Targeting GRPR in urological cancers--from basic research to clinical application

Gastrin releasing peptide (GRP) is a regulatory peptide that acts through its receptor (GRPR) to regulate physiological functions in various organs. GRPR is overexpressed in neoplastic cells of most prostate cancers and some renal cell cancers and in the tumoral vessels of urinary tract cancers. Thus, targeting these tumours with specifically designed GRP analogues has potential clinical application. Potent and specific radioactive, cytotoxic or nonradioactive GRP analogues have been designed and tested in various animal tumour models with the aim of receptor targeting for tumour diagnosis or therapy. All three categories of compound were found suitable for tumour targeting in animal models. The cytotoxic and nonradioactive GRP analogues have not yet shown convincing tumour-reducing effects in human trials; however, the first clinical studies of radioactive GRP analogues--both agonists and antagonists--suggest promising opportunities for both diagnostic tumour imaging and radiotherapy of prostate and other GRPR-expressing cancers.

Early over-expression of GRP receptors in prostatic carcinogenesis

BACKGROUND The GRP receptor shows high over-expression in prostatic adenocarcinoma and high grade PIN, but low expression in normal prostate glands. This represents the molecular basis for GRP receptor imaging of prostate cancer with radioactive compounds. However, a focal, high density GRP receptor expression can be observed in hitherto uncharacterized prostate glands. METHODS GRP receptors were quantitatively measured with in vitro receptor autoradiography using ¹²⁵I-Tyr⁴ -bombesin in samples from 115 prostates. On successive tissue sections, ¹²⁵I-Tyr⁴ -bombesin autoradiography was compared with H&E staining and MIB-1 and 34βE12 immunohistochemistry. RESULTS On one hand, it was confirmed that GRP receptors were expressed in adenocarcinoma and high grade PIN in high density and high incidence (77% and 73%, respectively), but in normal prostate glands in low density and low frequency (18%). On the other hand, a novel and intriguing observation was the existence of focal non-invasive prostate glands with high GRP receptor density, characterized by low grade nuclear atypia and increased proliferation, compatible with lower grade PIN. There was a significant GRP receptor density gradient (P ≤ 0.005), increasing from normal prostate glands (mean relative optical density, ROD, of ¹²⁵I-Tyr⁴ -bombesin binding: 0.17) over atypical glands without increased MIB-1 labeling (0.28) and atypical glands with increased MIB-1 expression (0.44) to high grade PIN and adenocarcinoma (0.64 and 0.58, respectively). CONCLUSIONS GRP receptor over-expression may be a novel, specific marker of early prostatic neoplastic transformation, arising in low grade PIN, and progressively increasing during malignant progression. This should be considered when interpreting in vivo GRP receptor imaging in males.

Solute transport in crystalline rocks at Äspö — II: Blind predictions, inverse modelling and lessons learnt from test STT1

Based on the results from detailed structural and petrological characterisation and on up-scaled laboratory values for sorption and diffusion, blind predictions were made for the STT1 dipole tracer test performed in the Swedish A¨ spo¨ Hard Rock Laboratory. The tracers used were nonsorbing, such as uranine and tritiated water, weakly sorbing 22Na+, 85Sr2 +, 47Ca2 +and more strongly sorbing 86Rb+, 133Ba2 +, 137Cs+. Our model consists of two parts: (1) a flow part based on a 2D-streamtube formalism accounting for the natural background flow field and with an underlying homogeneous and isotropic transmissivity field and (2) a transport part in terms of the dual porosity medium approach which is linked to the flow part by the flow porosity. The calibration of the model was done using the data from one single uranine breakthrough (PDT3). The study clearly showed that matrix diffusion into a highly porous material, fault gouge, had to be included in our model evidenced by the characteristic shape of the breakthrough curve and in line with geological observations. After the disclosure of the measurements, it turned out that, in spite of the simplicity of our model, the prediction for the nonsorbing and weakly sorbing tracers was fairly good. The blind prediction for the more strongly sorbing tracers was in general less accurate. The reason for the good predictions is deemed to be the result of the choice of a model structure strongly based on geological observation. The breakthrough curves were inversely modelled to determine in situ values for the transport parameters and to draw consequences on the model structure applied. For good fits, only one additional fracture family in contact with cataclasite had to be taken into account, but no new transport mechanisms had to be invoked. The in situ values for the effective diffusion coefficient for fault gouge are a factor of 2–15 larger than the laboratory data. For cataclasite, both data sets have values comparable to laboratory data. The extracted Kd values for the weakly sorbing tracers are larger than Swedish laboratory data by a factor of 25–60, but agree within a factor of 3–5 for the more strongly sorbing nuclides. The reason for the inconsistency concerning Kds is the use of fresh granite in the laboratory studies, whereas tracers in the field experiments interact only with fracture fault gouge and to a lesser extent with cataclasite both being mineralogically very different (e.g. clay-bearing) from the intact wall rock.

