The evidence-based role of catecholaminergic PET tracers in Neuroblastoma. A systematic review and a head-to-head comparison with mIBG scintigraphy

BACKGROUND

Molecular imaging is pivotal in staging and response assessment of children with neuroblastoma (NB). [123I]-metaiodobenzylguanidine (mIBG) is the standard imaging method; however, it is characterised by low spatial resolution, time-consuming acquisition procedures and difficult interpretation. Many PET catecholaminergic radiotracers have been proposed as a replacement for [123I]-mIBG, however they have not yet made it into clinical practice. We aimed to review the available literature comparing head-to-head [123I]-mIBG with the most common PET catecholaminergic radiopharmaceuticals.

METHODS

We searched the PubMed database for studies performing a head-to-head comparison between [123I]-mIBG and PET radiopharmaceuticals including meta-hydroxyephedrine ([11C]C-HED), 18F-18F-3,4-dihydroxyphenylalanine ([18F]DOPA) [124I]mIBG and Meta-[18F]fluorobenzylguanidine ([18F]mFBG). Review articles, preclinical studies, small case series (< 5 subjects), case reports, and articles not in English were excluded. From each study, the following characteristics were extracted: bibliographic information, technical parameters, and the sensitivity of the procedure according to a patient-based analysis (PBA) and a lesion-based analysis (LBA).

RESULTS

Ten studies were selected: two regarding [11C]C-HED, four [18F]DOPA, one [124I]mIBG, and three [18F]mFBG. These studies included 181 patients (range 5-46). For the PBA, the superiority of the PET method was reported in two out of ten studies (both using [18F]DOPA). For LBA, PET detected significantly more lesions than scintigraphy in seven out of ten studies.

CONCLUSIONS

PET/CT using catecholaminergic tracers shows superior diagnostic performance than mIBG scintigraphy. However, it is still unknown if such superiority can influence clinical decision-making. Nonetheless, the PET examination appears promising for clinical practice as it offers faster image acquisition, less need for sedation, and a single-day examination.

Spontaneous Remission of High-Grade Non-Hodgkin Lymphoma After SARS-CoV-2 Infection: A Case Report

ABSTRACT

Despite extensive research into COVID-19 since its emergence in late 2019, there is still much not fully understood about its long-term effects. When infected with SARS-CoV-2, cancer patients have been reported to be at higher risk for unfavorable outcomes. Nevertheless, evidence suggests that viruses may exhibit an antitumor effect in some cases, which has recently been anecdotally reported with SARS-CoV-2. We present the case of a patient with a recent high-grade non-Hodgkin lymphoma diagnosis and without any cancer-specific therapy, in whom a complete metabolic response on 2-[ 18 F]FDG PET/CT was observed after COVID-19.

Colorectal cancer cell exosome and cytoplasmic membrane for homotypic delivery of therapeutic molecules

Colorectal cancer (CRC) is one of the most common causes of death in the world. The multi-drug resistance, especially in metastatic colorectal cancer, drives the development of new strategies that secure a positive outcome and reduce undesirable side effects. Nanotechnology has made an impact in addressing some pharmacokinetic and safety issues related to administration of free therapeutic agents. However, demands of managing complex biointerfacing require equally complex methods for introducing stimuli-responsive or targeting elements. In order to procure a more efficient solution to the overcoming of biological barriers, the physiological functions of cancer cell plasma and exosomal membranes provided the source of highly functionalized coatings. Biomimetic nanovehicles based on colorectal cancer (CRC) membranes imparted enhanced biological compatibility, immune escape and protection to diverse classes of therapeutic molecules. When loaded with therapeutic load or used as a coating for other therapeutic nanovehicles, they provide highly efficient and selective cell targeting and uptake. This review presents a detailed overview of the recent application of homotypic biomimetic nanovehicles in the management of CRC. We also address some of the current possibilities and challenges associated with the CRC membrane biomimetics.

Beyond the Bones: A Case Report of Extraosseous Ewing Sarcoma

Ewing sarcoma (ES) is primarily recognized as a primary bone tumor; however, its extraosseous variant is exceptionally rare and presents unique clinical challenges. In this article, we report the case of a 22-year-old male who initially presented with abdominal swelling. Diagnostic tests included abdominal imaging and a CT scan, revealing a solid liver mass. A thorough evaluation confirmed it to be an extraosseous ES, supported by liver biopsy and immunohistochemistry demonstrating positive expression for AE1/AE3 and CD-99, along with genetic analysis revealing a rearrangement of the EWSR1 gene (translocation 22q12). The patient's treatment involved a multimodal approach, including perioperative chemotherapy, surgery, and postoperative chemotherapy, following which the patient remained in complete remission after 24 months. This case emphasizes the importance of considering rare malignancies such as ES in differential diagnoses for young patients with liver masses. It also accentuates the pivotal role of family physicians in early detection and holistic patient care, underscoring the need for comprehensive investigations when encountering persistent symptoms.

