129I in rainwater across Argentina.

Concentrations of 127I and 129I in rainwater samples from several stations across Argentina (latitudes between 25° S and 55° S) were measured and analyzed for the assessment of distribution patterns and potential sources of 129I in the Southern Hemisphere. Measured 129I levels, clearly above those explainable by natural background and atmospheric nuclear weapons tests, can be understood by the injection into the Southern Hemisphere of 129I that had been discharged from nuclear fuel reprocessing plants in the Northern Hemisphere.

Application of 68Ga-PSMA-11 PET/CT in the Diagnosis of Prostate Cancer Clinical Relapse.

BACKGROUND: This work aims to present a nuclear medicine imaging service's data regarding applying positron emission-computing tomography (PET/CT) scans with the radiopharmaceutical 68Ga-PSMA-HBED-CC (68Ga-PSMA-11) to diagnose prostate cancer clinical relapse. METHODS: Eighty patients with a mean age of 68.26 years and an average prostatic-specific antigen blood level of 7.49 ng/ml (lower concentration = 0.17 ng/ml) received 68Ga-PSMA-11 intravenously, and full-body images of PET-CT scan were obtained. Of the total of patients admitted to the imaging service, 87.5% were examined for disease's biochemical recurrence and clinical relapse, and 70.0% had a previous radical prostatectomy (RP). RESULTS: Of the patients without RP, 95.8% were detected with intra-glandular disease. The 68Ga- PSMA-11 PET/CT imaging results revealed small lesions, even in patients with low blood levels of prostatic-specific antigen, mainly in metastatic cancer cases in lymph nodes and bones. CONCLUSION: The 68Ga-PSMA-11 PET/CT imaging was essential in detecting prostate cancer, with significantly high sensitivity in detecting recurrent cases. Due to its inherent reliability and sensitivity, PET/CT scanning with 68Ga-PSMA-11 received an increasing number of medical requests throughout the present follow-up study, confirming the augmented demand for this clinical imaging procedure in the regional medical community.

Radiolabeling of cidofovir with technetium-99m and biodistribution studies

Radiolabeling cidofovir with technetium-99m (99mTc-CDV) is an innovative procedure that enables real-time monitoring of the drug. Essays were performed in vitro, showing high radiolabel stability within 24 h. Blood clearance, biodistribution studies, and scintigraphic images were performed in healthy mice in order to evaluate the profile of the drug in vivo. 99mTc-CDV showed biphasic blood circulation time and significant kidney uptake, indicating that 99mTc-CDV is preferentially eliminated by the renal route. Bones also showed important uptake throughout the experiment. In summary, cidofovir was successfully labeled with technetium-99m and might be used in further studies to track the drug.

Evaluation of the Influence of the Conjugation Site of the Chelator Agent HYNIC to GLP1 Antagonist Radiotracer for Insulinoma Diagnosis.

BACKGROUND AND OBJECTIVE: Radiotracer diagnosis of insulinoma, can be done using somatostatin or glucagon-like peptide 1 (GLP-1). Performance of GLP-1 antagonists tends to be better than of agonists. METHODS: We investigated the uptake of the antagonist exendin (9-39), radiolabeled with technetium- 99m. Two different sites of the biomolecule were selected for chelator attachment. RESULTS: HYNIC-ßAla chelator attached to serine (C- terminus) of exendin, was associated with higher tumor uptake than to aspartate (N- terminus). CONCLUSION: The chelator position in the biomolecule influenced receptor uptake.

Mercury methylation and sulfate reduction rates in mangrove sediments, Rio de Janeiro, Brazil: The role of different microorganism consortia.

