Vanadium uptake and an effect of vanadium treatment on 18 F-labeled water movement in a cowpea plant by positron emitting tracer imaging system (PETIS)

We present real time vanadate (V⁵⁺ ) uptake imaging in acowpea plant by positron emitting tracer imaging system (PETIS). Vanadium-48was produced by bombarding a Sc foil target with 50 MeV -particlesat Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) AVFcyclotron. Then ⁴⁸ V was added to the culture solution to investigatethe V distribution in a cowpea plant. The real time uptake of the ⁴⁸V was monitored by PETIS. We measured the distribution of ⁴⁸Vin a whole plant after 3, 6 and 20 hours of V treatment by Bio-imaging AnalyzerSystem (BAS). After the 20 hour treatment, vanadate was detected at the up-groundpart of the plant. To know the effect of V uptake on plant activity, ¹⁸F-labeled water uptake was analyzed by PETIS. When a cowpea plantwas treated with V for 20 hours before ¹⁸ F-labeled water uptakeexperiment, the total amount of ¹⁸F-labeled water absorption wasdrastically decreased. Results suggest the inhibition of water uptake wasmainly caused by the vanadate already moved to the up-ground part of the plant.     

Uranium isotopes as a tracer of groundwater transport studies

The activity concentrations of ²³⁴U and ²³⁸U in thermal groundwater, deep well water and river water samples from Central Poland were determined. Concentration of ²³⁴U and ²³⁸U in the examined waters varied from <0.013 (LLD) to 16.8 mBq/dm³ and from <0.013 (LLD) to 45.5 mBq/dm³ respectively. The highest uranium activity concentrations were measured in the thermal groundwater from Mszczonow and Cieplice, while the lowest were observed in thermal ground water from Uniejow and Poddebice. In thermal groundwater from Skierniewice, uranium activity concentrations were below lower limit of detection (0.013 mBq/dm³). The ²³⁴U/²³⁸U activity ratio varied from 0.37 (Cieplice) to 1.30 (Poddebice well water).     

Water movement in a plant sample by neutron beam analysis as well as positron emission tracer imaging system

We present water imaging of a plant sample both by neutron beam and positron emission tracer imaging system (PETIS). The former method provided static water profile in a plant sample as well as that in the vicinity of a root imbedded in soil. Not only X-ray film but also CT method using a cooled CCD camera is presented. Through non-destructive water image in an X-ray film, root development as well as 2-dimensional water movement toward the root was analyzed. Spatial water image was constructed from 180 CT projection images, taken at an interval of one degree while rotating the sample, through a CCD camera. In the case of a soybean root, there was a water gradient toward a root in soil and gave minimum value at about 1 mm far from the surface of a root. The water absorbing part in a root was gradually shifted downward with the root development. We also present real time water movement by PETIS, where water was labeled with a positron emitting nuclide, ¹⁵O. The transportation of ¹⁵O-water within a plant was relatively slow and water uptake was observed only at the lowest internode, between a root and the first leaf, during 20-minute measurement.     

The fluoride content of an anion exchange resin in the fluoride form. Determinations using18F as a tracer

The fluoride content of an anion exchange resin in the F⁻-form depends on the material of the equipment used for the preparation. If a glass equipment is used too much fluorine is introduced, but in a teflon equipment the fluoride content is exactly as expected. The experimental results are explained by taking into account a competition of F⁻ and SiF ₆ ⁻² for the hydroxyl positions of the resin(OH⁻).     

Production of18F with an18O enriched water target

A target system for the production of nucleophilic 110-min¹⁸F from isotopically enriched /¹⁸O/H₂O is described. The process occurs via the nuclear reaction¹⁸O/p,n/¹⁸F, the available proton beam of 72 MeV must be degraded to the entrance energy of 15 MeV. This process is in regular use for the batch production of 0.8–1 Ci¹⁸F.     

Silicon-based chemistry: an original and efficient one-step approach to [18F]-nucleosides and [18F]-oligonucleotides for PET imaging

Take it eaSi! Nucleosides, dinucleotides, and one oligonucleotide, all modified by click chemistry, have for the first time been directly and very efficiently labeled with (18)F by using a silicon-based, one-step approach that opens the way for the development of a new class of positron emission tomography (PET) tracers (see graphic).     