Triple Therapy for Cystic Fibrosis (Elexacaftor, Tezacaftor, and Ivacaftor): Desensitization After Skin Rash

Cystic fibrosis (CF) is an autosomal recessive disorder of the CF transmembrane conductance regulator (CFTR) gene. CFTR modulators are novel approved therapies, and triple therapy with elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) is the current gold standard for patients with at least one F508del mutation. CFTR modulators are usually well-tolerated, but some adverse effects may occur, including skin rash. We report a case of a female patient who developed a severe skin rash after initiating treatment with ELX/TEZ/IVA. Modulator therapy and contraception were discontinued, and consequently, there was a drop in lung function and reappearance of respiratory symptoms. After rash resolution, a gradual reintroduction of ELX/TEZ/IVA was started, and this is the protocol the authors have summarized. Triple therapy with CFTR modulators has a significant impact on lung function and the quality of life of CF patients who have at least one F508del mutation, justifying its reintroduction and desensitization even after a severe adverse effect.

A simple interactive robot to promote computational thinking

This paper described the functionalities of a simple robot adopted in the classroom to promote computational thinking (CT) in the context of the project PeCOT—computational thinking with tangible objects. This robot, similar to some commercial educational robots, was developed to be used in primary education classroom contexts (second, third, and fourth grades) by children between 8 and 10 years old. PeCOT is a pedagogical intervention project and research project that will run over the next 2 years. The aim of this paper is to present the robot, how it works, and some activities that can be implemented in the educational context to promote CT skills, including learning in different subject areas, such as mathematics or natural science. Thus, we begin by presenting a general description of the robot. Next, we identify activities and formalize the programming steps for each of the activities. Finally, we discuss the potential that the robot and the proposed activities may have to promote the development of CT skills.

Educational Robotics and Tangible Devices for Promoting Computational Thinking

Recently, efforts have been made to add programming activities to the curriculum that promote computational thinking and foster 21st-century digital skills. One of the programming modalities is the use of Tangible Programming Languages (TPL), used in activities with 4+ year old children. In this review, we analyze solutions proposed for TPL in different contexts crossing them with non-TPL solutions, like Graphical Programming Languages (GPL). We start to characterize features of language interaction, their use, and what learning activities are associated with them. Then, in a diagram, we show a relation between the complexity of the languages with factors such as target age and output device types. We provide an analysis considering the type of input (e.g., TPL versus GPL) and output devices (e.g., physical robot versus graphical simulation) and evaluate their contribution to further insights about the general trends with respect to educational robotic systems. Finally, we discuss the opportunities to extend and improve TPLs based on the different solutions identified.

Identification of new targets of S-nitrosylation in neural stem cells by thiol redox proteomics

Nitric oxide (NO) is well established as a regulator of neurogenesis. NO increases the proliferation of neural stem cells (NSC), and is essential for hippocampal injury-induced neurogenesis following an excitotoxic lesion. One of the mechanisms underlying non-classical NO cell signaling is protein S-nitrosylation. This post-translational modification consists in the formation of a nitrosothiol group (R-SNO) in cysteine residues, which can promote formation of other oxidative modifications in those cysteine residues. S-nitrosylation can regulate many physiological processes, including neuronal plasticity and neurogenesis. In this work, we aimed to identify S-nitrosylation targets of NO that could participate in neurogenesis. In NSC, we identified a group of proteins oxidatively modified using complementary techniques of thiol redox proteomics. S-nitrosylation of some of these proteins was confirmed and validated in a seizure mouse model of hippocampal injury and in cultured hippocampal stem cells. The identified S-nitrosylated proteins are involved in the ERK/MAPK pathway and may be important targets of NO to enhance the proliferation of NSC.

FELASA accreditation of education and training courses in laboratory animal science according to the Directive 2010/63/EU

This document describes how the Federation of European Laboratory Animal Science Associations (FELASA) accreditation addresses both the Directive 2010/63/EU and the related European Commission guidance document.

S-Nitrosylation of Ras Mediates Nitric Oxide-Dependent Post-Injury Neurogenesis in a Seizure Model

AIMS

Nitric oxide (NO) is involved in the upregulation of endogenous neurogenesis in the subventricular zone and in the hippocampus after injury. One of the main neurogenic pathways activated by NO is the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway, downstream of the epidermal growth factor receptor. However, the mechanism by which NO stimulates cell proliferation through activation of the ERK/MAPK pathway remains unknown, although p21Ras seems to be one of the earliest targets of NO. Here, we aimed at studying the possible neurogenic action of NO by post-translational modification of p21Ras as a relevant target for early neurogenic events promoted by NO in neural stem cells (NSCs).

RESULTS

We show that NO caused S-nitrosylation (SNO) of p21Ras in Cys118, which triggered downstream activation of the ERK/MAPK pathway and proliferation of NSC. Moreover, in cells overexpressing a mutant Ras in which Cys118 was replaced by a serine-C118S-, cells were insensitive to NO, and no increase in SNO, in ERK phosphorylation, or in cell proliferation was observed. We also show that, after seizures, in the presence of NO derived from inducible nitric oxide synthase, there was an increase in p21Ras cysteine modification that was concomitant with the previously described stimulation of proliferation in the dentate gyrus.

INNOVATION

Our work identifies p21Ras and its SNO as an early target of NO during signaling events that lead to NSC proliferation and neurogenesis.

CONCLUSION

Our data highlight Ras SNO as an early event leading to NSC proliferation, and they may provide a target for NO-induced stimulation of neurogenesis with implications for brain repair. Antioxid. Redox Signal. 28, 15-30.