Recent studies have shown Hg methylation in mangrove sediments, however, little is known about the different microorganism consortia involved. We investigated the participation of prokaryotes in general, iron-reducing bacteria-IRB, sulfate-reducing bacteria-SRB, methanogens and fungi in Hg methylation and sulfate reduction rates (SRR) in mangrove sediments using iron amendments for IRB and specific inhibitors for the other microorganisms. Sediment samples were collected from two mangrove zones, tidal flat and mangrove forest (named root sediments). Samples were incubated with 203Hg or 35SO42- and Me203Hg/35Sulfur were measured by liquid scintillation. Methylmercury (MeHg) formation was significantly reduced when SRB (87.7%), prokaryotes (76%) and methanogens (36.5%) were inhibited in root sediments, but only SRB (51.6%) and prokaryotes (57.3%) in tidal flat. However, in the tidal flat, inhibition of methanogens doubled Hg methylation (104.5%). All inhibitors (except fungicide) significantly reduced SRR in both zones. In iron amended tidal flat samples, Hg methylation increased 56.5% at 100 µg g-1 and decreased at 500 and 1000 µg g-1 (57.8 and 82%). In the roots region, however, MeHg formation gradually decreased in response to Fe amendments from 100 µg g-1 (37.7%) to 1000 µg g-1 (93%). SRR decreased in all iron amendments. This first simultaneous evaluation of Hg methylation and sulfate-reduction and of the effect of iron and inhibitors on both processes suggest that SRB are important Hg methylators in mangrove sediments. However, it also suggests that SRB activity could not explain all MeHg formation. This implies the direct or indirect participation of other microorganisms such as IRB and methanogens and a complex relationship among these groups.

Electrokinetic removal of radionuclides contained in scintillation liquids absorbed in soil type Phaeozem.

Control samples of scintillation liquids - Phaeozem soil mixtures were prepared with different scintillation liquids as the support electrolyte, Install Gel® XF, (Ultima Gold AB™ and Ultima Gold XR™), to construct the polarization curves, and to select the cell potential with the highest mass transfer to remove 24Na (15 h) and 99mTc (6 h) as radiotracers from polluted Phaeozem soil. During the electrokinetic treatment (EKT), the removal of radionuclides contained in scintillation liquids absorbed in Phaeozem soil, liquid phase was characterized by Gas Chromatography coupled with a Flame Ionization Detector (GC-FID) and Fourier Transform Infrared Spectrometry (FTIR), solids by FTIR, before and after the application of cell potential. In this sense, the support electrolyte was selected based on the highest current generated (1 mA), as in the case of scintillation liquid 50% Ultima Gold XR™ + 50% Water (1:1), which was used for 6 h in the presence of a mesh and a titanium rod, as anode and cathode, respectively. Finally, the removal percentage accumulated in the liquid phase after the EKT of Phaeozem soil polluted by 99mTc was 61% close to the anode after 4 h. It was also 61% for 24Na close to cathode after 2 h, and after 4 h it was 71.8%.

Biodistribution studies of bee venom and spider toxin using radiotracers

The use of radiotracers allows the understanding of the bioavailability process, biodistribution, and kinetics of any molecule labelled with an isotope, which does not alter the molecule's biological properties. In this work, technetium-99m and iodine-125 were chosen as radiotracers for biodistribution studies in mice using bee (Apis mellifera) venom and a toxin (PnTX2-6) from the Brazilian "armed" spider (Phoneutria nigriventer) venom. Incorporated radioactivity was measured in the blood, brain, heart, lung, liver, kidney, adrenal gland, spleen, stomach, testicle, intestine, muscle, and thyroid gland. Results provided the blood kinetic parameter, and different organs distribution rates.(AU)

Biodistribution studies of bee venom and spider toxin using radiotracers

The use of radiotracers allows the understanding of the bioavailability process, biodistribution, and kinetics of any molecule labelled with an isotope, which does not alter the molecule's biological properties. In this work, technetium-99m and iodine-125 were chosen as radiotracers for biodistribution studies in mice using bee (Apis mellifera) venom and a toxin (PnTX2-6) from the Brazilian "armed" spider (Phoneutria nigriventer) venom. Incorporated radioactivity was measured in the blood, brain, heart, lung, liver, kidney, adrenal gland, spleen, stomach, testicle, intestine, muscle, and thyroid gland. Results provided the blood kinetic parameter, and different organs distribution rates.