling moderately impaired hMSC's functional integrity while preserving their stem cell character. Combined SPECT/CT imaging of (111)In-oxine-labelled hMSC opens the possibility for non-invasive sequential monitoring of therapeutic stem cells. [ABSTRACT FROM AUTHOR]

Purpose: It is known that major histocompatibility complex class II protein HLA-DR is highly expressed in B-cell lymphomas and in a variety of autoimmune and inflammatory diseases. Therefore, a radiolabelled fully humanized IgG4 monoclonal antibody (mAb) can provide useful prognostic and diagnostic information. Aims of the present study were to radiolabel an anti-HLA-DR mAb with technetium-99m and to evaluate its binding specificity, tissue distribution and targeting potential.Procedures: For labelling, we compared a direct method, after 2-mercaptoethanol (2-ME) reduction of disulphide bonds, with a two-step labelling method, using a heterobifunctional succinimidyl-6-hydrazinonicotinate hydrochloride chelator. Several in vitro quality controls and in vivo experiments in mice were performed.Results: We obtained highest labelling efficiency (LE, >98%) and specific activity (SA; 5,550 MBq/mg) via the direct method. In vitro quality control showed good stability, structural integrity and retention of the binding properties of the labelled mAb. The biodistribution in mice showed high and persistent uptake in spleen and suggests kidney and liver-mediated clearance pathways. In tumour targeting experiments, we observed high uptake in HLA-DR-positive xenografts compared to controls. In vivo binding was proportional to the number of injected cells. In the in vivo blocking assay, uptake of radiolabelled mAb was significantly decreased in mice pre-injected with 100-fold molar excess of unlabelled mAb.Conclusion: We efficiently labelled a humanized anti-HLA-DR mAb with (99m)Tc using a direct labelling method. Radiolabelled mAb binds to human HLA-DR antigens and therefore warrants further evaluation as a prognostic and diagnostic tool for patients with lymphoma or autoimmune diseases. [ABSTRACT FROM AUTHOR]

Abstract: An 18F-labelled 2,5-diaryl tetrazole reagent has been prepared and reacted with substituted alkene dipolarophiles through a photoactivated 1,3-dipolar cycloaddition reaction. The radiobioconjugation reaction furnished the desired product in 5 min with radiochemical conversions of 85–95% at room temperature. Remarkably, for the activated dipolarophiles, these results were obtained in highly dilute solutions (10–100 μM). [Copyright &y& Elsevier]

We present in this article an outline of some cyclotron-based irradiation techniques that can be used to directly radiolabel industrially manufactured nanoparticles, as well as two techniques for synthesis of labelled nanoparticles using cyclotron-generated radioactive precursor materials. These radiolabelled nanoparticles are suitable for a range of different in vitro and in vivo tracing studies of relevance to the field of nanotoxicology. A basic overview is given of the relevant physics of nuclear reactions regarding both ion-beam and neutron production of radioisotopes. The various issues that determine the practicality and usefulness of the different methods are discussed, including radioisotope yield, nuclear reaction kinetics, radiation and thermal damage, and radiolabel stability. Experimental details are presented regarding several techniques applied in our laboratories, including direct light-ion activation of dry nanoparticle samples, neutron activation of nanoparticles and suspensions using an ion-beam driven activator, spark-ignition generation of nanoparticle aerosols using activated electrode materials, and radiochemical synthesis of nanoparticles using cyclotron-produced isotopes. The application of these techniques is illustrated through short descriptions of some selected results thus far achieved. It is shown that these cyclotron-based methods offer a very useful range of options for nanoparticle radiolabelling despite some experimental difficulties associated with their application. For direct nanoparticle radiolabelling, if care is taken in choosing the experimental conditions applied, useful activity levels can be achieved in a wide range of nanoparticle types, without causing substantial thermal or radiation damage to the nanoparticle structure. Nanoparticle synthesis using radioactive precursors presents a different set of issues and offers a complementary and equally valid approach when laboratory generation of the nanoparticles is acceptable for the proposed studies, and where an appropriate radiolabel can be incorporated into the nanoparticles during synthesis. [ABSTRACT FROM AUTHOR]

Purpose: The ∼15 kDa variable domains of camelid heavy-chain-only antibodies (called Nanobodies®) have the flexibility to be formatted as monovalent, monospecific, multivalent or multispecific single chain proteins with either fast or slow pharmacokinetics. We report the evaluation of the fast kinetic anti-epidermal growth factor receptor (EGFR) Nanobody 7D12, labelled with Ga via the novel bifunctional chelate (BFC) p-isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS). Df-Bz-NCS has recently been introduced as the chelate of choice for Zr immuno-positron emission tomography (PET). Methods: Nanobody 7D12 was premodified with Df-Bz-NCS at pH 9. Radiolabelling with purified Ga was performed at pH 5.0-6.5 for 5 min at room temperature. For in vitro stability measurements in storage buffer (0.25 M NaOAc with 5 mg ml gentisic acid, pH 5.5) at 4°C or in human serum at 37°C, a mixture of Ga and Ga was used. Biodistribution and immuno-PET studies of Ga-Df-Bz-NCS-7D12 were performed in nude mice bearing A431 xenografts using Zr-Df-Bz-NCS-7D12 as the reference conjugate. Results: The Df-Bz-NCS chelate was conjugated to Nanobody 7D12 with a chelate to Nanobody molar substitution ratio of 0.2:1. The overall Ga radiochemical yield was 55-70% (not corrected for decay); specific activity was 100-500 MBq/mg. Radiochemical purity of the conjugate was >96%, while the integrity and immunoreactivity were preserved. Ga-Df-Bz-NCS-7D12 was stable in storage buffer as well as in human serum during a 5-h incubation period (<2% radioactivity loss). In biodistribution studies the Ga-labelled Nanobody 7D12 showed high uptake in A431 tumours (ranging from 6.1 ± 1.3 to 7.2 ± 1.5%ID/g at 1-3 h after injection) and high tumour to blood ratios, which increased from 8.2 to 14.4 and 25.7 at 1, 2 and 3 h after injection, respectively. High uptake was also observed in the kidneys. Biodistribution was similar to that of the reference conjugate Zr-Df-Bz-NCS-7D12. Tumours were clearly visualized in a PET imaging study. Conclusion: Via a rapid procedure under mild conditions a Ga-Nanobody was obtained that exhibited high tumour uptake and tumour to normal tissue ratios in nude mice bearing A431 xenografts. Fast kinetic Ga-Nanobody conjugates can be promising tools for tumour detection and imaging of target expression. [ABSTRACT FROM AUTHOR]