Assessment of the Absorbed Dose in the Kidney of Nuclear Nephrology Paediatric Patients using ICRP Biokinetic Data and Monte Carlo Simulations with Mass-Scaled Paediatric Voxel Phantoms

The aim of this work is to use Monte Carlo simulations and VOXEL phantoms to estimate the absorbed dose in paediatric patients (aged from 2 weeks to 16 y), with normal renal function, to whom technetium-99m-dimercaptosuccinic acid (99mTc-DMSA) was administered, for diagnostic renal scintigraphy purposes; and compare them with values obtained using the International Commission on Radiological Protection (ICRP) methodology. In the ICRP methodology, the cumulated absorbed dose in the kidneys is estimated by multiplying the administered activity with the corresponding given dose coefficients. The other methods were based on Monte Carlo simulations performed on two paediatric voxel phantoms (CHILD and BABY), and another three phantoms, which were modified to suit the mass of the patients' kidneys, and other anatomical factors. Different S-values were estimated using this methodology, which together with solving the ICRP biokinetic model to determine the cumulated activities, allowed for the estimation of absorbed doses different from those obtained with the ICRP method, together with new dose coefficients. The obtained values were then compared. The deviations suggest that the S-values are strongly dependent on the patient's total body weight, which could be in contrast with the ICRP data, which is provided by age, regardless of other anatomical parameters.

Pulmonary ventilation/perfusion single photon emission tomography--Initial experience of a Nuclear Medicine Department

INTRODUCTION

Lung ventilation/perfusion scintigraphy with planar images (V/QS-planar) is very useful for the diagnosis and follow-up of pulmonary thromboembolism (PTE). Acquiring tomographic images (V/QS-SPECT) is a recent development with potential to increase the technique's accuracy. The purpose of this work is to evaluate the added benefits of V/QS-SPECT studies as opposed to traditional planar imaging.

PATIENTS AND METHODS

We prospectively revised 53 V/QS-planar and V/QS-SPECT exams, performed according to the European Association of Nuclear Medicine guidelines. We evaluated the exams independently, by consensus of two Nuclear Medicine physicians. For both methods, we gave each lung a score expressing the dimension and extension of perfusion defects with normal ventilation. For each lung, we compared the scores with the paired Wilcoxon test, estimating the 95% confidence interval (95 CI) for the respective difference.

RESULTS

We performed V/QS-SPECT exams without technical difficulties. The paired Wilcoxon test estimated the score difference to be -0.75 (95 CI of -1.0 to -0.5; p-value=9.6 × 10(-7)), expressing a statistically significant difference of about 1 subsegmental defect between both methods, with V/QS-SPECT detecting more defects.

DISCUSSION

The results demonstrate that V/QS-SPECT identifies a slightly larger number of perfusion defects than V/QS-planar, suggesting a higher sensitivity of this technique. However, more studies are necessary to evaluate the clinical meaning of this fact.

CONCLUSION

V/QS-SPECT demonstrates a higher capability to identify perfusion defects. This method looks promising, allowing for a greater role of this exam in pulmonary thromboembolism diagnosis and follow-up.

S-nitrosation and neuronal plasticity

Nitric oxide (NO) has long been recognized as a multifaceted participant in brain physiology. Despite the knowledge that was gathered over many years regarding the contribution of NO to neuronal plasticity, for example the ability of the brain to change in response to new stimuli, only in recent years have we begun to understand how NO acts on the molecular and cellular level to orchestrate such important phenomena as synaptic plasticity (modification of the strength of existing synapses) or the formation of new synapses (synaptogenesis) and new neurons (neurogenesis). Post-translational modification of proteins by NO derivatives or reactive nitrogen species is a non-classical mechanism for signalling by NO. S-nitrosation is a reversible post-translational modification of thiol groups (mainly on cysteines) that may result in a change of function of the modified protein. S-nitrosation of key target proteins has emerged as a main regulatory mechanism by which NO can influence several levels of brain plasticity, which are reviewed in this work. Understanding how S-nitrosation contributes to neural plasticity can help us to better understand the physiology of these processes, and to better address pathological changes in plasticity that are involved in the pathophysiology of several neurological diseases.

Conceções dos educadores portugueses sobre a linguagem escrita: um estudo de caso || Conceptions of the Portuguese Preschool teachers about writing language: a case study

O presente artigo pretende dar conta dos resultados de uma investigação realizada junto de um grupo de 18 educadoras de infância a trabalhar na em escolas da rede pública da Ilha Terceira, Açores, Portugal, cujo objetivo foi o de compreender a sua perspetiva acerca da abordagem à linguagem escrita no âmbito da educação de infância. Foram avaliados aspetos como a posição pedagógica e metodológica que as educadoras afirmam adotar na sua intervenção pedagógica e os processos de aprendizagem que afirmam privilegiar como promotores da literacia nas suas salas. A entrevista realizada durante o segundo trimestre do ano escolar permitiu concluir que a forma de pensar destas educadoras, acerca do desenvolvimento da linguagem escrita, caracteriza-se, basicamente, pelo distanciamento relativamente a uma perspetiva emergente da literacia, centrada nas crianças, pela atribuição de uma acentuada importância às atividades e estratégias de intervenção direta e pelo défice de conhecimentos sobre a forma como se desenvolvem os processos de leitura e escrita em crianças pré-escolares.

