Antitumor Activity of Axitinib in Lung Carcinoids: A Preclinical Study

Lung carcinoids (LCs) comprise well-differentiated neuroendocrine tumors classified as typical (TCs) and atypical (ACs) carcinoids. Unfortunately, curative therapies remain elusive for metastatic LCs, which account for 25-30% of cases. This study evaluated the antitumor activity of axitinib (AXI), a second-generation tyrosine kinase inhibitor selectively targeting vascular endothelial growth factor receptors (VEGFR-1, VEGFR-2, VEGFR-3) in human lung TC (NCI-H727, UMC-11, NCI-H835) and AC (NCI-H720) cell lines. In vitro and in vivo (zebrafish) assays were performed following AXI treatment to gather several read-outs about cell viability, cell cycle, the secretion of proangiogenic factors, apoptosis, tumor-induced angiogenesis and migration. AXI demonstrated relevant antitumor activity in human LC cells, with pronounced effects observed in UMC-11 and NCI-H720, characterized by cell cycle perturbation and apoptosis induction. AXI significantly hindered tumor induced-angiogenesis in Tg(fli1a:EGFP)y1 zebrafish embryos implanted with all LC cell lines and also reduced the invasiveness of NCI-H720 cells, as well as the secretion of several proangiogenic factors. In conclusion, our study provides initial evidence supporting the potential anti-tumor activity of AXI in LC, offering a promising basis for future investigations in mammalian animal models and, eventually, progressing to clinical trials.

Animal Feasibility Study of a Novel Spinal Cord Stimulation Multicolumn Lead (Heron Lead)

BACKGROUND

Currently available spinal cord stimulation paddle leads require a laminectomy, limiting the types of clinicians who can implant and increasing the risk of complications. Recently, WISE S.r.l. designed a prototype multicolumn lead named the Heron® lead that can be implanted percutaneously. The purpose of the study was to examine the efficiency of placing a paddle lead percutaneously.

METHODS

Ten sheep were assigned to either the Heron lead group (n = 7) or the control group (n = 3). The sheep were observed for 13 weeks after implantation. Neurological and clinical examinations were conducted prior to surgery and then during the follow-up period. The implantation sites were evaluated through macroscopic observations during the article explantation and the lead migration was evaluated by comparing the article positioning at the surgery, four weeks after the surgery and at the explantation day through fluoroscope images. A qualitative comparison was made between the results collected with the test article and the control article.

RESULTS

Observations at the surgical sites indicate that test animals appeared to have less swelling around the surgical wound than control ones in the first 14 days, but no impact on wound healing was noticed. Additionally, no clear difference was observed in pain scores between the two groups, with observations tending to show that the maximum pain was occurring later in the test group with respect to the control group. General clinical observations showed no major difference between the two groups, and determined clinical abnormalities were not directly related to the procedure. Lastly, neurological deficits frequency decreased from the first to last animal operated, regardless of their test or control status.

CONCLUSIONS

Our study concluded that the Heron lead is safe to implant, with a safety profile similar to the control article. Additionally, we conclude that the Heron lead is effective in reducing lead migration events.

Neuroendocrine Tumors: A Comprehensive Review on Nutritional Approaches

Neuroendocrine neoplasms are a heterogeneous group of neoplasms with increasing incidence, high prevalence, and survival worldwide. About 90% of cases are well differentiated forms, the so-called neuroendocrine tumors (NETs), with slow proliferation rates and prolonged survival but frequent development of liver metastases and endocrine syndromes. Both the tumor itself and systemic therapy may have an impact on patient nutrition. Malnutrition has a negative impact on outcome in patients with NETs, as well as obesity. In addition, obesity and metabolic syndrome have been shown to be risk factors for both the development and prognosis of NET. Therefore, dietary assessment based on body composition and lifestyle modifications should be an integral part of the treatment of NET patients. Nutrition plans, properly formulated by a dietician, are an integral part of the multidisciplinary treatment team for patients with NETs because they allow an improvement in quality of life, providing a tailored approach based on nutritional needs and nutritional manageable signs and/or symptoms related to pharmacological treatment. The aim of this review is to condense the latest evidence on the role of the most used dietary models, the Mediterranean diet, the ketogenic diet, and intermittent fasting, in the context of NETs, while considering the clinical and molecular mechanisms by which these dietary models act.

Long-term effects of somatostatin analogues in rat GH-secreting pituitary tumor cell lines

PURPOSE

First-generation somatostatin analogs, octreotide (OCT) and lanreotide, are the cornerstone for the medical treatment of growth hormone (GH)-secreting pituitary tumors. A new multireceptor analog, such as pasireotide (PAS), showed better activity than OCT in long-term treatment of patients with acromegaly, but modulation of intracellular key processes is still unclear in vitro. In this study, we evaluated the antitumor activity of OCT and PAS in two GH-secreting pituitary tumor cell lines, GH3 and GH4C1, after a long-term incubation.

METHODS

The effects of PAS and OCT on the cell viability, cell cycle, apoptosis, GH secretion, and tumor-induced angiogenesis have been evaluated through a colorimetric method (MTS Assay), DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, ELISA assay and zebrafish platform, respectively.

