Performance assessment and uncertainty evaluation of a portable NaI-based detection system used for thyroid monitoring

This work aims at assessing the performance of a portable detection system, equipped with an NaI(Tl) scintillation detector for in vivo thyroid monitoring, which was properly calibrated using an anthropomorphic neck phantom. The anthropomorphic physical phantoms commonly used for the efficiency calibration of in vivo counters often present certain limitations regarding the geometry and the activity distribution. Therefore, the feasibility of these detection systems for in vivo monitoring should be assessed whenever possible. To accomplish this assessment, patients to whom (99m)Tc and (123)I marked radiopharmaceuticals have been administered in the framework of nuclear medicine diagnostic procedures were monitored. As the biokinetic models of the administered radiopharmaceuticals are known, the time-dependent activity functions in the critical organs after administration are easily quantified. The measured activities in the thyroid using the NaI(Tl) scintillation detector were compared with the estimated activities using the biokinetic models, in order to reach conclusion about the applicability of the portable scintillation counter for in vivo thyroid monitoring. The state-of-the-art Monte Carlo computer program PENELOPE and two voxel phantoms (male and female) were used to evaluate the overall uncertainties influencing the thyroid monitoring. A computational parametric study was performed to quantify the influence of several parameters in the activity quantification (neck-detector distance, thyroid shape, thyroid size and overlying tissue thickness), which allowed one to gain insight and to better understand the discrepancies between the calculated and measured activities.

Study of nuclear medicine practices in Portugal from an internal dosimetry perspective

Nuclear medicine practices involve the handling of a wide range of pharmaceuticals labelled with different radionuclides, for diagnostic and therapeutic purposes. This work intends to evaluate the potential risks of internal contamination of nuclear medicine staff in several Portuguese nuclear medicine services and to conclude about the requirement of a routine internal monitoring. A methodology proposed by the International Atomic Energy Agency (IAEA), providing a set of criteria to determine the need, or not, for an internal monitoring programme, was applied. The evaluation of the risk of internal contaminations in a given set of working conditions is based on the type and amount of radionuclides being handled, as well as the safety conditions with which they are manipulated. The application of the IAEA criteria showed that 73.1% of all the workers included in this study should be integrated in a routine monitoring programme for internal contaminations; more specifically, 100% of workers performing radioimmunoassay techniques should be monitored. This study suggests that a routine monitoring programme for internal exposures should be implemented in Portugal for most nuclear medicine workers.

Thermolabile liposomes: a controlled release delivery tool in diagnosis/therapy in experimental pulmonary ɶdema

Liposomes, usually assembled from organic/synthetic lipidic compounds, are biocompatible, biodegradable, non-toxic, and do not induce immune response. Due to their structural versatility in terms of size, composition, surface charge, bilayer fluidity and ability to encapsulate drugs regardless of their solubility, liposomes enable the production of a vast number and type of formulations with potential clinical use. They can be administered through several routes of administration (e.g. i.v., i.m., oral, nasal, etc.). The use of liposomes enables the variation and control retention of drugs in biologic fluids, enhancing blood circulation and specific compartments residence. They can be tailored to target specific tissues and cells. They can play a very important role for imaging diagnosis and/or therapy. After an extensive literature review of the subject, we selected a particular area of potential clinical application: pulmonary ɶdema. This clinical entity has a variety of possible etiologies, conducing to two main types of edema: cardiogenic and non-cardiogenic. At the moment a dedicated technique for the early diagnosis/therapy of this pathology is lacking. We propose a new methodology using a specially designed GUV formulation, encapsulating chosen radiotracers labeled with 99mTc. The aim of the work has been successfully achieved in an experimental animal model of cardiogenic pulmonary oedema. Experiments using an animal model of non-cardiogenic pulmonary oedema are in course (simultaneous study with two different drugs), using the same GUV methodology. Preliminary results are very promising.

[Androgen deprivation therapy and morbid obesity: do they share cardiovascular risk through metabolic syndrome?]

BACKGROUND

Although the use of androgen deprivation therapy (ADT) has resulted in improved survival in men with advanced prostate cancer, the resulting hypogonadism is associated with profound adverse effects comparable to those found in morbid obesity, being cardiovascular risk among the most lethal.

OBJECTIVES

Evaluate metabolic syndrome, metabolic abnormalities and cardiovascular risk in patients with prostate cancer under ADT, not under ADT and morbid obese men.

METHODS

This is a cross-sectional study that involves 79 men presenting prostate cancer, of whom 54 under ADT and 25 not under ADT and 91 morbidly obese patients paired by sex and age. To define metabolic syndrome, we used the International Diabetes Federation (IDF) criteria. Metabolic abnormalities, metabolic markers and Framingham score to predict the ten year coronary heart disease risk were compared among patients under ADT, not under ADT and morbid obese.

RESULTS

Patients under ADT presented significantly greater occurrence of diabetes and central obesity and higher levels of total cholesterol and low density lipoprotein (LDL) compared to eugonadal men. The mean cardiovascular risk was significantly higher in patients under ADT (39.97±12.53% vs. 26.09±14.80%; p=0.021). Morbidly obese subjects had increased ten year coronary heart disease risk; comparable to patients under ADT (p=0.054).