Renal radionuclide imaging, an evergreen forty years old

Urinary tract congenital abnormalities (UCA) and febrile infections (UTI) are, respectively, 2 of the commonest congenital and acquired health problems in childhood. In both, radionuclide imaging still represent a cornerstone of diagnostic imaging, although the involved techniques are more or less the same from the early '80 s. During the last 2 decades, published papers focused on a deep revision about the optimal use and usefulness of such imaging tools in affected children, with the aim of reducing invasiveness, radiation burden and costs without losing efficacy. This approach leads to different results. In UCA, no consensus for a diagnostic algorithm was up to now reached, whilst, about febrile UTIs, guidelines were published in 2007 by the UK's National Institute for Clinical Excellence (NICE) and by the European Society of Paediatric Radiology (ESPR), in 2011 by the American Academy of Paediatrics (AAP), and in 2012 by the Italian Society of Paediatric Nephrology (SINP). Nevertheless, new data continuously arise and the scientific debate always revives. Every imaging tool now available has its own strengths and weaknesses, and so all published guidelines. All this body of knowledge must be critically analysed for obtaining a complete, up-to-date and flexible overview about these "always hot" topics.

Relação do Tabagismo com Ansiedade e Depressão nos Cuidados de Saúde Primários

Introduction: Smoking prevalence in Portugal is estimated to be 19.7% (2005). Smoking is prevalent in anxiety disorders. Studies report that 60% of smokers have a history of depression. The Fagerström scale can be used to assess smoke dependence. The Hospital Anxiety and Depression Scale allows an estimate of anxiety and depression. Our goal was to find whether there is a relationship between smoking and anxiety / depression in eight clinics within primary care practice.Material and Methods: We designed an observational, descriptive, cross-sectional, analytical study. Anonymous survey. We considered as inclusion criteria the over 18 years of age and literate clinic users and as exclusion criteria the under 18 years old users or incomplete surveys. We defined as variables: Fagerström, Hospital Anxiety and Depression Scale, age, marital status, gender, profession, schooling.Results: We obtained a total of 608 valid surveys of which there were 64% women and 21% smokers. We found no differences in the prevalence of anxiety or depression when comparing non-smokers, ex-smokers and smokers. We found that the degree of nicotine addiction varies directly with anxiety and depression, however, the only statistically significant relationship observed was in women, even after correcting the effect of age.Discussion: There is a relationship between nicotine dependence and the severity of symptoms of anxiety and depression, most relevant in women. Limitation: selection bias.Conclusion: This study supplies information regarding psychological factors associated with tobacco consumption, allowing for its inclusion in treatment options for nicotine dependence.

[Relationship between smoking and anxiety and depression in primary care]

INTRODUCTION

Smoking prevalence in Portugal is estimated to be 19.7% (2005). Smoking is prevalent in anxiety disorders. Studies report that 60% of smokers have a history of depression. The Fagerström scale can be used to assess smoke dependence. The Hospital Anxiety and Depression Scale allows an estimate of anxiety and depression. Our goal was to find whether there is a relationship between smoking and anxiety / depression in eight clinics within primary care practice.

MATERIAL AND METHODS

We designed an observational, descriptive, cross-sectional, analytical study. Anonymous survey. We considered as inclusion criteria the over 18 years of age and literate clinic users and as exclusion criteria the under 18 years old users or incomplete surveys. We defined as variables: Fagerström, Hospital Anxiety and Depression Scale, age, marital status, gender, profession, schooling.

RESULTS

We obtained a total of 608 valid surveys of which there were 64% women and 21% smokers. We found no differences in the prevalence of anxiety or depression when comparing non-smokers, ex-smokers and smokers. We found that the degree of nicotine addiction varies directly with anxiety and depression, however, the only statistically significant relationship observed was in women, even after correcting the effect of age.

DISCUSSION

There is a relationship between nicotine dependence and the severity of symptoms of anxiety and depression, most relevant in women.

LIMITATION

selection bias.

CONCLUSION

This study supplies information regarding psychological factors associated with tobacco consumption, allowing for its inclusion in treatment options for nicotine dependence.

Estimation of the collective dose in the Portuguese population due to medical procedures in 2010

In a wide range of medical fields, technological advancements have led to an increase in the average collective dose in national populations worldwide. Periodic estimations of the average collective population dose due to medical exposure is, therefore of utmost importance, and is now mandatory in countries within the European Union (article 12 of EURATOM directive 97/43). Presented in this work is a report on the estimation of the collective dose in the Portuguese population due to nuclear medicine diagnostic procedures and the Top 20 diagnostic radiology examinations, which represent the 20 exams that contribute the most to the total collective dose in diagnostic radiology and interventional procedures in Europe. This work involved the collaboration of a multidisciplinary taskforce comprising representatives of all major Portuguese stakeholders (universities, research institutions, public and private healthcare providers, administrative services of the National Healthcare System, scientific and professional associations and private service providers). This allowed us to gather a comprehensive amount of data necessary for a robust estimation of the collective effective dose to the Portuguese population. The methodology used for data collection and dose estimation was based on European Commission recommendations, as this work was performed in the framework of the European wide Dose Datamed II project. This is the first study estimating the collective dose for the population in Portugal, considering such a wide national coverage and range of procedures and consisting of important baseline reference data. The taskforce intends to continue developing periodic collective dose estimations in the future. The estimated annual average effective dose for the Portuguese population was of 0.080±0.017 mSv caput(-1) for nuclear medicine exams and of 0.96±0.68 mSv caput(-1) for the Top 20 diagnostic radiology exams.