Abstract: The quinoline nucleus of the previously described 4-phenylquinoline-3-carboxamides NK1 receptor ligands 7 has been transformed into either substituted or azole—(i.e., triazole or tetrazole) fused pyridine moieties of compounds 9 and 10, respectively, in order to obtain NK1 receptor ligands showing lower molecular weight or higher hydrophilicity. The program of molecular manipulations produced NK1 receptor ligands showing affinity in the nanomolar range. In particular, 4-methyl-1-piperazinyl derivative 9j showed an IC50 value of 4.8nM and was proved to behave as a NK1 antagonist blocking Sar9-SP-sulfone induced proliferation and migration of microvascular endothelial cells. Therefore, compound 9j has been labeled with [11C]CH3I (t 1/2 =20.4min, β + =99.8%) starting from the corresponding des-methyl precursor 9i using with a radiochemical yield of about 10% (not decay corrected) and a specific radioactivity>1Ci/μmol in order to be used as a radiotracer in next PET studies. [Copyright &y& Elsevier]

Abstract: Objectives: PET scintigraphy with 68Ga-labelled analogs is of increasing interest in Nuclear Medicine and performed all over the world. Here we report the characteristics of the eluate of SnO2-based 68Ge/68Ga generators prepared by iThemba LABS (Somerset West, South Africa). Three purification and concentration techniques of the eluate for labelling DOTA-TATE and concordant SPE purifications were investigated. Methods: Characteristics of 4 SnO2-based generators (range 0.4–1GBq 68Ga in the eluate) and several concentration techniques of the eluate (HCl) were evaluated. The elution profiles of SnO2-based 68Ge/68Ga generators were monitored, while [HCl] of the eluens was varied from 0.3–1.0M. Metal ions and sterility of the eluate were determined by ICP. Fractionated elution and concentration of the 68Ga eluate were performed using anion and cation exchange. Concentrated 68Ga eluate, using all three concentration techniques, was used for labelling of DOTA-TATE. 68Ga-DOTA-TATE-containing solution was purified and RNP increased by SPE, therefore also 11 commercially available SPE columns were investigated. Results: The amount of elutable 68Ga activity varies when the concentration of the eluens, HCl, was varied, while 68Ge activity remains virtually constant. SnO2-based 68Ge/68Ga generator elutes at 0.6M HCl >100% of the 68Ga activity at calibration time and ±75% after 300 days. Eluate at discharge was sterile and Endotoxins were <0.5EU/mL, RNP was always <0.01%. Metal ions in the eluate were <10ppm (in total). Highest desorption for anion purification was obtained with the 30mg Oasis WAX column (>80%). Highest desorption for cation purification was obtained using a solution containing 90% acetone at increasing molarity of HCl, resulted in a 68Ga desorption of 68±8%. With all 68Ge/68Ga generators and for all 3 purification methods a SA up to 50MBq/nmol with >95% incorporation (ITLC) and RCP (radiochemical purity) by HPLC ±90% could be achieved. Purification and concentration of the eluate with anion exchange has the benefit of more elutable 68Ga with 1M HCl as eluens. The additional washing step of the anion column with NaCl and ethanol, resulted in a lower and less variable [H+] in the eluate, and, as a result the pH in the reaction vial is better controlled, more constant, and less addition of buffer is required and concordant smaller reaction volumes. Desorption of 68Ga-DOTA-TATE of SPE columns varied, highest desorption was obtained with Baker C18 100mg (84%). Purification of 68Ga-DOTA-TATE by SPE resulted in an RNP of <10−4%. Conclusions: Eluate of SnO2-based 68Ge/68Ga generator, either by fractionated elution as by ion exchange can be used for labelling DOTA-peptides with 68Ga at a SA of 50MBq/nmol at >95% incorporation and a RCP of ±90%. SPE columns are very effective to increase RNP. [Copyright &y& Elsevier]

Abstract: Peptide receptor radionuclide therapy (PRRT) has recently expanded due to radiolabelling of DOTA-peptides, such as the somatostatin analogues [DOTA0, Tyr3]octreotate (DOTATATE). The achievement of high specific activities during procedures has been indicated as the critical factor to consent effective therapy. Several radiochemical factors may negatively impact reaction procedures such as pH, temperature and time of reaction. Our study was undertaken to explore the influence of radiochemical parameters, such as time of incubation, on reaction kinetics during the radiolabelling of DOTATATE with 90Y. Methods: Forty-five radiolabelling procedures were carried out using small volumes of yttrium-90, typically 60–78μL. At nearly constant pH and temperature two different settings of radiolabelling procedures were implemented, removing the products from the heating water bath approximately after 30min (group E, early; n=20) and after 39min (group L, later; n=25). Quality controls were performed by means of both high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). Results: Reaction kinetics for 90Y were found to a provide suitable percentage of incorporation at pH 4.5 for both groups. Reaction temperature was not different between groups E and L. A significant difference was found between the two groups in radiochemical yield, which was 95.6%±0.8 for group E and 98.2%±1.1 for group L (p<0.0001). The specific activity of the final product was 46.9MBq/nmol. Conclusion: In order to achieve optimal specific activities, pH, temperature and time of reaction necessitate careful evaluation and setting. A statistically significant difference in labelling yield was found between a set of procedures completed at 39min as compared to that executed at 30min, keep the reaction pH and temperature constant. [Copyright &y& Elsevier]