Transport of 234U in the Opalinus Clay on centimetre to decimetre scales

The Opalinus Clay formation in North Switzerland is a potential host rock for a deep underground radioactive waste repository. The distribution of U-238, U-234 and Th-230 was studied in rock samples of the Opalinus Clay from an exploratory borehole at Benken (Canton of Zurich) using MC-ICP-MS. The aim of U-234 was to assess the in situ, long-term migration behaviour in this rock. Very low hydraulic conductivities of the Opalinus Clay, reducing potential of the pore water and its chemical equilibrium with the host rock are expected to render both U-238 and Th-230 immobile. If U is heterogeneously distributed in the Opalinus Clay, gradients in the supply of U-234 from the rock matrix to the pore water by the decay of U-238 will be established. Diffusive redistribution separates U-234 from its immobile parent U-238 resulting in bulk rock U-234/U-238 activity disequilibria. These may provide a means of estimating the mobility of U-234 in the rock if the diffusion rate of U-234 is significant compared to its decay rate. Sampling was carried out on two scales. Drilling of cm-spaced samples from the drill-core was done to study mobility over short distances and elucidate possible small-scale lithological control. Homogenized 25-cm-long portions of a 2-m-long drill-core section were prepared to provide information on transport over a longer distance. Variations in U and/or Th content on the cm-scale between clays and carbonate-sandy layers are revealed by beta-scanning, which shows that the (dominant) clay is richer in both elements. Samples were digested using aqua regia followed by total HF dissolution, yielding two fractions. in all studied samples U was found to be concentrated in the HF digestion fraction. It has a high U/Th ratio and a study by SEM-EDS points to sub-mu m up to several mu m in size zircon grains as the main U-rich phase. This fraction consistently has U-234/U-238 activity ratios below unity. The minute zircon grains constitute the major reservoir of U in the rock and act as constant rate suppliers of U-234 into the rock matrix and the pore water. The aqua regia leach fraction was found to be enriched in Th, and complementary to the HF fraction, having U-234/U-238 activity ratios above unity. It is believed that these U activity ratios reflect the surplus of having U-234 delivered from the zircon grains. Some cm-spaced samples show bulk rock U-234/U-238 activity ratios that are markedly out of equilibrium. In most of them a striking negative correlation between the total U content and the bulk rock U-234/U-238 activity ratios is observed. This is interpreted to indicate net U-234 transfer from regions of higher supply of U-234 towards those of lower supply which is, in most cases, equivalent to transfer from clayey towards carbonate/sandy portions of the rock. In contrast, the 25 cm averaged samples all have uniform bulk rock U-234/U-238 activity ratios in equilibrium, indicating U immobility in the last 1-1.5 Ma on this spatial scale. It is concluded that the small-scale lithological variations which govern U spatial distribution in the Opalinus Clay are the major factor determining U-234 in situ supply rates, regulating its diffusive fluxes and controlling the observed bulk rock U-234/U-238 activity ratios. A simple box-model is presented to simulate the measured bulk rock U-234/U-238 activity ratios and to give an additional insight into the studied system. (C) 2008 Elsevier Ltd. All rights reserved.