Microglial activation, increased TNF and SERT expression in the prefrontal cortex define stress-altered behaviour in mice susceptible to anhedonia

A chronic stress paradigm comprising exposure to predation, tail suspension and restraint induces a depressive syndrome in C57BL/6J mice that occurs in some, but not all, animals. Here, we sought to extend our behavioural studies to investigate how susceptibility (sucrose preference<65%) or resilience (sucrose preference>65%) to stress-induced anhedonia affects the 5HT system and the expression of inflammation-related genes. All chronically stressed animals, displayed increased level of anxiety, but susceptible mice exhibited an increased propensity to float in the forced swim test and demonstrate hyperactivity under stressful lighting conditions. These changes were not present in resilient or acutely stressed animals. Compared to resilient animals, susceptible mice showed elevated expression of tumour necrosis factor alpha (TNF) and the 5-HT transporter (SERT) in the pre-frontal area. Enhanced expression of 5HT(2A) and COX-1 in the pre-frontal area was observed in all stressed animals. In turn, indoleamine-2,3-dioxygenase (IDO) was significantly unregulated in the raphe of susceptible animals. At the cellular level, increased numbers of Iba-1-positive microglial cells were also present in the prefrontal area of susceptible animals compared to resilient animals. Consequently, the susceptible animals display a unique molecular profile when compared to resilient, but anxious, animals. Unexpectedly, this altered profile provides a rationale for exploring anti-inflammatory, and possibly, TNF-targeted therapy for major depression.

Effects of anaesthesia on insulin sensitivity and metabolic parameters in Wistar rats

We compared the effects of two different anaesthetics, sodium pentobarbital (65 mg/kg) and ketamine (30 mg/kg) plus xylazine (4 mg/kg) (KX) on insulin sensitivity, fasting glycaemia, insulinaemia and free fatty acids (FFA). Four groups of Wistar rats were used: KX group (n=6), pentobarbital group (n=6), high-sucrose diet group (n=6) and the conscious group (n=6). The insulin tolerance test (ITT) was used to measure insulin sensitivity, and metabolic biomarkers were determined using commercial kits. Pentobarbital did not alter plasma insulin, glucose, FFA or the ITT results compared to conscious animals. In contrast, KX anaesthesia induced hyperglycaemia, increased serum FFA and altered the ITT results compared to the conscious animal group. Moreover, under pentobarbital anaesthesia, the ITT proved to be a suitable method to detect insulin resistance in an animal model of diet-induced insulin resistance. We concluded that sodium pentobarbital anaesthesia should be used in metabolic studies since it does not interfere with plasma glucose, insulin, FFA or insulin sensitivity quantification in Wistar rats.

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.

Differential contribution of the guanylyl cyclase-cyclic GMP-protein kinase G pathway to the proliferation of neural stem cells stimulated by nitric oxide

Nitric oxide (NO) is an important inflammatory mediator involved in the initial boost in the proliferation of neural stem cells following brain injury. However, the mechanisms underlying the proliferative effect of NO are still unclear. The aim of this work was to investigate whether cyclic GMP (cGMP) and the cGMP-dependent kinase (PKG) are involved in the proliferative effect triggered by NO in neural stem cells. For this purpose, cultures of neural stem cells isolated from the mouse subventricular zone (SVZ) were used. We observed that long-term exposure to the NO donor (24 h), NOC-18, increased the proliferation of SVZ cells in a cGMP-dependent manner, since the guanylate cyclase inhibitor, ODQ, prevented cell proliferation. Similarly to NOC-18, the cGMP analogue, 8-Br-cGMP, also increased cell proliferation. Interestingly, shorter exposures to NO (6 h) increased cell proliferation in a cGMP-independent manner via the ERK/MAP kinase pathway. The selective inhibitor of PKG, KT5823, prevented the proliferative effect induced by NO at 24 h but not at 6 h. In conclusion, the proliferative effect of NO is initially mediated by the ERK/MAPK pathway, and at later stages by the GC/cGMP/PKG pathway. Thus, our work shows that NO induces neural stem cell proliferation by targeting these two pathways in a biphasic manner.

Dimebon enhances hippocampus-dependent learning in both appetitive and inhibitory memory tasks in mice

Pre-clinical and clinical studies on dimebon (dimebolin or latrepirdine) have demonstrated its use as a cognitive enhancer. Here, we show that dimebon administered to 3-month-old C57BL6N mice 15 min prior to training in both appetitive and inhibitory learning tasks via repeated (0.1 mg/kg) and acute (0.5 mg/kg) i.p. injections, respectively, increases memory scores. Acute treatment with dimebon was found to enhance inhibitory learning, as also shown in the step-down avoidance paradigm in 7-month-old mice. Bolus administration of dimebon did not affect the animals' locomotion, exploration or anxiety-like behaviour, with the exception of exploratory behaviour in older mice in the novel cage test. In a model of appetitive learning, a spatial version of the Y-maze, dimebon increased the rate of correct choices and decreased the latency of accessing a water reward after water deprivation, and increased the duration of drinking behaviour during training/testing procedures. Repeated treatment with dimebon did not alter the behaviours in other tests or water consumption. Acute treatment of water-deprived and non-water-deprived mice with dimebon also did not affect their water intake. Our data suggest that dimebon enhances hippocampus-dependent learning in both appetitive and inhibitory tasks in mice.