The serotonin receptor 5-HT ligand 4-[F]fluoro-N-[2-[1-(2-methoxyphenyl)-1-piperazinyl]ethyl-N-2-pyridinyl-benzamide ( p-[F]MPPF) was produced by a simplified method of Le Bars et al. Traditional oil bath heating was compared to microwave heating. Various radioanalytical methods, radio-Thin Layer Chromatography (TLC), High Pressure Liquid Chromatography (HPLC) and Mass Spectrometry (MS), were compared in the evaluation of the labelled product(s). The crude reaction mixture consisted of p-[F]MPPF and 2-4 radioactive by-products eluting after the product fraction, and the reverse-phase HPLC method failed occasionally to separate p-[F]MPPF from the radioactive by-product with close retention time. The heating method had no significant effect on the composition of labelled by-products. In LC-(ESI)-MS analysis of p-[F]MPPF the labelled product was identified with m/ z ratio of 435 ([M + H]). The other HPLC fractions were measured to have following m/ z ratios: (1) 327; 349; (675) (2) 402; 407/408; (791) and (3) 436, suggesting different kind of decomposition of the labelled product and/or the inactive precursor. The ion trap mass spectrometer was sufficient for the qualitative analysis of p-[F]MPPF. However, differentiation of by-products arising from the decomposition of p-[F]MPPF or from its precursor p-MPPNO proved to be challenging. [ABSTRACT FROM AUTHOR]

Abstract: The thermodynamic stability constants of complexes of 1,4,8,11-tetraazacyclotetradecane-1,4,8-triacetic-11-methylphosphonic acid (H5te3a1p) with La3+, Sm3+, Gd3+, Ho3+ and Lu3+ metal ions were determined by potentiometric titrations at 298.2K and with ionic strength 0.10M in N(CH3)4NO3. The complexes are formed relatively fast and the stability constants exhibited are good although lower than those found for the related ligands H4teta and H8tetp. At physiological pH the completely deprotonated complex species predominate, unlike what happens with the other mentioned ligands. The 153Sm and 166Ho complexes, 153Sm/166Ho-te3a1p, were synthesised quantitatively at pH 9 and 70°C, and have shown good in vitro stability in human serum and physiological solutions except phosphate buffer (pH 7.4). The in vivo behaviour indicated that both complexes have a similar biological pattern, showing a slow tissue clearance, slow rate of total radioactivity excretion and some in vivo instability, although with some differences in their extend. These results indicate that the replacement of one acetate pendant arm of H4teta by a methylphosphonate one does not provide promising chelators to stabilize radiolanthanides for in vivo application. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Interleukin-2 (IL-2) when radiolabelled with 99mTc has been proved useful in imaging the side of lymphocytic infiltration in patients with autoimmune disorders and plays a significant role as a T-cell imaging agent. However, the labelling procedures used so far appeared to be rather complex and laborious. The aim of present study was to develop an efficient procedure of 99mTc-labelling of recombinant human interleukin-2 (rhIL-2) via hydrazinonicotinamide (HYNIC) to develop a dry kit formulation. Methods: Various molar ratios of rhIL-2/HYNIC (from 1:2 to 1:12) were used at the conjugation step. The conjugates were purified on a PD-10 column to remove the excess of unbound HYNIC, as well as of any aggregates. The final peptide concentration was quantified by the BCA method, and the number of HYNIC molecules incorporated into a rhIL-2 molecule was determined based on the reaction with 2-sulfobenzaldehyde. The 99mTc-labelling was optimized using various amounts of HYNIC–rhIL-2, 99mTc, SnCl2, tricine and nicotinic acid (NA). Quality control included GF-HPLC, ITLC, SDS-PAGE and biological assay. Biodistribution studies were performed in Swiss mice and Wistar rats. Results: Generally, the highest radiolabelling yields were achieved when the HYNIC–rhIL-2 conjugates of ca. 2–4 HYNIC molecule substitution ratios were used. The optimal pH of the reaction medium was found to be in the range of 6.5 to 7.0. GF-HPLC analysis indicated that monomer and aggregates of 99mTc-HYNIC–rhIL-2 are formed during radiolabelling. At optimized conditions of wet radiolabelling, the 99mTc-HYNIC–rhIL-2 monomer was obtained with radiochemical purity >99%, specific activity of ca. 4 GBq/mg rhIL-2 and overall yield of ca. 65%. The two-vial freeze-dried kit was prepared: the first vial contained 30 μg HYNIC–rhIL-2, co-ligands, buffer and antioxidant; the second vial contained tricine and SnCl2. The monomer of 99mTc-HYNIC–rhIL-2 was obtained by gel chromatography on a PD-10 column. No differences between labelled and unlabelled IL2 in terms of biological activity were observed. Conclusions: Our study shows that rhIL-2 can be efficiently radiolabelled with 99mTc via HYNIC, with tricine and NA as co-ligands using a two-vial freeze-dried kit. This enables the preparation of sterile and ready-to-use 99mTc-HYNIC(tricine,NA)-rhIL-2 within 1 h. [Copyright &y& Elsevier]