Diffusion of HTO, Br-, I-, Cs+, Sr-85(2+) and Co-60(2+) in a clay formation: Results and modelling from an in situ experiment in Opalinus Clay

The migration of radioactive and chemical contaminants in clay materials and argillaceous host rocks is characterised by diffusion and retention processes. Valuable information on such processes can be gained by combining diffusion studies at laboratory scale with field migration tests. In this work, the outcome of a multi-tracer in situ migration test performed in the Opalinus Clay formation in the Mont Terri underground rock laboratory (Switzerland) is presented. Thus, 1.16 x 10(5) Bq/L of HTO, 3.96 x 10(3) Bq/L of Sr-85, 6.29 x 10(2) Bq/L of Co-60, 2.01 x 10(-3) mol/L Cs, 9.10 x 10(-4) mol/L I and 1.04 x 10(-3) mol/L Br were injected into the borehole. The decrease of the radioisotope concentrations in the borehole was monitored using in situ gamma-spectrometry. The other tracers were analyzed with state-of-the-art laboratory procedures after sampling of small water aliquots from the reservoir. The diffusion experiment was carried out over a period of one year after which the interval section was overcored and analyzed. Based on the experimental data from the tracer evolution in the borehole and the tracer profiles in the rock, the diffusion of tracers was modelled with the numerical code CRUNCH. The results obtained for HTO (H-3), I- and Br- confirm previous lab and in situ diffusion data. Anionic fluxes into the formation were smaller compared to HTO because of anion exclusion effects. The migration of the cations Sr-85(2+), Cs+ and Co-60(2+) was found to be governed by both diffusion and sorption processes. For Sr-85(2+), the slightly higher diffusivity relative to HTO and the low sorption value are consistent with laboratory diffusion measurements on small-scale samples. In the case of Cs+, the numerically deduced high diffusivity and the Freundlich-type sorption behaviour is also supported by ongoing laboratory data. For Co, no laboratory diffusion data were yet available for comparison; however, the modelled data suggests that Co-60(2+) sorption was weaker than would be expected from available batch sorption data. Overall, the results demonstrate the feasibility of the experimental setup for obtaining high-quality diffusion data for conservative and sorbing tracers. (C) 2007 Elsevier Ltd. All rights reserved.

Coupled W–Os–Pt isotope systematics in IVB iron meteorites: In situ neutron dosimetry for W isotope chronology

Tungsten isotope compositions of magmatic iron meteorites yield ages of differentiation that are within ±2 Ma of the formation of CAIs, with the exception of IVB irons that plot to systematically less radiogenic compositions yielding erroneously old ages. Secondary neutron capture due to galactic cosmic ray (GCR) irradiation is known to lower the ε182W of iron meteorites, adequate correction of which requires a measure of neutron dosage which has not been available, thus far. The W, Os and Pt isotope systematics of 12 of the 13 known IVB iron meteorites were determined by MC-ICP-MS (W, Os, Pt) and TIMS (Os). On the same dissolutions that yield precise ε182W, stable Os and Pt isotopes were determined as in situ neutron dosimeters for empirical correction of the ubiquitous cosmic-ray induced burn-out of 182W in iron meteorites. The W isotope data reveal a main cluster with ε182W of ∼−3.6, but a much larger range than observed in previous studies including irons (Weaver Mountains and Warburton Range) that show essentially no cosmogenic effect on their ε182W. The IVB data exhibits resolvable negative anomalies in ε189Os (−0.6ε) and complementary ε190Os anomalies (+0.4ε) in Tlacotepec due to neutron capture on 189Os which has approximately the same neutron capture cross section as 182W, and captures neutrons to produce 190Os. The least irradiated IVB iron, Warburton Range, has ε189Os and ε190Os identical to terrestrial values. Similarly, Pt isotopes, which are presented as ε192Pt, ε194Pt and ε196Pt range from +4.4ε to +53ε, +1.54ε to −0.32ε and +0.73ε to −0.20ε, respectively, also identify Tlacotepec and Dumont as the most GCR-damaged samples. In W–Os and W–Pt isotope space, the correlated isotope data back-project toward a 0-epsilon value of ε192Pt, ε189Os and ε190Os from which a pre-GCR irradiation ε182W of −3.42±0.09 (2σ) is derived. This pre-GCR irradiation ε182W is within uncertainty of the currently accepted CAI initial ε182W. The Pt and Os isotope correlations in the IVB irons are in good agreement with a nuclear model for spherical irons undergoing GCR spallation, although this model over-predicts the change of ε182W by ∼2×, indicating a need for better W neutron capture cross section determinations. A nucleosynthetic effect in ε184W in these irons of −0.14±0.08 is confirmed, consistent with the presence of Mo and Ru isotope anomalies in IVB irons. The lack of a non-GCR Os isotope anomaly in these irons requires more complex explanations for the production of W, Ru and Mo anomalies than nebular heterogeneity in the distribution of s-process to r-process nuclides.

