Metallobiochemistry of ultratrace levels of bismuth in the rat II. Interaction of 205+206Bi3+ with tissue,intracellular and molecular components

BackgroundKnowledge on Bi metabolism in laboratory animals refers to studies at “extreme” exposures, i.e. pharmacologically relevant high-doses (mg kg⁻¹ b.w.) in relation to its medical use, or infinitesimal doses (pg kg⁻¹b.w.) concerning radiobiology protection and radiotherapeutic purposes. There are no specific studies on metabolic patterns of environmental exposure doses (ultratrace level, μg kg⁻¹ b.w.), becoming in this context Bi a “heavy metal fallen into oblivion”. We previously reported the results of the metabolic fate of ultratrace levels of Bi in the blood of rats [1]. In reference to the same study here we report the results of the retention and tissue binding of Bi with intracellular and molecular components.MethodsAnimals were intraperitoneally injected with 0.8 μg Bi kg⁻¹ b.w. as ^205+206Bi(NO)₃, alone or in combination with ⁵⁹Fe for the radiolabeling of iron proteins. The use of ^205+206Bi radiotracer allowed the determination of Bi down to pg fg⁻¹ in biological fluids, tissues, subcellular fractions, and biochemical components isolated by differential centrifugation, size exclusion chromatography, solvent extraction, precipitation, immunoprecipitation and dialysis.Main findingsAt 24 h post injection the kidney contained by far the highest Bi concentration (10 ng g⁻¹ wt.w.) followed by the thymus, spleen, liver, thyroid, trachea, femur, lung, adrenal gland, stomach, duodenum and pancreas (0.1 to 1.3 ng g⁻¹ wt.w.). Brain and testis showed smaller but consistently significant concentrations of the element (0.03 ng g⁻¹ wt.w). Urine was the predominant route of excretion. Intracellularly, liver, kidney, spleen, testis, and brain cytosols displayed the highest percentages (35%–58%) of Bi of homogenates. Liver and testis nuclei were the organelles with the highest Bi content (24 % and 27 %). However, when the recovered Bi of the liver was recorded as percent of total recovered Bi divided by percent of total recovered protein the lysosomes showed the highest relative specific activity than in other fractions. In the brain subcellular fractions Bi was incorporated by neuro-structures with the protein and not lipidic fraction of the myelin retaining 18 % of Bi of the total homogenate. After the liver intra-subcellular fractionation: (i) 65 % of the nuclear Bi was associated with the protein fraction of the nuclear membranes and 35 % with the bulk chromatin bound to non-histone and DNA fractions; (ii) about 50 % of the mitochondrial Bi was associated with inner and outer membranes being the other half recovered in the intramitochondrial matrix; (iii) in microsomes Bi showed a high affinity (close to 90 %) for the membranous components (rough and smooth membranes); (iv) In the liver cytosol three pools of Bi-binding proteins (molecular size > 300 kDa, 70 kDa and 10 kDa) were observed with ferritin and metallothionein–like protein identified as Bi-binding biomolecules. Three similar protein pools were also observed in the kidney cytosol. However, the amount of Bi, calculated in percent of the total cytosolic Bi, were significantly different compared to the corresponding pools of the liver cytosol.ConclusionsAt the best of our knowledge the present paper represents the first in vivo study, on the basis of an environmental toxicology approach, aiming at describing retention and binding of Bi in the rat at tissue, intracellular and molecular levels.     

Preliminary experience in sentinel node and occult lesion localization (SNOLL) technique—One center study

Aim

The aim of this study was to present one center experience in applying the SNOLL technique to patients with suspected occult breast lesions.

Background

In the last years, the widespread use of mammographic screening programs resulted in an increasing number of women with nonpalpable suspicious breast lesions requiring further examination. The new method called sentinel node and occult lesion localization (SNOLL) enables the intraoperative detection of nonpalpable breast tumors and sentinel node biopsy in one surgical procedure.

Materials and methods

46 patients with suspected malignant lesions or diagnosed non-palpable breast cancer were subjected to a pre-operative SNOLL procedure. The day before the surgery, they were administered two radiotracers: one to localize the tumor and the other to localize the sentinel node. During the surgery, the breast tumor and the sentinel node, which in most cases had been examined intraoperatively, were detected with a handheld gamma probe and resected under its control.