Industrially manufactured titanium dioxide nanoparticles have been successfully radiolabelled with V by irradiation with a cyclotron-generated proton beam. Centrifugation tests showed that the V radiolabels were stably bound within the nanoparticle structure in an aqueous medium, while X-ray diffraction indicated that no major structural modifications to the nanoparticles resulted from the proton irradiation. In vitro tests of the uptake of cold and radiolabelled nanoparticles using the human cell line Calu-3 showed no significant difference in the uptake between both batches of nanoparticles. The uptake was quantified by Inductively Coupled Plasma Mass Spectrometry and high resolution γ-ray spectrometry for cold and radiolabelled nanoparticles, respectively. These preliminary results indicate that alterations to the nanoparticles’ properties introduced by proton bombardment can be controlled to a sufficient extent that their further use as radiotracers for biological investigations can be envisaged and elaborated. [ABSTRACT FROM AUTHOR]

Abstract: A new flow-through system for the production of [11C]phosgene, a versatile labelling agent in radiochemistry for PET, is described. Cyclotron-produced [11C]CH4 is mixed with Cl2 and converted into [11C]CCl4 by passing the mixture through an empty quartz tube at 510°C. The outflow is directed through a Sb-filled guard that takes out Cl2 and then, without intentional O2 addition, through a second empty quartz tube at 750°C, giving rise to [11C]phosgene in 30–35% radiochemical yield. [Copyright &y& Elsevier]

Abstract: Introduction: Development of new 18F-labeled tracers for positron emission tomography (PET) imaging is increasingly important. Herein, we described the synthesis of silicon analogues of [18F]fluoromisonidazole in order to develop new radiolabelled compounds for the detection of tumour hypoxic domain. Their stabilities and their in vivo biodistribution were evaluated. Methods: 18F-labeled silicon-based misonidazole analogues were synthesized by alkylating 2-nitroimidazole with alkyloxy-(3-chloropropyl)dialkyl or diarylsilane. These intermediates were labeled with [18F]F− with a mixture of K18F and Kryptofix (K222) in acetonitrile as standard condition. PET imaging was performed using a dedicated small animal PET scanner. Results: 18F-labeled silicon-based misonidazole analogues were easily synthesized in three steps. The hydrolytic and radiolytic stability of these new fluorosilanes depend on the steric hindrance at the silicon center. Indeed, partial uptake of dimethylfluorosilane [18F]2a(1-(3-(Fluorodimethylsilyl)propyl)-2-nitro-1H-imidazole) in tumor hypoxic area was observed but defluorination also appeared. Moreover, PET studies indicated that, owing to its high lipophilicity, the most stable dinaphtylfluorosilane [18F]2d is retained mainly by the lungs. Conclusion: We have described an efficient and versatile approach for the synthesis of 18F-labeled, silicon-based misonidazole analogues. PET imaging of one of these compounds revealed that hypoxia could be detected. Controlling the biodistribution of 18F-labeled silicon-based misonidazole analogues will require additional studies. [Copyright &y& Elsevier]

The intention of this publication is to give an overview on research related to conjugates of polysaccharides and peptides. Dextran, chitosan, and alginate were selected, to cover four of the most often encountered functional groups known to be present in polysaccharides. These groups are the hydroxyl, the amine, the carboxyl, and the acetal functionality. A collection of the commonly used chemical reactions for conjugation is provided. Conjugation results into distinct properties compared to the parent polysaccharide, and a number of these characteristics are highlighted. This review aims at demonstrating the applicability of said conjugates with a strong emphasis on biomedical applications, drug delivery, biosensing, and tissue engineering. Some suggestions are made for more rigorous chemistries and analytics that could be investigated. Finally, an outlook is given into which direction the field could be developed further. We hope that this survey provides the reader with a comprehensive summary and contributes to the progress of works that aim at synthetically combining two of the main building blocks of life into supramolecular structures with unprecedented biological response. [Display omitted] [ABSTRACT FROM AUTHOR]

Colloidal particle size is an important characteristic to consider when choosing a radiopharmaceutical for diagnosis and therapeutic purposes in nuclear medicine. Photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) were used to determine the particle-size distribution of 90Y- and 99mTc-labelled antimony trisulfide (Sb2S3) and tin colloids (Sn-colloid). 90Y-Sb2S3 and 99mTc-Sb2S3 were found to have a diameter of 28.92 ± 0.14 and 35.61 ± 0.11 nm, respectively, by PCS. By TEM, 90Y-Sb2S3 particles were measured to be 14.33 ± 0.09 nm. 90Y-labelled Sn colloid were found to exist with a dv(max1) of 805 nm and a dv(max2) of 2590 nm, by PCS, whereas 99mTc-Sn colloid was shown to have more than 80% of radioactive particles of approximately 910 nm by PCS. For 90Y-labelled Sb2S3 and Sn colloid, a comparison of TEM and PCS indicates that these techniques found significantly different mean diameters. TEM has an excellent resolution necessary for radiocolloid particle-sizing analysis, and it is a desirable size-measuring technique because it is more reliable than PCS. [ABSTRACT FROM AUTHOR]

We determined in situ feeding rates of three co-occurring coastal mysid species using [methyl-3H]-thymidine-labelled algal detritus ( Lessonia corrugata), NaH14CO3-labelled phytoplankton ( Isochrysis galbana) and zooplankton ( Artemia sp. nauplii). All three species showed a wide and overlapping range of feeding rates on the three food types, suggesting they were broadly omnivorous. However, selectivity studies often showed a strong preference for animal prey. Although there was an overlap in the types of food the mysids ingested, some degree of feeding niche partitioning was demonstrated. Paramesopodopsis rufa tended to be more carnivorous, Tenagomysis tasmaniae fed least on zooplankton and phytoplankton, and largely on algal detritus, and Anisomysis mixta australis ingested few zooplankters, and moderate amounts of algal detritus and phytoplankton. [ABSTRACT FROM AUTHOR]