RESULTS

PAS showed a more potent antitumor activity compared to OCT in GH3 cell line exerted through inhibition of cell viability, perturbation of cell cycle progression, and induction of apoptosis after 6 days of incubation. A concomitant decrease in GH secretion has been observed after 2 days of incubation only with PAS. No effect on tumor-induced angiogenesis has been reported after treatment with OCT or PAS in zebrafish/tumor xenograft model.

CONCLUSION

Long-term incubation with PAS showed a more potent antitumor activity than that reported after OCT in GH3 cells, mainly modulated by a cell cycle perturbation and a relevant induction in apoptosis.

Role of Epigenetic Therapy in the Modulation of Tumor Growth and Migration in Human Castration-Resistant Prostate Cancer Cells with Neuroendocrine Differentiation

INTRODUCTION

Neuroendocrine transdifferentiation (NED) of prostate cancer (PC) cells is associated with the development of resistance to antiandrogen therapy and poor prognosis in patients with castration-resistant PC (CRPC). Many of the molecular events, involved in NED, appear to be mediated by epigenetic mechanisms. In this study, we evaluated the antitumor activity and epigenetic modulation of 2 epigenetic drugs, such as the demethylating agent 5-aza-2'-deoxycytidine (AZA) and the methyl donor S-adenosylmethionine (SAM), in 2 human CRPC cell lines with NED (DU-145 and PC-3).

METHODS

The effects of AZA and SAM on cell viability, cell cycle, apoptosis, migration, and genome-wide DNA methylation profiling have been evaluated.

RESULTS

Both drugs showed a prominent antitumor activity in DU-145 and PC-3 cells, through perturbation of cell cycle progression, induction of apoptosis, and inhibition of cell migration. AZA and SAM reversed NED in DU-145 and PC-3, respectively. Moreover, AZA treatment modified DNA methylation pattern in DU-145 cells, sustaining a pervasive hypomethylation of the genome, with a relevant effect on several pathways involved in the regulation of cell proliferation, apoptosis, and cell migration, in particular Wnt/β-catenin.

CONCLUSIONS

A relevant antitumor activity of these epigenetic drugs on CRPC cell lines with NED opens a new scenario in the therapy of this lethal variant of PC.

Efficacy of a Novel Second-Generation Somatostatin-Dopamine Chimera (TBR-065) in Human Medullary Thyroid Cancer: A Preclinical Study

INTRODUCTION

Somatostatin and dopamine (DA) receptors have a pivotal role in controlling hormone secretion and cell proliferation in different neuroendocrine neoplasms, including medullary thyroid cancer (MTC). In the present preclinical study, we evaluated the anti-tumor activity of TBR-065 (formerly BIM-23B065), a second-generation somatostatin-DA chimera, in 2 human MTC cell lines.

METHODS

The effects of lanreotide (LAN) and TBR-065 on cell growth and proliferation, calcitonin (CT) secretion, cell cycle, apoptosis, cell migration, and tumor-induced angiogenesis have been evaluated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, DNA flow cytometry with propidium iodide (PI), Annexin V-FITC/PI staining, electrochemiluminescence immuno assay, wound-healing assay, and zebrafish platform, respectively.

RESULTS

TBR-065 exerted a more prominent anti-tumor activity than LAN in both MTC cell lines, as shown by inhibition of cell proliferation (maximal inhibition in TT: -50.3 and -37.6%, respectively; in MZ-CRC-1: -58.8 and -27%, respectively) and migration (in TT: -42.7 and -22.9%, respectively; in MZ-CRC-1: -75.5 and -58.2%, respectively). Only the new chimera decreased significantly the fraction of cells in S phase (TT: -33.8%; MZ-CRC-1: -18.8%) and increased cells in G2/M phase (TT: +13%; MZ-CRC-1: +30.5%). In addition, TBR-065 exerted a more prominent pro-apoptotic effect than LAN in TT cells. A concomitant decrease in CT secretion was observed after 2 days of incubation with both drugs, with a more relevant effect of TBR-065. However, neither LAN nor TBR-065 showed any effect on tumor-induced angiogenesis, as evaluated using a zebrafish/tumor xenograft model.

DISCUSSION/CONCLUSION

In MTC cell lines, a second-generation somatostatin-DA analog, TBR-065, exerts a more relevant anti-tumor activity than LAN, through modulation of cell cycle, induction of apoptosis, and reduction in migration. Further studies are required to establish whether TBR-065 has comparable potent inhibitory effects on tumor growth in vivo.