Results

All 46 (100%) patients had their occult breast lesions resected. Histopathologic examination revealed cancer in 40 patients: in situ in 2 cases, invasive in 38 cases. All these patients had their sentinel nodes examined. In one case only, the sentinel node could not be located with a gamma probe. Intraoperative tests showed the sentinel node to be metastatic in 5 patients, who were then given a simultaneous axillary lymphadenectomy. In addition, the final histopathologic examination revealed metastasis to the sentinel node in one patient, who had to be reoperated.

Conclusion

SNOLL is a modern technique that enables a precise intraoperative localization of non-palpable suspected malignant breast lesions in combination with a sentinel node biopsy. Extended application of intraoperative management leads to significant decrease in the number of reoperations performed in patients with early bread cancer.     

Is SNOLL a good localization technique in early breast cancer treatment? A single center’s experience

AimThe aim of this study was to evaluate the method and present one center’s experience in applying the SNOLL technique to patients with non-palpable suspicious breast lesions.Materials and methods371 patients with suspected malignant lesions or diagnosed non-palpable breast cancer were subjected to a preoperative SNOLL procedure. The day before the surgery, they were administered two radiotracers to localize the tumor in the breast and the sentinel node. The following day, with the help of a handheld gamma probe the breast conserving surgery was performed.ResultsAll 371 patients (100%) had their suspected occult breast lesions resected. Histo-pathological examination revealed cancer in 339 patients all these patients had their sentinel nodes examined. The intraoperative tests showed the sentinel node to be metastatic in 35 patients, who were then given a simultaneous axillary lymphadenectomy. Another 7 patients were diagnosed with positive lymph nodes in the final pathology and had to undergo a second operation. Reoperations compelled by positive surgical margins were performed in 26 cases.ConclusionsSNOLL as a good technique of intraoperative localization, enables to remove a nonpalpable breast cancer together with sentinel lymph node in a single surgical procedure. It seems to be a optional method to be used in patients treated with breast conserving therapy.     

Characteristics of Bremsstrahlung emissions of 177Lu, 188Re,and 90Y for SPECT/CT quantification in radionuclide therapy

PurposeBeta particles emitted by radioisotopes used in targeted radionuclide therapies (TRT) create Bremsstrahlung (BRS) which may affect SPECT quantification when imaging these isotopes. The purpose of the current study was to investigate the characteristics of Bremsstrahlung produced in tissue by three β-emitting radioisotopes used in TRT.MethodsMonte Carlo simulations of ¹⁷⁷Lu, ¹⁸⁸Re, and ⁹⁰Y sources placed in water filled cylinders were performed. BRS yields, mean energies and energy spectra for (a) all photons generated in the decays, (b) photons that were not absorbed and leave the cylinder, and (c) photons detected by the camera were analyzed. Next, the results of simulations were compared with those from experiments performed on a clinical SPECT camera using same acquisition conditions and phantom configurations as in simulations.ResultsSimulations reproduced relatively well the shapes of the measured spectra, except for ⁹⁰Y which showed an overestimation in the low energy range. Detailed analysis of the results allowed us to suggest best collimators and imaging conditions for each of the investigated isotopes. Finally, our simulations confirmed that the BRS contribution to the energy spectra in quantitative imaging of ¹⁷⁷Lu and ¹⁸⁸Re could be ignored.ConclusionsFor ¹⁷⁷Lu and ¹⁸⁸Re, BRS contributes only marginally to the total spectra recorded by the camera. Our analysis shows that MELP and HE collimators are the best for imaging these two isotopes. For ⁹⁰Y, HE collimator should be used.     

Metallobiochemistry of ultratrace levels of bismuth in the rat I. Metabolic patterns of 205+206Bi3+ in the blood