Abstract: The radiosynthesis and the radiopharmacological characterization of [ 11 C]AL-438 as a nonsteroidal ligand for the glucocorticoid receptor (GR) is described. Radiolabeling of the corresponding desmethyl precursor 10 with [11C]MeI gave [ 11 C]AL-438 in decay-corrected radiochemical yields of 30±4% (based upon [11C]CO2) within 35min at a specific radioactivity of 10–15GBq/μmol at the end-of-synthesis. The radiopharmacological evaluation of [ 11 C]AL-438 involved biodistribution and small animal PET imaging in rats, and autoradiography studies using rat brain sections. Biodistribution studies were performed in male Wistar rats and demonstrated high radioactivity uptake in pituitary and brain. However, the inability of high dose corticosterone to block binding would suggest that the radioactivity accumulation in the brain was not receptor-mediated. [Copyright &y& Elsevier]

Abstract: For the first time, natural and synthetic humic substances were radiolabelled by azo coupling [U-14C]phenyldiazonium ions onto the aromatic fragments of their macromolecules under mild reaction conditions. The radiolabelling procedure was optimized with respect to pH, reaction temperature and the molar ratio of the humic substance to the labelling compound. The labelled humic substances were purified by precipitation or ultrafiltration. The chemical yields were in the range between 23% and 95%, and the specific radioactivities varied between 68 and 206MBq 14C per gram of the humic substance, depending on the origin of the humic substance and the purification method. With the 14C-labelled humic compounds thus obtained, we were able to detect humic substances at concentrations as low as 5μg/L. These radiolabelled compounds can be used in long-term studies because, according to size exclusion chromatography data, there are no signs of their decomposition even after 5 months of storage. [Copyright &y& Elsevier]

Abstract: A mathematical model, based on structured growth kinetics, is presented to simulate the profile of assimilated radioactive sulphur by a biofilm, after the release of calculated amounts of 35SO4 2− in the biofilm environment. The radiolabelled sulphur (35S) stands as a biomass growth indicator, thus allowing the estimation of the cellular anabolic activity (growth) profile inside the biofilm. The model predicts that the maximum rate of biomass synthesis occurs at the external layer of the biofilm. A good correlation between the model predictions and previously published experimental data is reported, indicating the applicability of the structured model to describe microbial growth in immobilized cell systems. [Copyright &y& Elsevier]

Cell-based therapy by transplantation of progenitor cells has emerged as a promising development for organ repair, but non-invasive imaging approaches are required to monitor the fate of transplanted cells. Radioactive labelling with 111In-oxine has been used in preclinical trials. This study aimed to validate 111In-oxine labelling and subsequent in vivo and ex vivo detection of haematopoietic progenitor cells. Murine haematopoietic progenitor cells (106, FDCPmix) were labelled with 0.1 MBq (low dose) or 1.0 MBq (high dose) 111In-oxine and compared with unlabelled controls. Cellular retention of 111In, viability and proliferation were determined up to 48 h after labelling. Labelled cells were injected into the cavity of the left or right cardiac ventricle in mice. Scintigraphic images were acquired 24 h later. Organ samples were harvested to determine the tissue-specific activity. Labelling efficiency was 75 ± 14%. Cellular retention of incorporated 111In after 48 h was 18 ± 4%. Percentage viability after 48 h was 90 ± 1% (control), 58 ± 7% (low dose) and 48 ± 8% (high dose) ( p<0.0001). Numbers of viable cells after 48 h (normalised to 0 h) were 249 ± 51% (control), 42 ± 8% (low dose) and 32 ± 5% (high dose) ( p<0.0001). Cells accumulated in the spleen (86.6 ± 27.0% ID/g), bone marrow (59.1 ± 16.1% ID/g) and liver (30.3 ± 9.5% ID/g) after left ventricular injection, whereas most of the cells were detected in the lungs (42.4 ± 21.8% ID/g) after right ventricular injection. Radiolabelling of haematopoietic progenitor cells with 111In-oxine is feasible, with high labelling efficiency but restricted stability. The integrity of labelled cells is significantly affected, with substantially reduced viability and proliferation and limited migration after systemic transfusion. [ABSTRACT FROM AUTHOR]

Gamma scintigraphy is an established imaging modality in the horse and is principally utilised to investigate skeletal disease using bone-seeking radiopharmaceuticals. However, depending on the radiopharmaceutical and imaging sequence, scintigraphy can be used to investigate disease in virtually any organ system. In this article the indications and validity of scintigraphy as a clinical diagnostic tool to investigate non-skeletal disease in the horse are reviewed. These indications include: investigation of dental disease, identification of inflammatory foci, vascular lesions, muscle and tendon pathology, assessment of physiological function of the lungs, gastrointestinal tract and other organs. Some of the techniques described for use in the horse have not been validated fully and as a result non-skeletal scintigraphy requires further investigation and validation using well-designed prospective studies. Such information can be used by clinicians to make informed decisions regarding the clinical and economic issues associated with a specific scintigraphic technique and may help when interpreting the results. [ABSTRACT FROM AUTHOR]

Abstract: The superelastic, shape memory alloy nitinol (∼50% nickel and ∼50% titanium) is an important medical device material used for stent applications. However, the role specific surfaces properties have in protein adsorption remain controversial. In this study the effects of nitinol wire surface roughness, hydrophobicity and elemental composition upon albumin adsorption are investigated. In particular, we demonstrate that the technique of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in the so-called surface mode can be used for the direct detection of albumin on the wire surfaces. In addition, albumin adsorbing to the wires was determined by using 125I-labelled albumin. Albumin was detected on all wire samples. Surface roughness and hydrophobicity appeared to have no effect on albumin adsorption. There was however a clear correlation between the surface nickel and oxygen concentration and the amount of albumin adsorbed. Samples with higher levels of nickel and less oxygen in the surface oxide layer of the wires showed increased albumin adsorption, which could lead to improved biocompatibility. However, nickel is a toxic substance and can cause many adverse effects on humans, and thus nitinol with a slightly enriched surface nickel concentration that does not exhibit nickel release may have potential as a medical device material. [Copyright &y& Elsevier]