Ethical aspects in the use of radiation in medicine: update from ICRP Task Group 109

Whereas scientific evidence is the basis for recommendations and guidance on radiological protection, professional ethics is critically important and should always guide professional behaviour. The International Commission on Radiological Protection (ICRP) established Task Group 109 to advise medical professionals, patients, families, carers, the public, and authorities about the ethical aspects of radiological protection of patients in the diagnostic and therapeutic use of radiation in medicine. Occupational exposures and research-related exposures are not within the scope of this task group. Task Group 109 will produce a report that will be available to the different interested parties for consultation before publication. Presently, the report is at the stage of a working document that has benefitted from an international workshop organised on the topic by the World Health Organization. It presents the history of ethics in medicine in ICRP, and explains why this subject is important, and the benefits it can bring to the standard biomedical ethics. As risk is an essential part in decision-making and communication, a summary is included on what is known about the dose-effect relationship, with emphasis on the associated uncertainties. Once this theoretical framework has been presented, the report becomes resolutely more practical. First, it proposes an evaluation method to analyse specific situations from an ethical point of view. This method allows stakeholders to review a set of six ethical values and provides hints on how they could be balanced. Next, various situations (e.g. pregnancy, elderly, paediatric, end of life) are considered in two steps: first within a realistic, ethically challenging scenario on which the evaluation method is applied; and second within a more general context. Scenarios are presented and discussed with attention to specific patient circumstances, and on how and which reflections on ethical values can be of help in the decision-making process. Finally, two important related aspects are considered: how should we communicate with patients, family, and other stakeholders; and how should we incorporate ethics into the education and training of medical professionals?

Fishing for neuroendocrine tumors

Neuroendocrine tumors (NETs) are a class of rare and heterogeneous neoplasms that originate from the neuroendocrine system. In several cases, these neoplasms can release bioactive hormones leading to characteristic clinical syndromes and hormonal dysregulations with detrimental impact on the quality of life and survival of these patients. Only few animal models are currently available to investigate pathogenesis, progression and functional syndromes in NETs and to identify new therapeutic strategies. The tropical teleost zebrafish (Danio rerio) is a popular vertebrate model system that offers unique advantages for the study of several biological processes, ranging from embryonic development to human diseases such as cancer. In this review, we summarize recent advances on zebrafish models for NET preclinical research that take advantage of modern genetic and transplantable technologies. In the future, these tools may have a role in the treatment decision-making and tertiary prevention of NETs.

Antitumor activity of interferon-β1a in hormone refractory prostate cancer with neuroendocrine differentiation

PURPOSE

Type I interferons (IFN-α and IFN-β) are a class of cytokines that exert several biological activities, such as modulation of cell proliferation and differentiation and of the immune system. Although these cytokines interact with a common receptor complex, IFN-β showed a more potent antitumor activity than IFN-α in several tumor models. New recombinant human IFN-β products, such as IFN-β1a and IFN-β1b, have been produced in order to improve the stability and bioavailability of natural IFN-β. In this report, we analyzed the effects of recombinant IFN-β1a on the cell proliferation of two human androgen-resistant prostate cancer cell lines with neuroendocrine differentiation (DU-145, PC-3) and related mechanisms of action.

METHODS

The effects of IFN-β1a on the cell growth proliferation, cell cycle, and apoptosis have been evaluated in DU-145 and PC-3 cells through MTT assay, DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, respectively. Moreover, the expression of neuron-specific enolase (NSE), cleaved caspase-3, caspase-8, and PARP was evaluated through Western blotting.

RESULTS

IFN-β1a showed a significant anti-proliferative activity in both androgen-resistant cell lines. This effect was related to cell cycle perturbation and induction in apoptosis, as shown by flow cytometric analysis, the activation of caspase-3 and caspase-8 and PARP cleavage during incubation with IFN-β1a. Moreover, this cytokine reduced the expression of NSE in both cell lines.

CONCLUSIONS

Recombinant IFN-β1a (Rebif) showed a potent in vitro anti-proliferative activity in androgen-resistant prostate cancer cells, and it could represent a promising tool for the treatment of this tumor.

A Review of Healthcare Failure Mode and Effects Analysis (HFMEA) in Radiotherapy

This paper presents a review of risk analyses in radiotherapy (RT) processes carried out by using Healthcare Failure Mode Effect Analysis (HFMEA) methodology, a qualitative method that proactively identifies risks to patients and corrects medical errors before they occur. This literature review was performed to provide an overview of how to approach the development of HFMEA applications in modern RT procedures, comparing recently published research conducted to support proactive programs to identify risks. On the basis of the reviewed literature, the paper suggests HFMEA shortcomings that need to be addressed.

Implications of the implementation of the revised dose limit to the lens of the eye: the view of IRPA professionals

In April 2011, the International Commission on Radiological Protection issued a statement on reduction of the equivalent dose limits for the lens of the eye, and strongly recommended its consideration in the revision of the International Atomic Energy Agency's International Basic Safety Standards on Radiation Protection. The reduced dose limit was incorporated in the final version of the Basic Safety Standards. As significant concern was expressed by radiation protection professionals worldwide, the International Radiation Protection Association (IRPA) established a task group to assess the impact of implementation of the revised dose limit for the lens of the eye for occupational exposure. IRPA Associate Societies (ASs) were asked for their views using a questionnaire addressing three topics: implications for dosimetry, implications for methods of protection, and wider implications. The responses received indicate various methods of approach and express different points of view, reflecting nuances of particular ASs or specific professional groups. Topic experts nominated by ASs were selected to assist with collation of responses, and a report was produced by the task group. Conclusions were drawn on the three issues, including potential cost implications. A number of recommendations were drawn from the responses received including: the request for more understanding about the relationship between exposure of the lens of the eye and cataract formation, and further guidance to assist implementation; the importance of economic and social considerations when introducing the limits into national regulations; the need to propose or define procedures related to employment of people with existing or pre-cataract conditions; and the practical aspects relating to dosimetry and protective equipment.