BackgroundThe number of the applications of bismuth (Bi) is rapidly and remarkably increasing, enhancing the chance to increase the levels to which humans are normally daily exposed. The interest to Bi comes also from the potential of Bi-based nanoparticles (BiNPs) for industrial and biomedical purposes. Like other metal-based NPs used in nanomedicine, BiNPs may release ultratrace amounts of Bi ions when injected. The metabolic fate and toxicity of these ions still needs to be evaluated. At present, knowledge of Bi metabolism in laboratory animals refers almost solely to studies under unnatural “extreme” exposures, i.e. pharmacologically relevant high-doses (up to thousand mg kg⁻¹) in relation to its medical use, or infinitesimal-doses (pg kg⁻¹ as non-carrier-added Bi radioisotopes) for radiobiology protection, diagnostic and radiotherapeutic purposes. No specific study exists on the “metabolic patterns” in animal models exposed to levels of Bi, i.e. at “environmental dose exposure” that reflect the human daily exposure (μg kg⁻¹).MethodologyRats were intraperitoneally injected with 0.8 μg Bi kg⁻¹ bw as ^205+206Bi(NO)₃ alone or in combination with ⁵⁹Fe for radiolabelling of iron proteins. The use of ^205+206Bi radiotracers allowed the detection and measurement down to pg fg⁻¹ of the element in the blood biochemical compartments and protein fractions as isolated by differential centrifugation, size exclusion- and ion exchange chromatography, electrophoresis, solvent extraction, precipitation and dialysis.Results24 h after the administration, the blood concentration of Bi was 0.18 ng mL⁻¹, with a repartition plasma/red blod cells (RBC) in a ratio of 2:1. Elution profiles of plasma from gel filtration on Sephadex G-150 showed four pools of Bi-binder proteins with different molecular sizes (> 300 kDa, 160 kDa, 70 kDa and < 6.5 kDa). In the 70 kDa fraction transferrin and albumin were identified as biomolecule carriers for Bi. In red blood cells, Bi was distributed between cytosol and membranes (ghosts) in a ratio of about 5:1. In the cytosol, low molecular components (LMWC) and the hemoglobin associated the Bi in a ratio of about 1.8:1. In the hemoglobin molecule, Bi was bound to the beta polypeptide chain of the globin. In the ghosts, Bi was detected at more than one site of the protein fraction, with no binding with lipids. Dialysis experiments and the consistently high recovery (80–90 %) of ²⁰⁶Bi from chromatography of ²⁰⁶Bi-containing biocomponents suggest that Bi was firmly complexed at physiological pH with a low degree of breaking during the applications of experimental protocols for the isolation of the ²⁰⁶Bi-biocomplexes. These latter were sensitive to acid buffer pH 5, and to the presence of complexing agents in the dialysis fluid.ConclusionsOn the basis of an environmental biochemical toxicology approach, we have undertaken a study on the metabolic patterns of Bi³⁺ ions in rats at tissue, subcellular and molecular level with the identification of cellular Bi-binding components. As a first part of the study the present work reports the results concerned with the metabolic fate of ultratrace levels of ^205+206Bi(NO)₃ in the blood.     

Protein metabolism. 3. Relationship between albumin metabolism and elevated liver protein synthesis in the guinea pig infected with Trichostrongylus colubriformis

Studies of the incorporation of ¹⁴C-l-leucine into polypeptides by isolated liver ribosomes from guinea pigs confirmed previous in vivo studies that showed that Trichostrongylus colubriformis infection results in an elevated hepatic protein synthesis.The increased rate of protein synthesis was associated with the membrane-bound ribosomes that synthesize the circulating plasma proteins. Inappetance of infected animals was not resposible for the increased rate of synthesis by the membrane-bound ribosomes, but it was found that undernourishment may stimulate synthesis by free ribosomes.Plasma albumin turnover rate and loss into the intestine were both significantly increased in infected guinea pigs. It was concluded that these changes stimulated protein synthesis by membrane-bound ribosomes.The importance of elevated liver protein synthesis and loss of plasma protein in gastrointestinal nematode infections is discussed.     

Decontamination of radioisotopes

Contaminations with radioactive material may occur in several situations related to medicine, industry or research. Seriousness of the incident depends mainly on the radioactive element involved; usually there are no major acute health effects, but in the long term can cause malignancies, leukemia, genetic defects and teratogenic anomalies.The most common is superficial contamination, but the radioactive material can get into the body and be retained by the cells of target organs, injuring directly and permanently sensitive elements of the body. Rapid intervention is very important to remove the radioactive material without spreading it. Work must be performed in a specially prepared area and personnel involved should wear special protective clothing. For external decontamination general cleaning techniques are used, usually do not require chemical techniques. For internal decontamination is necessary to use specific agents, according to the causative element, as well physiological interventions to enhance elimination and excretion.