Abstract: This work describes the synthesis and tumor affinity testing of 8-[123I]iodo-l-1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid [ITIC(OH)], a cyclic non-naturally occurring amino acid as an imaging probe for prostate cancer. Parameters for labelling were optimized with regard to the amount of precursor, the temperature and time. Thereafter, ITIC(OH) was evaluated in terms of its uptake in primary human PC-3 and DU-145 prostate cancer cells, followed by analysis of the underlying mechanisms of the radioactivity accumulation in tumor cells. No-carrier-added ITIC(OH) was obtained in 80±15% radiochemical yield and >98% radiochemical purity by a one-step radioiodination, using IODO-GEN as oxidant. The total synthesis time was less than 30min, and compatible with a clinical routine production. ITIC(OH) accumulated intensively in primary human prostate cancer cells. The radioactivity incorporation in tumor following a 10-min incubation at 37°C/pH 7.4 varied from 35% to 58% of the total loaded activity per 106 tumor cells (355–540 cpm/1000 cells). Inhibition experiments revealed that ITIC(OH) was taken up into tumor by an active transport different from the common amino acid carrier systems, including the sodium-dependent system A and B+,0, and the sodium-independent L- and ASC-type transporter. In contrast, the cellular incorporation was dependent on the membrane potential and correlated with the activity of the mitochondria. In conclusion, the specific and high-level accumulation of ITIC(OH) in human prostate carcinoma cells, indicates that the new radiopharmaceutical is a good candidate for further in vivo investigations to ascertain its potential as an imaging probe for prostate cancer by SPET. [Copyright &y& Elsevier]

It has long been known that the oxidative state of the various plasma lipoproteins modulates platelet aggregability, thereby contributing to atherogenesis. Low-density lipoprotein (LDL), occurring in vivo both in the native and oxidised forms, interacts directly with platelets, by binding to specific receptors. While the identity of the receptors for native LDL and some subfractions of high-density lipoproteins (HDL) remains disputed, apoE-containing HDL2 binds to LRP8. The nature of these interactions as well as the distinction between candidate receptor proteins was elucidated using covalently modified apolipoproteins, which pointed to the participation of apolipoproteins in high affinity binding. However, the platelet effects initiated by binding of native lipoproteins remain controversial. Some of this ambiguity can be traced to the fact that native LDL inevitably undergoes substantial oxidisation upon modification, including by radiolabelling. The platelet-activating effects provoked by oxidised LDL are irrefutable, but many details remain unknown. The role of CD36 in platelet binding by oxidised LDL is well established, although additional receptors may exist. Much less is known about the interaction of oxidised HDL with platelets, since platelet activation was observed in some, but not all studies. Various frequently applied in vitro oxidation methods produce modified lipoprotein species that may not be relevant in vivo. Based on the reported modifications obtained by in vitro oxidation of LDL, early investigations focused mainly on the formation and the eventual effects of oxidised lipids. More recently, alterations to lipoproteins performed using hypochloric acid and myeloperoxidase redirected the attention to the role of modified apoproteins in triggering platelet responses. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of a new fluorocarbon amphiphilic drug carrier is described. A polyfunctional amino acid endowed with a fluorocarbon chain and a sugar moiety providing the amphiphilic character constitutes the central element of this structure. A 14C-radiolabelled acetyl group was grafted onto the third function and the bioavailability of this molecule was specified in mice after IV administration. This amphiphilic drug carrier exhibits a rapid and homogeneous distribution to the whole tissues and slow elimination half-lives (higher than one day) through a biliary excretion without any toxicity (no measured DL 50 for concentrations up to 500mg/kg). [Copyright &y& Elsevier]

Purpose: Rituximab was the first chimeric monoclonal antibody to be approved for treatment of indolent B-cell non-Hodgkin's lymphoma (NHL). It is directed against the CD20 antigen, which is expressed by 95% of B-cell NHLs. The aim of this study was to explore the possibility of radiolabelling rituximab with 99mTc for use as an imaging agent in NHL for early detection, staging, remission assessment, monitoring for metastatic spread and tumour recurrence, and assessment of CD20 expression prior to (radio)immunotherapy. Methods: Rituximab was purified from Mabthera solution (Roche), photo-activated at 302 nm by UV irradiation and radiolabelled with 99mTc. The effectiveness of the labelling method was evaluated by determination of the number of free thiol groups per photoreduced antibody, radiochemical purity and in vitro stability of 99mTc-rituximab. Results: On average, 4.4 free thiol groups per photoreduced antibody were determined. Radiolabelling yields greater than 95% were routinely observed after storage of the photo-activated antibody at -80°C for 195 days. The direct binding assay showed preserved ability of 99mTc-rituximab to bind to CD20, with an average immunoreactive fraction of 93.3%. The internalisation rate was proven to be low, with only 5.3% of bound 99mTc-rituximab being internalised over 4 h at 37°C. Conclusion: Our results demonstrate that 99mTc-rituximab of high radiochemical purity and with preserved binding affinity for the antigen can be prepared by photoreduction and that the method shows good reproducibility. 99mTc-rituximab will be further explored as an imaging agent applicable in NHL for the purposes mentioned above. [ABSTRACT FROM AUTHOR]

Abstract: C-11 labelled methyl esters have been synthesized via the transesterification of enol esters in the presence of C-11 methanol and 1,3 dichlorodibutylstannoxane as catalyst. This method leaves functional groups intact and allows access to a wider variety of C-11 labelled methyl esters compared to the BF3 catalysed ester formation, which uses carboxylic acids and C-11 methanol as starting materials. [Copyright &y& Elsevier]