Tributyltin-induced imposex in marine gastropods involves tissue-specific modulation of the retinoid X receptor

Despite the large number of studies on the phenomenon of imposex, the mechanism underlying the abnormal growth of male sexual characters onto females in numerous gastropod species is yet to be fully elucidated. Although several hypotheses have been raised over the years, a convincing body of evidence indicates that tributyltin-induced imposex involves the abnormal modulation of the retinoid X receptor (RXR). Here, we investigate the RXR gene transcription at different timings and tissues upon exposure to environmentally relevant concentrations of tributyltin (TBT) (100 ng Sn/L TBT) in both genders of the imposex susceptible gastropod Nucella lapillus. RXR gene transcription was determined at two time-points (i.e., before and after imposex initiation) by quantitative Real Time PCR in potential target tissues: the central nervous system (CNS), penis/penis forming area (PFA), gonads and digestive gland. TBT-exposure altered transcription of RXR gene in a tissue and sex specific manner. In the CNS, a significant down-regulation was observed in females both before and after imposex initiation (P≤0.01 and P≤0.05, respectively). A similar trend was observed in male CNS at the first time-point, although differences between control and the TBT-exposed group were just above significance (P=0.059). The penis/PFA showed no differences in transcription of RXR gene between control and TBT exposed female snails before imposex induction, or before and after imposex initiation for males. However, male penis showed higher transcription of RXR gene in comparison to the PFA of females. After imposex has been induced, a significant (P≤0.001) increase in transcription of RXR gene was observed in penis of females with vas deference sequence index (VDS) levels of 3-4 in comparison with the PFA of both control and imposex females with VDS 1-2. At advanced stages of imposex, females displayed RXR transcription patterns in penis identical to those of males, which points to a functional role of RXR in the penis of both genders. In the other tissues, gonads and digestive gland, RXR gene transcription was not affected by TBT, at any of the analysed time-points. These patterns of RXR gene transcription upon TBT exposure highlight the pivotal involvement of the CNS in the mechanism of imposex induction. We integrate the results in a conceptual model, and discuss the central role of RXR and the retinoic acid signalling pathways in imposex and male genitalia formation in gastropods.

Assessment of salivary gland function in Sjögren's syndrome: the role of salivary gland scintigraphy

Salivary gland scintigraphy (SGS) is a non invasive method of salivary gland function assessment. This technique is easy to perform, reproducible and well tolerated by patients. Additionally, an abnormal salivary gland scintigraphy result is accepted by the American-European consensus group as a criterion for the diagnosis of Sjögren's syndrome. Scintigraphic evaluation of salivary gland function also plays an important role in therapeutic decision and patient follow-up. Schall's categorical classification is usually considered the standard method for salivary scintigraphy interpretation, though subjective and with limited capacity to discriminate borderline results. In order to improve the diagnostic accuracy of SGS, there has been an increasing interest in the quantification of glandular function. However, the debate on the most reliable and suitable parameters for the diagnosis of SS persists.

Clear-PEM: a dedicated PET camera for improved breast cancer detection

Positron emission mammography (PEM) can offer a non-invasive method for the diagnosis of breast cancer. Metabolic images from PEM using 18F-fluoro-deoxy-glucose, contain unique information not available from conventional morphologic imaging techniques like X-ray radiography. In this work, the concept of Clear-PEM, the system presently developed in the frame of the Crystal Clear Collaboration at CERN, is described. Clear-PEM will be a dedicated scanner, offering better perspectives in terms of position resolution and detection sensitivity.

Sodium channel currents in maturing acutely isolated rat hippocampal CA1 neurones

Sodium channel currents were recorded in excised inside-out patches from immature (P(4-10)) and older (P(20-46)) rat CA1 neurones. Channel conductance was 16.6+/-0.013 pS (P(20-46)) and 19.0+/-0.031 pS (P(4-10)). Opening patterns varied with step voltage and with age. In some patches bursting was apparent at voltages positive to -30 mV. Non-bursting behaviour was more dominant in patches from younger animals. In older animals mean open time (m.o.t.) was best described by two exponentials especially in the older cells; in the immature, there were fewer cases with two exponentials. The time constant of inactivation (tau(h)) estimated in ensemble averages was best described by two exponentials (tau(hf) and tau(hs)) in most patches from older cells. tau(hf) decreased with depolarization; tau(hs) increased in the range -30 to 0 mV. The voltage dependence of tau(hf) in the older cells is identical to that of the single tau(h) found in the younger; the results indicate a dominance of tau(hf) in the younger. Patches from younger cells more often showed one apparent active channel; in such cases, m.o.t. was described by a single exponential. However, in two cases, channels showed bursting behaviour with one of these channels showing a shift between bursting and non-bursting modes. Our findings are consistent with a heterogeneous channel population and with changes in the population in the course of maturation.

Molecular genetic analysis of factor XI deficiency: identification of five novel gene alterations and the origin of type II mutation in Portuguese families

Coagulation factor XI (FXI) deficiency is an inherited autosomal recessive mild bleeding disorder. In this study, we report the molecular genetic analysis of FXI deficiency in six unrelated families of Portuguese origin. The Jewish type II mutation was found in two families, of seemingly Portuguese origin. Haplotype analysis in these families demonstrated that this mutation is of Jewish origin. In the remaining families, five novel FXI mutations have been identified. Two of these mutations (FXI IVS K -10T-->A and FXI 1026G-->T, cd 324) affect the FXI pre-mRNA splicing. A further two (FXI 307 ins AAGCAAT, cd 85 and FXI 1072 del A, cd 340) introduce frameshifts leading to premature termination codons. The FXI splicing mutation, 1026G-->T cd 324, was found in compound heterozygosity with missense mutation FXI K518N. Analysis of the FXI mRNA from the latter genotype demonstrated new donor splice site usage. All reported mutations most likely result in functional null-alleles. In addition, three novel polymorphisms have been identified: at nt -138 in intron A, at codon D125 in exon 5 and at codon T249 in exon 8.