Cosmogenic production rates and recoil loss effects in micrometeorites and interplanetary dust particles

We present a purely physical model to determine cosmogenic production rates for noble gases and radionuclides in micrometeorites (MMs) and interplanetary dust particles (IDPs) by solar cosmic-rays (SCR) and galactic cosmic-rays (GCR) fully considering recoil loss effects. Our model is based on various nuclear model codes to calculate recoil cross sections, recoil ranges, and finally the percentages of the cosmogenic nuclides that are lost as a function of grain size, chemical composition of the grain, and the spectral distribution of the projectiles. The main advantage of our new model compared with earlier approaches is that we consider the entire SCR particle spectrum up to 240 MeV and not only single energy points. Recoil losses for GCR-produced nuclides are assumed to be equal to recoil losses for SCR-produced nuclides. Combining the model predictions with Poynting-Robertson orbital lifetimes, we calculate cosmic-ray exposure ages for recently studied MMs, cosmic spherules, and IDPs. The ages for MMs and the cosmic-spherule are in the range <2.2–233 Ma, which corresponds, according to the Poynting-Robertson drag, to orbital distances in the range 4.0–34 AU. For two IDPs, we determine exposure ages of longer than 900 Ma, which corresponds to orbital distances larger than 150 AU. The orbital distance in the range 4–6 AU for one MM and the cosmic spherule indicate an origin either in the asteroid belt or release from comets coming either from the Kuiper Belt or the Oort Cloud. Three of the studied MMs have orbital distances in the range 23–34 AU, clearly indicating a cometary origin, either from short-period comets from the Kuiper Belt or from the Oort Cloud. The two IDPs have orbital distances of more than 150 AU, indicating an origin from Oort Cloud comets.

Chronostratigraphy of the 600,000 year old continental record of Lake Van

Lake Van sediment cores from the Ahlat Ridge and Northern Basin drill sites of the ICDP project PALEOVAN contain a wealth of information about past environmental processes. The sedimentary sequence was dated using climatostratigraphic alignment, varve chronology, tephrostratigraphy, argon-argon single-crystal dating, radiocarbon dating, magnetostratigraphy, and cosmogenic nuclides. Based on the lithostratigraphic framework, the different age constraints are compiled and a robust and precise chronology of the 600,000 year-old Lake Van record is constructed. Proxy records of total organic carbon content and sediment color, together with the calcium/potassium-ratios and arboreal pollen percentages of the 174-meter-long Ahlat Ridge record, mimic the Greenland isotope stratotype (NGRIP). Therefore, the proxy records are systematically aligned to the onsets of interstadials reflected in the NGRIP or synthesized Greenland ice-core stratigraphy. The chronology is constructed using 27 age control points derived from visual synchronization with the GICC05 timescale, an absolutely-dated speleothem record (e.g., Hulu, Sanbao, Linzhu cave) and the Epica Dome C timescale. In addition, the uppermost part of the sequence is complemented with four ages from Holocene varve chronology and two calibrated radiocarbon ages. Furthermore, nine argon-argon ages and a comparison of the relative paleointensity record of the magnetic field with reference curve PISO-1500 confirm the accuracy of the age model. Also the identification of the Laschamp event via measurements of 10Be in the sediment confirms the presented age model. The chronology of the Ahlat Ridge record is transferred to the 79-meter-long event-corrected composite record from the Northern Basin and supplemented by additional radiocarbon dating on organic marco-remains. The basal age of the Northern Basin record is estimated at ~90 ka. The variations of the time series of total organic carbon content, the Ca/K ratio, and the arboreal pollen percentages illustrate that the presented chronology and paleoclimate data are suited for reconstructions and modeling of the Quaternary and Pleistocene climate evolution in the Near East at millennial timescales. Furthermore, the chronology of the last 250 kyr can be used to test other dating techniques.