Background: Presently, sublingual immunotherapy is widely used as an alternative to the injection route for respiratory allergy, but its pharmacokinetics in humans is poorly known, and data are available only for Par j 1 allergen. We aimed at assessing the biodistribution of iodine-123-radiolabelled Der p 2 in allergic volunteers. Methods: Purified Der p 2 and its monomeric allergoid were radiolabelled with iodine-123 and administered sublingually to 7 allergic volunteers. The subjects were allowed to swallow 6 min after administration. Dynamic (up to 10 min) and static scintigraphic images (30 min, 1, 2, 3 and 20 h) were recorded, and blood samples were obtained at different time points to measure the plasma radioactivity and to assess the presence of circulating radiolabelled species by gel chromatography. Results: The local pharmacokinetics did not differ between allergen and allergoid. Plasma radioactivity began to increase only after swallowing and peaked at 1–2 h. Both the allergen and the allergoid persisted in the mouth for several hours, and traces could be detectable up to 20 h. At radioactivity plasma peak, gel chromatography showed that a fraction of the allergoid, but not the allergen, was absorbed as an intact molecule. Conclusions: These results indicate that the pharmacokinetics of sublingual administration is independent of the allergen used and characterized by the long persistence in the mouth. The contribution of enteric absorption of the allergoid in the mechanism of action of sublingual immunotherapy remains to be defined. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Local nasal immunotherapy is accepted as an alternative to the injection route for allergic rhinitis. Despite this, little is known about the kinetics of the allergen after nasal delivery in allergic subjects. We aimed at assessing the biodistribution of 123I-radiolabelled Par j 1 in Parietaria-allergic subjects, in comparison with healthy volunteers. Purified Par j 1 was radiolabelled with 123I and sprayed into the nostrils of three control subjects and three Parietaria-allergic volunteers. Dynamic and static scintigraphic images of the head were recorded at serial times and blood samples were obtained to measure the plasma radioactivity, and to assess the presence of circulating radiolabelled species by gel chromatography. In Parietaria-sensitized subjects, the radiolabelled allergen was rapidly cleared from the nasal cavity and transported to pharynx, and little local persistence was seen. This differed from healthy subjects where nasal clearance of the tracer was slower and nasal radioactivity persisted up to 24 h. The increase in plasma radioactivity paralleled swallowing of the allergen in both groups, and plasma chromatographic profile did not differ between allergic and healthy volunteers. Sensitization to the allergen affects its local biodistribution. Gastrointestinal absorption is relevant also for the intranasal route. [ABSTRACT FROM AUTHOR]

Purpose. A new held of interest is the application of 68Ga-labelled DOTA-conjugated peptides for positron emission tomography (PET). The commercially available or house-made generators require time-consuming and tedious handling of the eluate. Radiolabelling at high specific activities without further purification is not possible, while high specific activities are necessary br peptides that potentially display pharmacological side-effects. Here we present the practical aspects and the results of radiolabelling DOTA-peptides with a TiO2-based commercially available 68Ge/68Ga generator. Methods. Reaction kinetics and parameters influencing the incorporation of the radionuclide at the highest achievable specific activity were investigated. Since high linger doses were anticipated during handling of the high beta-energy emitter 68Ga, finger dosimetric measurements were performed during radiolabelling and in vivo administration. Results. Fractionated elution of the generator revealed that 80% of the radioactivity was recovered in 1 ml. Bi- and trivalent ionic contaminants that compete for the incorporation of the radionuclide were below 50 nM; thus further tedious and time-consuming purification was avoided. Radiolabelling was performed at pH 3.5-4. Plastic shielding (&ges; 7-mm wall thickness) around the syringe during administration effectively eliminated the positrons. In rats 68GaCl3 had slow clearance from blood, while 68Ga-EDTA was rapidly cleared via the kidneys. Uptake of 68Ga-DOTATOC in somatostatin receptor-positive tissues was high, with no significant difference between 1 and 4 h post injection. Conclusion. DOTA-peptides for PET imaging can he labelled with 68Ga up to specific activities of 1 GBq per nmol within 20 min, enabling the clinical application of peptides that display potential pharmacological side- effects. [ABSTRACT FROM AUTHOR]

Abstract: Surface functionalization of a commercially available poly(vinylidene fluoride) (PVDF) filtration membrane (Millipore DVPP) was performed using organic synthesis at the solid–liquid interface. Hydroxyl groups present on this hydrophilic membrane were activated by reaction with several activating and coupling agents prior to the covalent grafting of lysine. Transamination was used as well as a grafting method. The apparent surface of the PVDF membrane was characterized using SEM and XPS techniques before and after the wet chemical treatments. On the other hand, chemical reactivity of the open surface was assayed by the coupling to tritiated lysine and liquid scintillation counting (LSC) of the radioactivity associated to the samples. [Copyright &y& Elsevier]

Protein phosphorylation analysis is an enormous challenge. This review summarises the currently used techniques, which are based on radiolabelling and mass spectrometry as well as electrophoretic and chromatographic separation. Many methods exist, but there is still no single procedure applicable to all phosphoproteins. MS is able to deliver information about the location of phosphorylation sites, but phosphospecific properties with respect to ionisation present obstacles. Therefore, multidimensional approaches involving several analytical methods are often necessary to conquer phosphorylation site identification. [ABSTRACT FROM AUTHOR]