Implications in dosimetry of the implementation of the revised dose limit to the lens of the eye

In 2012, International Radiation Protection Association (IRPA) established a Task Group to provide an assessment of the impact of the implementation of the ICRP-revised dose limit for the lens of the eye for occupational exposure. Associated Societies (ASs) of IRPA were asked to provide views and comments on the basis of a questionnaire addressing three principal topics: (i) implications for dosimetry, (ii) implications for methods of protection and (iii) wider implications of implementing the revised limits. A summary of the collated responses regarding dosimetry is presented and discussed. There is large agreement on the most critical aspects and difficulties in setting up an appropriate monitoring programme for the lens of the eyes. The recent international standards and technical documents provide guidance for some of the concerns but other challenges remain in terms of awareness, acceptance and practicalities.

Units related to radiation exposure and radioactivity in mass media: the Fukushima case study in Europe and Russia

Using an analysis of the way European newspapers covered the Fukushima nuclear accident, this article explores how the mass media transmit information about radiation risks from experts to the general public. The study applied a media content analysis method on a total of 1340 articles from 12 leading newspapers in 6 countries: Belgium (N = 260), Italy (N = 270), Norway (N = 133), Russia (N = 172), Slovenia (N = 190) and Spain (N = 315). All articles analysed were selected as being directly or indirectly related to the Fukushima accident by containing the word 'nuclear' and/or 'Fukushima' and were published between the 11th March and the 11th May 2011. The data presented here focus specifically on a cross-cultural comparison of the way the media use quantitative units. Results suggest that although experts are accustomed to communicating about radiological risks in technical language, often using quantitative units to describe the risks, mass media do not tend to use these units in their reporting. Although the study found a large variation in the measurement units used in different countries, it appeared that journalists in all the analysed countries preferred to describe radioactivity by comparing different radiation exposures, rather than reporting the actual measured units. The paper concludes with some practical guidelines for sound public communication about radiation risks.

Report of Task Group on the implications of the implementation of the ICRP recommendations for a revised dose limit to the lens of the eye

This report was commissioned by the IRPA President to provide an assessment of the impact on members of IRPA Associate Societies of the introduction of ICRP recommendations for a reduced dose limit for the lens of the eye. The report summarises current practice and considers possible changes that may be required. Recommendations for further collaboration, clarification and changes to working practices are suggested.

Minimising activity and dose with enhanced image quality by radiopharmaceutical administrations

Owing to the introduction of new diagnostic procedures, such as computed tomography (CT), positron emission tomography (PET) and single photon emission computed tomography (SPECT), the individual dose caused by medical exposures has grown rapidly in the last years. This is especially a subject to radiation protection for nuclear medical diagnosis, since in this case radiopharmaceuticals are administered to the patient, meaning not only a radiation exposure to the diseased tissue but also to the healthy tissues of large parts of the body. 'Minimizing Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations' (MADEIRA) is a project cofunded by the European Commission within the Seventh Euratom Framework Programme that aims to improve three-dimensional (3D) nuclear medical imaging technologies significantly. MADEIRA is aiming to improve the efficacy and safety of 3D PET and SPECT functional imaging by optimising the spatial resolution and the signal-to-noise ratio, improving the knowledge of the temporal variation of the radiopharmaceuticals' uptake in and clearance from tumourous and healthy tissues, and evaluation of the corresponding patient dose. Using an optimised imaging procedure that improves the information gained per unit administered dose, MADEIRA aims especially to reduce the dose to healthy tissues of the patient. In this paper, an overall summary of the current achievements will be presented.

Measurement techniques for tracer kinetic studies with stable isotopes of zirconium

Biokinetic models are used in radiation protection to assess internal radiation doses. Experiments with stable isotopes as tracers can be performed to obtain characteristic parameters of these models. Two methods for the measurement of zirconium isotopes in human biological samples are presented--thermal ionisation mass spectrometry (TIMS) and proton nuclear activation analysis (PNA). Descriptions include sample preparation, operating conditions, relative uncertainties and method detection limits as well as important properties of both methods.

Coordination of research on internal dosimetry in Europe: the CONRAD project

The EUropean RAdiation DOSimetry Group (EURADOS) initiated in 2005 the CONRAD Project, a Coordinated Network for Radiation Dosimetry funded by the European Commission (EC), within the 6th Framework Programme (FP). The main purpose of CONRAD is to generate a European Network in the field of Radiation Dosimetry and to promote both research activities and dissemination of knowledge. The objective of CONRAD Work Package 5 (WP5) is the coordination of research on assessment and evaluation of internal exposures. Nineteen institutes from 14 countries participate in this action. Some of the activities to be developed are continuations of former European projects supported by the EC in the 5th FP (OMINEX and IDEAS). Other tasks are linked with ICRP activities, and there are new actions never considered before. A collaboration is established with CONRAD Work Package 4, dealing with Computational Dosimetry, to organise an intercomparison on Monte Carlo modelling for in vivo measurements of (241)Am deposited in a knee phantom. Preliminary results associated with CONRAD WP5 tasks are presented here.