The neutron background of the XENON100 dark matter experiment

TheXENON100 experiment, installed underground at the LaboratoriNazionali del Gran Sasso, aims to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering off xenon nuclei. This paper presents a study on the nuclear recoil background of the experiment, taking into account neutron backgrounds from (alpha, n) reactions and spontaneous fission due to natural radioactivity in the detector and shield materials, as well as muon-induced neutrons. Based on MonteCarlo simulations and using measured radioactive contaminations of all detector components, we predict the nuclear recoil backgrounds for the WIMP search results published by theXENON100 experiment in 2011 and 2012, 0.11(-0.04)(+0.08) events and 0.17(-0.07)(+0.12) events, respectively, and conclude that they do not limit the sensitivity of the experiment.

Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms

Upon attack by leaf herbivores, many plants reallocate photoassimilates below ground. However, little is known about how plants respond when the roots themselves come under attack. We investigated induced resource allocation in maize plants that are infested by the larvae Western corn rootworm Diabrotica virgifera virgifera. Using radioactive 11CO2, we demonstrate that root-attacked maize plants allocate more new 11C carbon from source leaves to stems, but not to roots. Reduced meristematic activity and reduced invertase activity in attacked maize root systems are identified as possible drivers of this shoot reallocation response. The increased allocation of photoassimilates to stems is shown to be associated with a marked thickening of these tissues and increased growth of stem-borne crown roots. A strong quantitative correlation between stem thickness and root regrowth across different watering levels suggests that retaining photoassimilates in the shoots may help root-attacked plants to compensate for the loss of belowground tissues. Taken together, our results indicate that induced tolerance may be an important strategy of plants to withstand belowground attack. Furthermore, root herbivore-induced carbon reallocation needs to be taken into account when studying plant-mediated interactions between herbivores.

Assignment of the porcine tumour necrosis factor alpha and beta genes to the chromosome region 7p11-q11 by in situ hybridization

The loci of the porcine tumour necrosis factor genes, alpha (TNFA) and beta (TNFB), have been chromosomally assigned by radioactive in situ hybridization. The genomic probes for TNFA and TNFB yielded signals above 7p11-q11, a region that has been shown earlier to carry the porcine major histocompatibility locus (SLA). These mapping data along with preliminary molecular studies suggest a genomic organization of the SLA that is similar to that of human and murine major histocompatibility complexes.

Transport of iodide in structured clay–loam soil under maize during irrigation experiments analyzed using HYDRUS model

Transport of radioactive iodide 131I− in a structured clay loam soil under maize in a final growing phase was monitored during five consecutive irrigation experiments under ponding. Each time, 27 mm of water were applied. The water of the second experiment was spiked with 200 MBq of 131I− tracer. Its activity was monitored as functions of depth and time with Geiger-Müller (G-M) detectors in 11 vertically installed access tubes. The aim of the study was to widen our current knowledge of water and solute transport in unsaturated soil under different agriculturally cultivated settings. It was supposed that the change in 131I− activity (or counting rate) is proportional to the change in soil water content. Rapid increase followed by a gradual decrease in 131I− activity occurred at all depths and was attributed to preferential flow. The iodide transport through structured soil profile was simulated by the HYDRUS 1D model. The model predicted relatively deep percolation of iodide within a short time, in a good agreement with the observed vertical iodide distribution in soil. We found that the top 30 cm of the soil profile is the most vulnerable layer in terms of water and solute movement, which is the same depth where the root structure of maize can extend.