Multiple endocrine neoplasia type 2A. Study of a family

INTRODUCTION

Pheochromocytomas (Pheo) can occur sporadically, isolated or in association with other neuroendocrine lesions. In multiple endocrine neoplasia type 2A (MEN-2A), Pheo is associated to medullary thyroid carcinoma (MTC) or its precursor, C-cell hyperplasia (CCH) and parathyroid hyperplasia. Genetic screening provides early diagnosis and preventive treatment. In order to validate DNA analysis as a reliable method of early identification of gene carriers, we compared the results of genetic screening with clinical, biochemical, imaging and pathological findings in the members of an affected family.

POPULATION AND METHODS

The diagnosis of a bilateral necrotic Pheo in a female patient led to the study of a family with four generations, aged 3 to 78 years (mean = 30.3 yrs). The study included a clinical examination; basal and pentagastrin stimulated calcitonin values; urinary catecholamines and their metabolites; serum calcium and a genetic study (direct sequence of PCR products from genomic DNA isolated from leucocytes using specific primers in exon 11 of the RET protooncogene of chromosome 10). The radiologic study, gammagraphic study (131I-MIBG) and magnetic resonance study were performed in members with clinical suspicion of Pheo.

RESULTS

Seven out of nine patients had a mutation on codon 634 of exon 11 of RET (TGC-CGC), leading to cysteine arginine substitution in the codified protein; all gene carriers had biochemical markers of MTC/CCH and four of Pheo. The Pheo patients underwent adrenalectomy (bilateral in three) and all the gene carriers underwent prophylactic thyroidectomy. The pathologic findings were: MTC in four (metastasized in one); CCH in three and parathyroid hyperplasia in one.

CONCLUSIONS

Phenotypic penetration of RET mutation was 100% for MTC/CCH, but only 57% of the gene carriers had Pheo. Genetic screening allowed early prophylactic treatment in four out of seven patients; pathologic findings revealed several evolutionary stages of the disease. Patients not yet showing Pheo are under close clinical and laboratory surveillance.

Sustained potassium currents in maturing CA1 hippocampal neurones

Whole-cell voltage clamp techniques were used to characterize sustained outward currents in maturing (P4 to P48) acutely isolated rat CA1 hippocampal neurones. Sodium removal and signal subtraction were used to isolate a sodium dependent sustained potassium current (IKNa). Calcium blockade (Co2+), sensitivity to a low TEA dose (0.5 mM) and sensitivity to Charibdotoxin (CTX 25 nM) and Iberiotoxin (IbTX 25 nM), in conjunction with signal subtraction, were used to isolate a sustained current with the characteristics of IC (IKCa). IKNa was found in both immature (P4-5) and older (P > 21) cells; this corresponded, respectively, to 56 +/- 5% and 36 +/- 6% of the outward current in younger and older cells. In the course of maturation, the voltage dependence of activation of IKNa shifted to more hyperpolarized values by approximately 20 mV. In the younger cells (P5-18) there was no evidence for sensitivity to CTX or IbTX. In 55 out of 77 older cells we found a component sensitive to CTX, IbTX, 0.5 mM TEA and Co2+.

Technetium-99m labelling of the IOR CEA 1 monoclonal antibody: evaluation of different methods

AIM

The aim of this study was to investigate the in vivo and in vitro properties of 99mTc labelled monoclonal antibody, IOR CEA 1 when radiolabelled by different methods.

METHODS

To achieve that purpose IOR CEA was directly radiolabelled via 2-mercaptoethanol (2-Me) and stannous ion (SnCl2) reduction and indirectly via the 2-iminothiolane (2-Im) conjugation. The resulting 99mTc-MoAbs were analysed for number of free sulfhydryl groups, chemical and radiochemical purity (checked by HPLC and SDS PAGE), immunoreactivity and biological distribution in mice.

RESULTS

Experimental results indicated a similar radiochemical purity and immunoreactivity for direct labelling methods and a decrease of both for 2-Im method. 2-Me antibody reduction led to a high antibody fragmentation as indicated by non-denaturing SDS PAGE analysis. Nevertheless SnCl2 and 2-Im labels revealed lower in vivo stability.

CONCLUSION

99mTc-(2-Me) IOR CEA presented favorable in vitro and in vivo properties. Therefore this label was compared to 99mTc-monoclonal antibody BW 431/26. Similar characteristics were found. Clinical studies also revealed identical biodistribution profile.