The work of the CONRAD task group 5.2: research studies on biokinetic models

The objective of this Task Group is the coordination of research studies on biokinetic models and the evaluation of the implications of new biokinetic models on dose assessment and safety standards. For this the new ICRP models, which will be used for a revision of ICRP Publications 30, 54, 68 and 78, are implemented into six different computer codes in five European countries and quality assured by intercomparison procedures. The work has started with the implementation of the new ICRP Alimentary Tract Model. New systemic models and the new NCRP wound model will follow. The work also includes the evaluation of experimental results in terms of formulation by the new model structures and a quality assurance of model formulation.

The use of alpha-Al2O3:C in Risø OSL single grains attachment system for assessing the spatial dose rate distribution due to incorporation of 90Sr in human teeth

The possibility of using a single grain OSL attachment system developed by the Risø National Laboratory (Roskilde, Denmark) for assessing the spatial distribution of radionuclides incorporated in human tissues was investigated. Detectors containing arrays of single grains of alpha-Al2O3)C powder (Landauer Inc., USA) were prepared using aluminium discs (diameter 9.7 mm), which can accommodate 100 single grains in 0.3 mm holes positioned in a 10 x 10 grid. The luminescence and dosimetric properties of each grain were investigated by exposing the detectors to uniform photon radiation fields. After the characterisation of the detectors, the systems were tested to assess the spatial dose rate distribution because of 90Sr incorporated in a tooth sample extracted from an inhabitant of the Techa River region.

Determination of dose rates from natural radionuclides in dental materials

Different types of materials used for dental prosthetics restoration, including feldspathic ceramics, glass ceramics, zirconia-based ceramics, alumina-based ceramics, and resin-based materials, were investigated with regard to content of natural radionuclides by means of thermoluminescence beta dosimetry and gamma spectrometry. The gross beta dose rate from feldspathic and glass ceramics was about ten times higher than the background measurement, whereas resin-based materials generated negligible beta dose rate, similarly to natural tooth samples. The specific activity of uranium and thorium was significantly below the levels found in the period when addition of uranium to dental porcelain materials was still permitted. The high-beta dose levels observed in feldspathic porcelains and glass ceramics are thus mainly ascribable to (40)K, naturally present in these specimens. Although the measured values are below the recommended limits, results indicate that patients with prostheses are subject to higher dose levels than other members of the population. Alumina- and zirconia-based ceramics might be a promising alternative, as they have generally lower beta dose rates than the conventional porcelain materials. However, the dosimetry results, which imply the presence of inhomogeneously distributed clusters of radionuclides in the sample matrix, and the still unsuitable structural properties call for further optimization of these materials.

Influence of the chemical form on the plasma clearance of ruthenium in humans

The radioisotopes of ruthenium (103Ru and 106Ru) are abundant fission products and represent a radiological risk for the population in case of nuclear accidents. Few biokinetic studies have been performed on humans up to now and consequently the current model recommended by ICRP for ruthenium is derived mainly by extrapolation from animal data. The stable isotope 101Ru and proton activation analysis have been used to study the biokinetics of Ru in blood plasma samples taken during 8 studies in three healthy volunteers. The results obtained demonstrated that complexed Ru (in the form of citrate Ru(IV) complexes) is cleared from blood plasma very rapidly (characteristic half time of 17+/-2 min), while inorganic Ru remains longer in the systemic circulation, and is transferred to other organs and/or excreted with a biological half time of 23+/-2h. Good reproducibility of the clearance curves indicated no evidence of inter- or intra-individual variability when the same Ru solution was injected in repeated experiments to different subjects.

A re-evaluation of the biokinetics of zirconium in humans

There is much interest in understanding the biokinetics of zirconium in humans due to the potential radiological risk represented by the radionuclide 95Zr and by its daughter 95Nb. Despite the significance of zirconium, few data are available on the actual biokinetics of zirconium in humans. Accordingly the biokinetic model currently recommended by ICRP for this element is based mainly on data from animal experiments. In this study, the use of the stable isotopes 90Zr and 96Zr as tracers has enabled the conduct of 6 biokinetic investigations in 3 healthy volunteers. These studies have provided new valuable information about intestinal absorption and kinetics in blood plasma of zirconium and have been used for the set-up of a more realistic compartmental model with possible applications for dosimetric purposes.

Stable tracer investigations in humans for assessing the biokinetics of ruthenium and zirconium radionuclides

The interest in the biokinetics of ruthenium and zirconium in humans is justified by the potential radiological risk represented by their radionuclides. Only a few data related to the biokinetics of ruthenium and zirconium in humans are available and, accordingly, the biokinetic models currently recommended by the ICRP for these elements are mainly based on data from animal experiments. The use of stable isotopes as tracers, coupled with a proper analytical technique (nuclear activation analysis with protons) for their determination in biological samples, represents an ethically acceptable methodology for biokinetic investigations, being free from any radiation risk for the volunteer subjects. In this work, the results obtained in eight biokinetic investigations for ruthenium, conducted on a total of three healthy volunteers, and six for zirconium, performed on a total of three subjects, are presented and compared to the predictions of the ICRP models.