HTO as a conservative tracer used for characterization of contaminant migration in porous rock environment

Methodology for diffusion coefficient determination was applied on sandstone samples, using conservative non sorbing tracer. The results proved that methodology, through-diffusion cell design and GoldSim diffusion module can be used for sandstone samples in order to determine important migration parameters, necessary for transport model input. However, rock heterogeneity factor has to be taken into account in any case as it can potentially change rock properties, even within centimeter scale. Effective diffusion coefficient D _e for rock samples was determined. The values fell into the range of 1.0–6.17 × 10⁻¹⁰ m² s⁻¹. Discrepancies in measured and simulated porosity were observed. Statistical analyses revealed that values of diffusion coefficient D _e were in close interrelation to primary mineral (quartz) and cement forming minerals (kaolinite and organic matter).     

Silicon-containing compounds as bases of drugs used to regulate plant growth

Methods for obtaining physiologically active silicon-containing compounds are developed. Silatrane and silocane derivatives of o-cresol, o-cresoxyacetic, and methacrylic acids are obtained. A comparative study of the toxic effects of silatranes and silocanes is performed. Tests on plant growth are carried out. The wound-healing effects are studied.     

Synthesis of O-(2-[~(18)F]fluoroethyl)-L-tyrosine and its biological evaluation in B16 melanoma-bearing mice as PET tracer for tumor imaging

O-(2-[18F]fluoroethyl) -L-tyrosine([18F]FET) ,a fluorine-18 labeled analogue of tyrosine,has been syn-thesized and biologically evaluated in tumor-bearing mice. The whole synthesis procedure is com-pleted within 50 min. The radiochemical yield is about 40%(no decay corrected) and radiochemical purity more than 97% after simplified solid phase extraction. [18F]FET shows rapid,high uptake and long retention in the tumor as well as low uptake in the brain. The ratios of tumor-to-muscle(T/M) and tumor-to-blood(T/B) of [18F]FET are similar to those of [18F]FDG,but the ratios of tumor-to-brain(T/Br) are 2-3 times higher than that of [18F]FDG. Autoradiography of [18F]FET demonstrates a remarkable accumulation in melanoma with high contrast. It appears to be a probable competitive candidate for melanoma imaging with PET.     

Bound and free water distribution in wood during water uptake and drying as measured by 1D magnetic resonance imaging

Knowledge on moisture transport in wood is important for understanding its utilization, durability and product quality. Moisture transport processes in wood can be studied by Nuclear Magnetic Resonance (NMR) imaging. By combining NMR imaging with relaxometry, the state of water within wood can be identified, i.e. water bound to the cell wall, and free water in the cell lumen/vessel. This paper presents how the transport of water can be monitored and quantified in terms of bound and free water during water uptake and drying. Three types of wood from softwood to hardwood were selected covering a range of low to high density wood; pine sapwood and oak and teak. A calibration is performed to determine the different water states in each different wood type and to convert the NMR signal into moisture content. For all wood types, water transport appeared to be internally limited during both uptake and drying. In case of water uptake, free water was observed only after the cell walls were saturated with bound water. In case of drying, the loss of bound water starts only after vanishing of free water, irrespective of the position. Obviously, there is always a local thermodynamic equilibrium of bound and free water for both uptake and drying. Finally, we determined the effective diffusion coefficient (D _eff ). Experimentally determined diffusion constants were compared with those derived by the diffusion models for conceptual understanding of transport mechanism. We found that diffusion in the cell wall fibers plays a critical role in the transport process.     

Sequential extraction as a tool to study the foliar uptake of radionuclides

In order to study the foliar uptake of radionuclides deposited from an aerosol released in an accidental situation, lettuce plants were contaminated with an aerosol containing⁸⁵Sr,¹³⁴Cs and^110mAg isotopes. The methodology chosen to carry out this study is based on a sequential extraction scheme using water, to evaluate the fraction possibly removed by rain or by washing, and an organic solvent, to distinguish between the fraction adhering to the cuticle and the one incorporated in the leaves. Two procedures are compared. Moreover, the different behavior of the radionuclides in their incorporation into the leaves is deduced from the results obtained.     