Folate Receptor Targeted Alpha-Therapy Using Terbium-149

Terbium-149 is among the most interesting therapeutic nuclides for medical applications. It decays by emission of short-range α-particles (Eα = 3.967 MeV) with a half-life of 4.12 h. The goal of this study was to investigate the anticancer efficacy of a 149Tb-labeled DOTA-folate conjugate (cm09) using folate receptor (FR)-positive cancer cells in vitro and in tumor-bearing mice. 149Tb was produced at the ISOLDE facility at CERN. Radiolabeling of cm09 with purified 149Tb resulted in a specific activity of ~1.2 MBq/nmol. In vitro assays performed with 149Tb-cm09 revealed a reduced KB cell viability in a FR-specific and activity concentration-dependent manner. Tumor-bearing mice were injected with saline only (group A) or with 149Tb-cm09 (group B: 2.2 MBq; group C: 3.0 MBq). A significant tumor growth delay was found in treated animals resulting in an increased average survival time of mice which received 149Tb-cm09 (B: 30.5 d; C: 43 d) compared to untreated controls (A: 21 d). Analysis of blood parameters revealed no signs of acute toxicity to the kidneys or liver in treated mice over the time of investigation. These results demonstrated the potential of folate-based α-radionuclide therapy in tumor-bearing mice.

Regional Radiation Pneumonitis After SIRT of a Subcapsular Liver Metastasis: What is the Effect of Direct Beta Irradiation?

We herein present a patient undergoing selective internal radiation therapy with an almost normal lung shunt fraction of 11.5 %, developing histologically proven radiation pneumonitis. Due to a predominance of pulmonary consolidations in the right lower lung and its proximity to a large liver metastases located in the dome of the right liver lobe a Monte Carlo simulation was performed to estimate the effect of direct irradiation of the lung parenchyma. According to our calculations direct irradiation seems negligible and RP is almost exclusively due to ectopic draining of radioactive spheres.

PLACENTAL URIC ACID TRANSPORTER GLUT9 IS MODULATED BY FREE IODINE

PLACENTAL URIC ACID TRANSPORTER GLUT9 IS MODULATED BY FREE IODINE Objectives: Materno-fetal transplacental transport is crucial for the fetal well-being. The altered expression of placental transport proteins under specific pathophysiological conditions may affect the intrauterine environment. Pre-eclampsia is often associated with high maternal uric acid serum levels. The regulation of the placental uric transport system and its transporter glucose transporter (GLUT)-9 are not fully understood yet. The aim of this study was to investigate the placental urate transport and to characterize its transporter GLUT9. Methods: In this study we used a transepithelial transport (Transwell®) model to assess uric acid transport activity. Electrophysiological techniques and radioactive ligand up-take assays were used to measure transport activity of GLUT9 expressed in Xenopus oocytes. Results: In the Transwell/model uric acid is transported across the BeWo choriocarcinoma cell monolayer with 530 pmol/min at the linear stage. We could successfully over-express GLUT9 using the Xenopus laevis oocytes expression system. Chloride modulates the urate transport system: interestingly replacing chloride with iodine resulted in a complete loss of urate transport activity.We determined the IC50 of iodine at 30uM concentration. In radioactive up-take experiments iodinehad noeffect on uric acid transport. Conclusions: In vitro the “materno-fetal” transport of uric acid is slow. This indicates that in vivo the child is protected from short-term fluctuations of maternal uric acid serum concentrations. The different results regarding iodine-mediated regulation of GLUT9 transport activity between electrophysiological and radioactive ligand uptake experiments may suggest that iodine does not directly inhibit uric acid transport, but changes the mode of up-take from an electrogenic to an electroneutral transport. GLUT9 is not an uric acid uniporter, there are more ions involved in the transport. This may allow regulating uric acid transport by the change from an active to a passive transport.