Regional dependence of urinary uranium baseline levels in non-exposed subjects with particular reference to volunteers from Northern Italy

Knowledge of the level of natural uranium (U) in the human body is fundamental in order to estimate the potentially hazardous incorporation in accidentally exposed subjects. A constant monitoring of exposed workers needs reliable reference baseline values, which can be determined by measuring the U concentration in urine. ICPMS has proven to be a fast, reliable and highly sensitive technique for this purpose. Non-uniformity in the distribution of U levels in various regions and differences in dietary habits account for the significant regional variations of U concentration in urine in non-exposed subjects. In this paper, the determination of daily uranium urinary excretion levels in a group of 12 non-exposed subjects from Northern Italy is presented and compared to data present in the published literature and to values obtained in a larger group of German volunteers. The urinary U output values observed in the Italian subset are generally higher than the corresponding levels measured in other groups. This could be the result of a higher intake of U from liquids, as assessed by the determination of U concentration in drinking waters.

Sensitivity analysis techniques applied to a revised model of molybdenum biokinetics

A revised model of molybdenum biokinetics in humans was recently developed on the basis of experimental data gathered in specific investigations conducted with stable tracers. The model can be used for radiation protection purposes, and it is also a suitable working tool for designing new investigations aimed at further improvements to the model. For the latter goal, a sensitivity analysis was performed in order to determine the most significant model parameters in relation to output measurements performed in studies of molybdenum metabolism. A typical sensitivity analysis approach was adopted, considering the effects in variation of model parameters on the time courses of model outputs such as urinary excretion and blood clearance. A recent new sensitivity technique was considered too, based on the calculation of the so-called generalised sensitivity functions. This combines the sensitivities of the model output with respect to model parameters (as in the typical sensitivity analysis method), with the sensitivities of parameter estimates with respect to changes in model outputs. The results obtained in this analysis suggests that data collected in the first 7 h are critical for the definition of the process of blood clearance and related parameters, whereas reliable information at later times is required for a proper characterisation of urinary excretion.

Assessment of intestinal absorption of trace metals in humans by means of stable isotopes

This study is aimed to demonstrate the feasibility of stable isotopes for the assessment of reliable data on fractional intestinal absorption of trace metals in healthy humans. Among the various methods available, the double isotope technique, i.e. one isotope given orally together with the test substance to be investigated and another isotope injected intravenously to correct for retention and endogenous excretion of the particular trace metal, provides quantitative figures of intestinal absorption at reasonable expenses with regard to costs for materials and number of samples to be evaluated. The trace metals exemplarily included in this study, i.e. iron, cobalt and molybdenum show diverging relations between absorbed fractions and amounts administered which are indicative for different regulatory mechanisms of their body content. Food ligands influence the fractional absorption significantly so that the uptake from a composite meal cannot be derived from results on uptake from particular foodstuffs. Therefore, validated data on the behaviour of intestinal absorption will significantly contribute to a better understanding of human trace metal metabolism.

Kinetics of systemic ruthenium in human blood using a stable tracer

The biokinetics of ruthenium after oral and intravenous administration has been investigated in two human subjects using the stable isotope 101Ru as a tracer. Tracer concentrations in blood plasma have been determined using activation analysis with protons. The results presented here prove that the stable tracer technique is a valuable tool for obtaining relevant information about the biokinetics of ruthenium in humans. From these pilot studies, it may be argued that the clearance of systemic ruthenium from plasma is significantly slower than the predictions of the biokinetic model currently recommended by the International Commission on Radiological Protection (ICRP). The experimental data for the orally administered tracer, which reflect the gastrointestinal absorption process, differ from the curve derived from the ICRP model, suggesting that the uptake into the systemic circulation may be lower than predicted. On the basis of these preliminary data, investigations on a larger number of subjects with improvements in the experimental design are scheduled.

Determination of biokinetic parameters for ingestion of radionuclides of zirconium in animals using stable tracers

Exposure to the radioactive isotope 95Zr, as in nuclear accidents, and to stable zirconium, due to its use in industry, has increased the interest in the biokinetics of this element. Information has been derived mainly from tests performed on animals by means of radioactive tracers. Due to the fact that extrapolation from animals to humans is always open to question, there is an increasing need of a methodology which allows data to be obtained directly from humans. The use of stable tracers, being ethically justifiable, is a powerful tool for providing this information. As two tracers of the same element must be utilized in order to evaluate gut absorption, an analytical technique which is capable of distinguishing and measuring simultaneously different isotopes of zirconium in biological samples is required. Preliminary tests on laboratory animals were performed in order to assess the feasibility of the double tracer technique combined with proton activation analysis.