Radiosynthesis of 10-(2-[18F]fluoroethoxy)-20(S)-camptothecin as a potential positron emission tomography tracer for the imaging of topoisomerase I in cancers

The preparation of 10-(2-[¹⁸F]fluoroethoxy)-20(S)-camptothecin, a potential positron emission tomography tracer for the imaging of topoisomerase I in cancers, is described. 10-(2-[¹⁸F]Fluoroethoxy)-20(S)-camptothecin was synthesized by the [¹⁸F]fluoroalkylation of the corresponding hydroxy precursor molecule with 2-[¹⁸F]fluoroethyl bromide ([¹⁸F]FEtBr) in dimethylsulfoxide (DMSO) at 55 °C for 20 min; this was followed by purification using high performance liquid chromatography (HPLC) with a total preparation time of 60 min. The overall radiochemical yield was approximately 5.4–12 % (uncorrected), and the radiochemical purity was above 96 %.     

Production of no-carrier-added 64Cu and applications to molecular imaging by PET and PETIS as a biomedical tracer

Copper-64 was produced by the ⁶⁴Ni(p, n)⁶⁴Cu reaction using enriched ⁶⁴NiO target. We investigated and compared the production yield of ⁶⁴Cu for proton beams of various energies by using a thick target. Enriched ⁶⁴Ni was recovered with high yield by simple procedures. Imaging studies using positron emission tomography (PET) and positron emitting tracer imaging system (PETIS) were performed. We obtained clear images in PET and PETIS studies. The results of this study indicate that ⁶⁴Cu can be utilized as a biomedical tracer for the molecular imaging both in animals and plants.     

Beryllium-7 as a tracer of stratospheric ozone: A case study

A new method is presented for the determination of Au and Pt in biological materials based on neutron activation analysis with radiochemical separation of gold. Separation of gold by electrolytic deposition on a niobium cathode ascertains the highest radiochemical purity without any interference from calcium or other major elements. With¹⁹⁹Au as indicator for platinum the gold content of the sample not only strongly affects the limit of detection, but also causes interference by double neutron capture. Replicate analyses of BCR Certified Reference Materials No. 184, 185 and 186 were carried out.Presented at the MTAA-8 Conference, September 16–20, 1991, Vienna, Austria.     

[18F]Ethenesulfonyl Fluoride as a Practical Radiofluoride Relay Reagent

Fluorine-18 is the most utilized radioisotope in positron emission tomography (PET), but the wide application of fluorine-18 radiopharmaceuticals is hindered by its challenging labelling conditions. As such, many potentially important radiotracers remain underutilized. Herein, we describe the use of [¹⁸F]ethenesulfonyl fluoride (ESF) as a novel radiofluoride relay reagent that allows radiofluorination reactions to be performed in minimally equipped satellite nuclear medicine centres. [¹⁸F]ESF has a simple and reliable production route and can be stored on inert cartridges. The cartridges can then be shipped remotely and the trapped [¹⁸F]ESF can be liberated by simple solvent elution. We have tested 18 radiolabelling precursors, inclusive of model and clinically used structures, and most precursors have demonstrated comparable radiofluorination efficiencies to those obtained using a conventionally dried [¹⁸F]fluoride source.     

New technique to trace [<Superscript>15</Superscript>O]water uptake in a living plant with an imaging plate and a BGO detector system

Summary We present a new trial to measure real time water movement in a living plant using the positron emitting radionuclide, ¹⁵O. ¹⁵O was prepared by ¹⁴N(d,n)¹⁵O reaction and 10 ml of ¹⁵O labeled water (2 GBq) was supplied from the root of a soybean plant. To detect activity, an imaging plate (IP) as well as a BGO detector system were used. Since the half-life of ¹⁵O is extremely short, (T_1/2= 122 s), water uptake measurement was performed only for 20 minutes. In order to get [¹⁵O]waterimage, an IP was exposed to the plant for 1 minute for two times. Since the exposure to an IP requires dark condition, a BGO detector system was developed to measure [¹⁵O]waterunder light condition. A couple of BGO probes was set at the lowest stem and the gamma-rays (0.511 MeV) emitted from the radionuclide were measured through coincidence counting and compared with the radioactivity measured from an IP image. Using this system, we have found that the water uptake activity of the plant was drastically reduced under high humidity (99%) and dark condition.