The surface characteristics of intravenously administered particulate drug carriers decisively influence the protein adsorption that is regarded as a key factor for the in vivo fate of the carriers. We labeled surface-modified polymer particles with the γ-emitting radioisotope 99mTc in order to test their properties in blood and follow their in vivo fate. The biodistribution was different in various types of polymer particles. As expected, labeled particles were found in the mononuclear phagocyte system in a large scale but markedly different biodistribution for some particles were also shown. [Copyright &y& Elsevier]

Radiolabelling of brain tissue has long been used to facilitate detection of transmitter efflux, on the assumption that egress of tritiated monoamines reflects that of the endogenous transmitter. The present study tested the hypothesis that the application of exogenous serotonin (5-HT) to mesencephalic slices, in the manner used during a typical radiolabelling protocol, leads to efflux of 5-HT from physiologically inappropriate loci such as other non-serotonergic neurones. We used fast cyclic voltammetry (FCV) to determine the effect of tissue pre-incubation with 5-HT on electrically-stimulated 5-HT efflux and reuptake in rat mesencephalic slices. Seven subregions were studied, including the dorsal raphe nucleus (DRN), dorsomedial periaqueductal grey (PAGdm) and the oral part of the pontine reticular nucleus (PnO). In control slices (pre-incubated without 5-HT), stimulated 5-HT efflux was only detectable in DRN, PAGdm and occasionally in PnO. In slices incubated in 5-HT (100 nM) for 30 min, stimulated 5-HT efflux was detected in all seven subregions studied. In such slices, citalopram (75 nM) increased efflux and reuptake t1/2 in DRN to 201±21 and 487±117% of pre-drug values (P<0.05) but had no significant effect on either measure in PnO. The 5-HT1 autoreceptor agonist, 5-carboxamidotryptamine (5-CT, 100 nM) decreased efflux in DRN by 54±6% (P<0.05), but was without effect (10±14%) in PnO. The present results show that pre-incubation in 5-HT allows stimulated 5-HT efflux from regions of the mesencephalon other than DRN and PAGdm. This stimulated 5-HT efflux is apparently not influenced by 5-HT transporters or 5-HT1 autoreceptors, suggesting that efflux is ectopic, an artefact of the pre-incubation process. In summary, incubation of rat mesencephalic tissue in 5-HT, in the manner of a typical radiolabelling protocol, results in stimulated 5-HT efflux from non-physiological sites. The results of such transmitter efflux studies should thus be interpreted with caution. [Copyright &y& Elsevier]

Tritium-labelled dihydro derivatives of the cyanobacterial peptide hepatotoxin nodularin were prepared by reduction with sodium boro[3H]hydride. The optimised reaction gave two dihydronodularin stereoisomers which were purified by high-performance liquid chromatography with a mobile phase of methanol–0.7% sodium sulfate (6:4) and a C18 stationary phase. The specific activities of the stereoisomers were 1780–1807 dis min−1 ng−1. The radiolabelled dihydronodularins were tested for stability and used for toxicokinetic studies in mice. Liver was the main site of toxin accumulation. [Copyright &y& Elsevier]

Radiolabelling and electrochemical impedance measurements were used to characterize the immobilization of single stranded homooligonucleotides onto silica surfaces and their subsequent hybridization with complementary strands. The immobilization procedure consists of grafting an epoxysilane onto microelectronic grade Si/SiO2 substrates, and coupling oligonucleotides bearing a hexylamine linker onto the epoxy moiety. Radiolabelling was used as a reference method to quantify the amount of immobilized and hybridized oligonucleotides. These results show that the Si/SiO2 substrates modified with an epoxysilane yield a surface concentration of ∼1011 strands/cm2 for the immobilized oligonucleotides, after vigorous washings, and that ∼36% of these undergo hybridization with complementary strands. The impedance measurements, which provide a direct means of detecting variations in electrical charge accumulation across the semiconductor/oxide/electrolyte structure when the oxide surface is chemically modified, show that the semiconductor''s flat band potential undergoes reproducible shifts of −150 and −100 mV following the immobilization and the hybridization step, respectively. These results demonstrate that electrochemical impedance measurements using chemically modified semiconductor/oxide/electrolyte structures of this type offer a viable alternative for the direct detection of complementary DNA strands upon hybridization. [Copyright &y& Elsevier]

14C-l-phenylalanine is incorporated into a range of polyphenolic compounds when fed to grape cell cultures. Optimisation of several parameters such as the quantity of precursor applied and the duration of metabolism led to incorporation yields of 15% and to specific activities of 875 μCi g−1 in stilbenes. Purification of the products by several chromatographic steps is reported. Both trans- and cis-resveratrols were easily obtained by enzymatic hydrolysis of their corresponding glucosides, with specific activity of 1200–1400 μCi g−1. The specific radioactivity obtained for all the compounds is suitable for in vivo feeding trials to trace their metabolic fate when consumed by animals and for in vitro activity mechanism studies. Indeed, these polyphenols seem to be implicated in the health benefits associated with regular and moderate wine consumption but little is known about their pharmacokinetics and cellular uptake. [Copyright &y& Elsevier]

Chlorinated polypropylene (CPO) is commonly used as an adhesion promoter for paint on polypropylene/ ethylene-propylene copolymer blends (PP/EP). An adhesion mechanism frequently proposed in the literature is the CPO diffusion into the substrate, leading to molecular entanglement. It is shown here that CPO and PP/EP are immiscible. On the other hand, the use of radiolabelled CPO allowed quantification of CPO diffusion into PP/EP substrates as a function of several parameters and under conditions which simulate industrial practice. Diffusion requires substrate swelling by the solvent. This explains that it increases with the EP content of the material, with the solvent ability to swell the substrate, and with the thickness of the paint. For baked samples, diffusion passes through a maximum when the delay between CPO application and baking is varied. This is due to a balance between two processes working in opposite directions, i.e. substrate swelling and solvent evaporation. [ABSTRACT FROM AUTHOR]