Internal dose for ingestion of molybdenum radionuclides based on a revised biokinetic model

Recent investigations with human volunteers showed that the model recommended by ICRP for the description of the biokinetics of molybdenum radionuclides is not able to describe some characteristic features, like the clearance from the transfer compartment and the urinary excretion profile. Therefore, a revision of the model was presented in a previous paper. In the current work, dose coefficients for ingestion of radionuclides of molybdenum from members of the public have been calculated according to the ICRP guidelines, but using the revised biokinetic model. The results obtained for the effective dose do not differ remarkably from the ICRP estimates. However, considerable deviations are observed for the equivalent dose to some individual organs; for example, the dose coefficient for colon after ingestion of 99Mo in solid form is about 7 times higher than the ICRP value, whereas for other organs the new estimates are about one tenth of the ICRP ones. This fact could be of importance with respect to deterministic effects to particularly radiosensitive organs.

Internal biokinetic behaviour of molybdenum in humans studied with stable isotopes as tracers

Although molybdenum is considered to be an essential trace metal for humans, the knowledge about its metabolism is rather limited. The present study was aimed at the assessment of biokinetics following intravenous injection of trace amounts of 95Mo or 96Mo into five healthy volunteers. In a total of 11 investigations, the plasma clearance up to eight hours and the urinary excretion for at least three days after the injection were evaluated. The tracer concentrations were determined by proton nuclear activation analysis in blood plasma and by thermal ionization mass spectrometry in urine samples respectively. In all subjects, the plasma clearance is much faster than expected from the literature. The data obtained for the plasma clearance of the tracer can reasonably be fitted by a two exponential equation. The half times of the fast component range between 4 and 70 minutes and for the slow component between 3 and 30 hours. The urinary excretion of the injected tracer seems also to be faster than expected and the fractions lost are higher for larger doses administered. For the smallest dose given, 34% of the injected tracer were excreted within one day whereas for the four times larger dose about 60% were lost. These findings on urinary excretion are in agreement with recently published results.

Dose-response curve slope improvement and result reproducibility of ferrous-sulphate-doped gels analysed by NMR imaging

Ferrous sulphate gel analysed by relaxation time measurements with NMR imaging is considered a useful dosimeter for 3D determinations of absorbed dose. A protocol for the gel preparation with agarose SeaPlaque that leads to a dosimeter with very high dose sensitivity is described. The dose-response curve slope is about 0.2 s(-1) Gy(-1) and the G factor turns out to be approximately 185 ions per 100 eV of absorbed energy. A method for making the measurements and analysing the results that brings about good result reproducibility is suggested. A thorough experimental study of the dependence of the dosimeter response on the elapsed time from preparation to irradiation and from irradiation to NMR measurement has revealed good reproducibility. The above characteristic of the gel system is very interesting, because it shows the possibility of utilizing the dosimeter for absolute dose determinations with satisfactory reliability.

A revised model of molybdenum biokinetics in humans for application in radiation protection

The biokinetic models used to describe the fate of radionuclides incorporated by humans often lack the support of reliable experimental evidence. Recent investigations conducted in human volunteers using stable isotopes as tracers have shown that some important features of the biokinetics of ingested molybdenum are not taken into account by the model currently adopted by the International Commission on Radiological Protection. Compartmental analysis has been used to develop an improved model which better describes the available data. Major modifications with respect to the International Commission on Radiological Protection model concern the description of the urinary excretion and the values of the transfer parameters describing intestinal absorption and distribution to organs. Separate sets of parameter values for liquid and solid materials are also given.

Use of charged particle activation as an analytical technique in the biological field

Some applications of Charged Particle Activation Analysis (CPAA) in the biological field are presented. This technique has been used frequently for the analysis of the light elements which are inaccessible to neutron activation analysis (NAA), but it is especially effective in the detection of medium-heavy trace elements and there is increasing interest in its employment in biological and medical fields. CPAA enables the identification and simultaneous quantification of different isotopes of the same element. Recent applications show that it can be used as a reference method in stable isotope determination for biokinetic studies of selected elements in complex organic matrices such as blood plasma.

A methodology for biokinetic studies using stable isotopes: results of repeated molybdenum investigations on a healthy volunteer

A method for biokinetic studies in humans using stable isotopes is presented. The technique is based on double tracer administration and on proton activation as the analytical method. As an application, the results of investigations on molybdenum metabolism in humans are reported. The contents of 95Mo and 96Mo in biological samples were determined by inducing (p,n) reactions and by analysing the gamma-rays emitted by the radioactive products. The minimum detectable quantity was 2 ng/mL plasma for both Mo isotopes. Four investigations on molybdenum metabolism were performed on a healthy volunteer subject in the course of 3 yr. Two absorption studies with different amounts of tracers in aqueous solution were performed by giving 96Mo orally and 95Mo intravenously. Two investigations were performed with single oral administration of 96Mo in aqueous solution and of a 96Mo solution mixed with an infant formula respectively. The stability with time of the biokinetic parameters was tested. The fractional absorption values measured in this volunteer were 0.84, 0.98 and 0.95 for three studies with Mo in HCl and 0.51 for a single study with Mo administered in an infant formula, these data are discussed.

Influence of the administered mass of tellurium on plasma clearance in rabbits

The combination of analytical techniques such as PNA and SIMS with a compartmental approach enables the study of the metabolism and biokinetics in humans of several elements by using stable isotopes as tracers. The techniques developed for Te require the administration of greater masses than those used for similar studies performed with radioactive tracers, therefore a test was carried out in rabbits in order to assess the possible influence of the administered amounts on the determination of the biokinetic parameters. The behaviour of the tracers was found to be similar for Te administration of up to 70 micrograms/kg of body weight. An inter-individual variability in the size of the transfer compartment was observed and has to be taken into account.