CONCLUSION

This study suggests that patients under ADT show higher prevalence of metabolic abnormalities and cardiovascular risk similar to those found in morbidly obese subjects. It is possible that both processes share cardiovascular risk through metabolic syndrome.

Incidence of adverse events associated with percutaneous muscular biopsy among healthy and diseased subjects

The development of the percutaneous muscle biopsy technique is recognized as one of the most important scientific contributions in advancing our understanding of skeletal muscle physiology. However, a concern that this procedure may be associated with adverse events still exists. We reported the incidence of adverse outcomes associated with percutaneous muscle biopsy in healthy and diseased subjects. Medical records of 274 volunteers (496 muscle biopsies) were reviewed. This included 168 healthy subjects (330 muscle biopsies) as well as 106 chronically ill patients (166 muscle biopsies). This latter group encompassed patients with type II diabetes (n=28), osteoarthritis (n=39), inclusion body myositis (n=4), polymyositis (n=4), and chronic heart failure (n=31). The most common occurrences were pain (1.27%), erythema (1.27%), and ecchymosis (1.27%). Panic episode, bleeding, and edema were also reported (0.21%, 0.42%, and 0.84%, respectively), while infection, hematoma, inflammation, denervation, numbness, atrophy, and abnormal scarring were not verified. The percent of incidents did not differ between healthy and ill individuals. In conclusion, the incidence of complications associated with percutaneous muscle biopsy is scarce and of minor clinical relevance. Additionally, the rate of adverse events is comparable between healthy and chronically ill subjects.

Chronic myeloid leukaemia in two multiple sclerosis patients on interferon beta-1a

Haematological problems are commonly associated with use of beta-interferon in multiple sclerosis (MS) patients. However these problems are usually benign and are reversible when the drug is stopped. We describe two patients, with the diagnosis of MS, who developed leucocytosis. Cytogenetic studies showed the presence of the Philadelphia chromosome in all the cells analysed, confirming the diagnosis of chronic myeloid leukaemia (CML). The first patient currently on imatimib mesylate and interferon beta-1a is asymptomatic. For the second patient, interferon beta-1a was withdrawn after suspicion of CML.

Lymphatic uptake of lipid nanoparticles following endotracheal administration

A previous publication reported the uptake into the lymphatics of pulmonary administered lipid nanoparticles (LN), after aerosolization and inhalation. In the present study LN clearance from the lungs and lymphatic uptake were further evaluated after endotracheal administration. Nanoparticles prepared with gliceryl behenate were radiolabelled by association to the lipophilic tracer D,L-hexamethylpropylene amine oxime (HMPAO) coupled with 99mTc. Labelling efficiency was 97% and stability in body fluids was demonstrated in vitro. Wistar rats were treated by endotracheal administration and lymphatic uptake was determined upon organ sampling. Endotracheally delivered LN are rapidly eliminated from rat lungs and accumulation in para-aortic, axillary and inguinal lymph nodes starts almost immediately after administration. Translocation of LN across the lung mucosa and their uptake into the lymphatics demonstrate their usefulness as potential drug carriers for lung cancer therapy, as well as for immunization purposes.

Overview of BioCreative II gene mention recognition

Nineteen teams presented results for the Gene Mention Task at the BioCreative II Workshop. In this task participants designed systems to identify substrings in sentences corresponding to gene name mentions. A variety of different methods were used and the results varied with a highest achieved F₁ score of 0.8721. Here we present brief descriptions of all the methods used and a statistical analysis of the results. We also demonstrate that, by combining the results from all submissions, an F score of 0.9066 is feasible, and furthermore that the best result makes use of the lowest scoring submissions.

Targeting of lanthanide(III) chelates of DOTA-type glycoconjugates to the hepatic asyaloglycoprotein receptor: cell internalization and animal imaging studies

The characterization of a new class of hydrophilic liver-targeted agents for gamma-scintigraphy and MRI, consisting, respectively, of [(153)Sm](3+) or Gd(3+) complexes of DOTA monoamide or bisamide linked glycoconjugates (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), is reported. In vitro studies show high uptake of radiolabeled [(153)Sm]-DOTAGal(2) by the human hepatocyte carcinoma cell line Hep G2 containing the asialoglycoprotein receptor (ASGP-R), which is decreased to less than 50% by the presence of its high-affinity ligand asialofetuin (ASF). In vivo biodistribution, gamma-imaging and pharmacokinetic studies on Wistar rats using the [(153)Sm](3+)-labeled glycoconjugates show a high uptake in the receptor-rich organ liver of the radiolabeled compounds containing terminal galactosyl groups, but very little uptake for those compounds with terminal glycosyl groups. Blocking the receptor in vivo reduced liver uptake by 90%, strongly suggesting that the liver uptake of these compounds is mediated by their binding to the asyaloglycoprotein receptor (ASGP-R). This study also demonstrated that the valency increase improves the targeting capability of the glycoconjugates, which is also affected by their topology. However despite the specific liver uptake of the radiolabeled galactose-bearing multivalent compounds, the animal MRI assessment of the corresponding Gd(3+) chelates shows liver-to-kidney contrast effects which are not significantly better than those shown by GdDTPA. This probably results from the quick wash-out from the liver of these highly hydrophilic complexes, before they can be sufficiently concentrated within the hepatocytes via receptor-mediated endocytosis.