[Anti-melanoma immunoscintigraphy]

Nuclear Medicine has always contributed to the study of oncologic diseases. Immunoscintigraphy, one of its more recent developments, consists of the evaluation of the biodistribution of antibodies, directed against tumoral antigens and labelled with radionuclides. This technique, which has proven of special interest in some neoplasias, was used for the first time in 1983 in malignant melanoma of the skin. The antibody that has been more frequently used and which is used in the Instituto de Medicina Nuclear (IMN) of the Faculdade de Medicina de Lisboa, is antibody 225.28S, an IgG2a directed against a high molecular weight antigen present in the melanoma cell. In the IMN, we started immunoscintigraphy anti-melanoma in February 1992. During these two years, we have performed 67 exams, 44 on patients with malignant melanoma of the skin and 23 on uveal melanoma. We have obtained true positive rates and true negative ones, respectively, of 87.5% and 90% in melanoma of the skin, and 94% and 83% in uveal melanoma. It has been shown that the main clinical contribution of immunoscintigraphy for malignant melanoma of the skin is the study of loco-regional and distant metastases, namely those clinically unsuspected, as well as in the differential diagnosis of a lesion already known. In uveal melanoma, it is accepted that immunoscintigraphy may be useful in the evaluation of the primary lesion, namely in the differential diagnosis with other intra-ocular lesions.

Potassium currents in acutely isolated maturing rat hippocampal CA1 neurones

Whole-cell voltage clamp techniques were used to characterize the postnatal development of current amplitude and inactivation and activation kinetics of two potassium currents in acutely isolated CA1 cells from rats P4 to P52: the A-current (IA) and a slow-rising, slow inactivating current (IK). In the course of maturation, changes in the relative proportion of IA and IK currents were observed, the latter becoming a dominant current in older cells. The half-maximal point (Vh) of steady-state inactivation and activation of IA and IK shifted in the course of the first and second postnatal weeks. The shifts were hyperpolarizing in the case of IK, whereas IA shifted to less negative values. The shifts in steady-state inactivation Vh were accompanied by a change in the slope factor (Vs), which is an indication of a modification in the voltage sensitivity of the steady-state inactivation. The kinetics of IK evolve after birth in a fashion that matches the changes in action potential parameters previously reported.

Yeast exo-beta-glucanases can be used as efficient and readily detectable reporter genes in Saccharomyces cerevisiae

Yeast exo-1,3-beta-glucanases are secretable proteins whose function is basically trophic and may also be involved in cell wall glucan hydrolytic processes. Since fluorescein di(beta-D-glucopyranoside) is a fluorogenic substrate detectable and quantifiable by flow cytometry, it was used for testing the ability of the EXG1 gene product of Saccharomyces cerevisiae and its homologous gene in Candida albicans to function as reporter genes. These open reading frames were coupled to different promoters in multicopy plasmids, and exoglucanase activity quantified at flow cytometry. Exoglucanases were found to be useful tools for the study of promoter regions in S. cerevisiae. This technique has the advantage over other reporter gene systems--such as beta-galactosidase fusions--that it does not require permeabilization of yeast cells and therefore it allows the recovery of viable cells--by sorting--after flow cytometry analysis.

Slow and medium afterhyperpolarizations in maturing rat hippocampal CA1 neurones

The postnatal evolution of the signals underlying the afterhyperpolarization (slow-AHP and medium-AHP) was studied in rat CA1 hippocampal neurones (P10-16, P17-23 and P greater than 26) using in vitro slices. Noradrenaline (NA) and signal subtraction were used to decompose the AHP (m-AHP and s-AHP). The amplitude of the s-AHP was found significant between P10-16 and P17-23 cells; the m-AHP showed no significant change. The time to peak of the s-AHP of the P greater than 26 cells was found to be significantly different from the remaining groups; the m-AHP showed no significant change. The changes in waveform and amplitude of the AHP at this stage were found to be mainly due to the modifications of the slow-AHP.

Choledochoenterostomy with an anti-reflux mechanism

A new technique of choledochoenterostomy was devised to solve some of the problems of enterobiliary anastomosis with a normal calibre. The distal extremity of the common bile duct is completely surrounded by the bowel mucosa to a length of 3 cm after seromyectomy of a bowel wall rectangle of 4 x 1 cm. Experimental studies in rats and dogs demonstrated that this procedure prevents the risks of anastomotic disruption and functions like a mechanical unidirectional valve, which has great efficacy in stopping enterobiliary reflux. Studies in ten patients with obstructive jaundice with an extrahepatic biliary dilation less than 1.2 cm diameter submitted to this procedure confirmed the experimental results. All patients were asymptomatic, without jaundice and with normalization of the liver enzymes after 2 months. The permeability of the valvular anastomosis studied by cholangiography, the HIDA 99mTc test and manometry was quite similar to other classical biliary-enteric anastomosis. In contrast, anti-reflux efficacy was only demonstrated in patients with a valvular anastomosis.

Afterpotential characteristics and firing patterns in maturing rat hippocampal CA1 neurones in in vitro slices

The postnatal evolution of depolarizing after-potentials (DAPs) and after-hyperpolarizations (AHPs) was studied in rat CA1 hippocampal neurones (5-68 days of age) using in vitro slices. Results were pooled into 4 age groups: P5-9, P10-16, P17-24 and P26-68. In P5-9 cells, DAPs were seen as passive signals, with a time constant similar to the time constant of the membrane. The evolution of the DAP was characterized by a decrease in amplitude, an increase in duration and a change in contour. In P10-16 and P17-24 cells, the DAPs often had a plateau or a hump-like shape which increased the probability of firing and the occurrence of spike doublets. The firing pattern and bursting behaviour of P10-16 CA1 neurones differed from the pattern typical of the adult. P5-9 and P10-16 cells had post-burst AHPs with a smaller amplitude and a more prolonged early phase than at late stages of development.