Proton activation analysis of stable isotopes for a molybdenum biokinetics study in humans

Molybdenum is a trace element essential to life. Nevertheless, little information is available on its metabolism in humans. A methodology based on stable isotope administration that combines compartmental analysis, simultaneous use of two tracers, and proton nuclear activation (PNA) is presented. A four-compartment metabolic model was adopted. The compartments are stomach, small intestine, transfer compartment, and unquantified tissue pool. The employment of two different stable isotopes of the element under investigation as tracers was made possible by PNA. Optimization of the technique for molybdenum determination in plasma led to the choice of 95Mo and 96Mo as tracers. Their concentrations in plasma can be determined measuring the disintegration gamma lines of the corresponding technetium radioisotopes produced via (p,n) reaction. In the adopted experimental conditions, a minimum detectable concentration of 2 ng isotope/ml plasma was attained. A kinetics study was performed on two healthy volunteers. To both subjects one tracer was orally administered, and the other intravenously injected. Venous blood samples were withdrawn at different postinjection times and the concentrations for both isotopes determined. The model parameters describing molybdenum kinetics were obtained for the two individuals. Total absorbed fraction was found to be 0.84 +/- 0.03 and 0.86 +/- 0.07, respectively.

Response to a single oral test of molybdenum stable isotopes for absorption studies in humans

Two volunteer subjects were given orally enriched solutions of Mo-95 and Mo-96 respectively. Blood samples were drawn at various times following the tracer administration. The Mo-95 and Mo-96 content in plasma samples was determined by proton nuclear activation and the response to the single oral test of enriched stable molybdenum isotopes was determined. Assuming a simple two-open-compartment model where the first compartment is the gastrointestinal tract and the other is the plasma, an indicative value of the fractional intestinal absorption for the two subjects is given. The feasibility of direct quantitative measurements of Mo intestinal absorption by the double-tracer technique, using stable tracers, is evidenced.

Molybdenum metabolism studied by means of stable tracers

An investigation on molybdenum metabolism by administration of molybdenum stable isotopes was performed. Fractional intestinal absorption was determined in animals by the double tracer technique. The investigated subjects were given an enriched solution of Mo-96 orally and, a few minutes later, an enriched solution of Mo-95 intravenously. Blood samples were drawn at different times following the tracer administration. The Mo-95 and Mo-96 contents in plasma samples were determined by proton nuclear activation. The described methodology offers a means for the study of molybdenum metabolism in humans without radiation risk.

An iron metabolism study in humans by means of stable tracers

An investigation of iron metabolism in a female patient volunteer by administration of stable iron isotopes as tracers was performed. The applied methodology had already been tested in rabbits in comparison with radioactive tracer technique. The subject under study was given 58Fe solution intravenously and about 45 min later 57Fe solution orally. Ten blood samples were drawn at different times within 522 min from injection. Single iron isotopes content in plasma samples was determined by proton nuclear activation. A Compton suppressor system was utilized to improve the detector limits. The characteristic parameters of iron plasma clearance and of iron intestinal absorption were determined.

Ferrokinetic studies with stable isotopes as tracers

A methodology for ferrokinetic studies based on the administration of iron stable isotopes was developed. Fractional plasma clearance and intestinal iron absorption in rabbits were determined using the double tracer technique. Three rabbits were given 58Fe solution intravenously and about 40 min later 57Fe solution orally. Blood samples were drawn at different times following administration. The analysis of the single iron isotopes content in plasma samples was made by proton nuclear activation. The results were compared with those obtained from the administration, to the same rabbits, of the radioactive isotopes 55Fe and 59Fe. The agreement was found to be satisfactory.

[Strain gauges for measuring the tension at the site of sutures. Use of the original instrument with a personal technic]

The Authors have developed an instrumentation suitable for suture line tension measuring during plastic operations for large incisional hernias. A full description is given of the measuring technique and of the original instrumentation, including two steel bars called "fachiri" and an electric measuring system with strain gauges. With the employment of this technique, relaxing incisions of the muscle aponeurosis can be reduced to the minimum. Being the suture line tension one of the most important causes of relapsing, the Authors believe that this technique provides a sure advantage for the long term results of plastic operations.

Trace elements analysis in biological samples by proton nuclear activation

A method for the multielemental analysis of trace elements in biological samples by medium energy proton nuclear activation (PNA) has been developed. The response linearity, reproducibility and reliability of the method have been tested by a set of preliminary measurements. Results concerning the quantitative determination of the concentrations of Sr, Cu, Fe, Zn and Se in human serum are presented. Activation was induced with a 23 MeV proton beam from the AVF cyclotron of the University of Milan, by means of (p, 2n) reactions on the nuclei of the elements under study. The quantitative determination was obtained by an internal reference method and by comparison with a standard sample of serum doped with known quantities of the elements of interest. A clinical investigation of the zinc content of serum in children has been performed.