The urgency for a change in genetics healthcare provision: views from Portuguese medical geneticists

In the last decades, genetics has experienced significant technological advancements worldwide. However, in Portugal, serious limitations persist, compromising the functioning of healthcare in medical genetics. This study aimed to promote sharing and discussion among genetic medical professionals, to outline concrete actions to address gaps in clinical practice. Three focus groups were conducted with 19 specialists in medical genetics. The data were analyzed using the thematic analysis method to extract the main themes from the discussions. From the analysis, four conceptual themes emerged: (i) framing Portuguese genetic services in light of the European context; (ii) improvement of medical genetics education and population literacy; (iii) transforming of medical genetics services; and (iv) operationalizing the change. The results demonstrated that increasing training resources and strengthening multiprofessional teams by hiring more genetic professionals, such as clinical geneticists, molecular geneticists, and other genetic specialists, is crucial to enhancing the responsiveness of genetic services. Integrating medical genetics into all specialties and primary care, as well as updating the national network of medical genetics, are critical points for increasing equity and enabling healthcare to be provided more fairly. Including other medical genetics professionals such as genetic counsellors, nurses and psychologists also plays a significant role in providing comprehensive and quality care. This collaborative approach aims to provide effective genetic assistance and enhance the adequacy of genetic healthcare. The findings are compiled as recommendations to support the profession moving forward that can be applied to other healthcare contexts worldwide.

Genetic counselling supervision: Luxury or necessity? A qualitative study with genetic healthcare professionals in Portugal

In recent years, there has been a significant technological evolution in the field of genetics, leading to an increase in the number of professionals working in medical genetics and, consequently, a tremendous growth in genetic counselling. At the same time, there has been a growing recognition of the parameters on which to base a safe practice, not only regarding the technical skills of the professional but also regarding their counselling skills, including relational and empathy skills and the acknowledgement of the emotional impact that genetic counselling practice can have. However, despite this growing knowledge, there are still significant differences between the various European countries, and one area where this discrepancy is particularly evident is genetic counselling supervision. Thus, if there are countries where genetic counselling supervision is not even known by the professionals, there are others where it is mandatory for practice. This research had as an objective to understand if and how genetic counselling supervision is provided in Portugal, to identify routines, challenges and impacts of genetic counselling that should be explored in a supervision process and comprehend how professionals believe supervision should be conducted to be effective. A total of sixteen medical geneticists from main Portuguese genetic services were present in two online focus groups. None of the participants had access to genetic counselling supervision as a programmed routine and there was a consensus that a service of this kind would be particularly important for the professionals as genetic counselling has frequently challenging and emotional moments. Aspects regarding clinical supervision, the characteristics of the supervisor and the practical aspects of genetic counselling supervision implementation were also mentioned during the discussions. These results highlight the relevancy of the establishment of GC supervision routines and standardized guidelines in our country, as well as a need for evidence-based research focused on its impact at professional and practice level.

Carbamazepine, venlafaxine, tramadol, and their main metabolites: Toxicological effects on zebrafish embryos and larvae

Pharmaceutical compounds and their metabolites are found in natural and wastewater. However, investigation of their toxic effects on aquatic animals has been neglected, especially for metabolites. This work investigated the effects of the main metabolites of carbamazepine, venlafaxine and tramadol. Zebrafish embryos were exposed (0.1-100 µg/L) for 168hpf exposures to each metabolite (carbamazepine-10,11-epoxide, 10,11-dihydrocarbamazepine, O-desmethylvenlafaxine, N-desmethylvenlafaxine, O-desmethyltramadol, N-desmethyltramadol) or the parental compound. A concentration-response relationship was found for the effects of some embryonic malformations. Carbamazepine-10,11-epoxide, O-desmethylvenlafaxine and tramadol elicited the highest malformation rates. All compounds significantly decreased larvae responses on a sensorimotor assay compared to controls. Altered expression was found for most of the 32 tested genes. In particular, abcc1, abcc2, abcg2a, nrf2, pparg and raraa were found to be affected by all three drug groups. For each group, the modelled expression patterns showed differences in expression between parental compounds and metabolites. Potential biomarkers of exposure were identified for the venlafaxine and carbamazepine groups. These results are worrying, indicating that such contamination in aquatic systems may put natural populations at significant risk. Furthermore, metabolites represent a real risk that needs more scrutinising by the scientific community.

An European overview of genetic counselling supervision provision

Genetic testing is becoming more commonplace in general and specialist health care, and should always be accompanied by genetic counselling, according to legislation in many European countries and recommendations by professional bodies. Personal and professional competence is necessary to provide safe and effective genetic counselling. Clinical and counselling supervision of genetics healthcare practitioners plays a key role in quality assurance, providing a safe environment not only for patients but for professionals too. However, in many European countries, genetic counsellors are still an emerging professional group and counselling supervision is not routinely offered and there are no enough evidences on the impact of these insufficiencies. This study aimed to explore the current status of genetic counselling supervision provision across Europe and to ascertain factors that might be relevant for the successful implementation of counselling supervision. A total of 100 practitioners responded to an online survey; respondents were from 18 countries, with the majority working in France (27%) and Spain (17%). Only 34 participants reported having access to genetic counselling supervision. Country of origin, the existence of a regulation system and years of experience were factors identified as relevant, influencing access and characteristics of counselling supervision. Although there is a growing number of genetic counsellors trained at European level, just a few countries have implemented and required as mandatory the access to genetic counselling supervision. Nevertheless, this is essential to ensure a safe and effective genetic counselling and should be regulated at the European genetic healthcare services.

Milk yield and composition in dairy cows with post-partum disorders

ABSTRACT This study aimed to determine the impact of different post-partum disorders on milk yield and composition. One hundred and fifteen Holstein cows from a commercial dairy farm located in the state of Rio Grande do Sul in southern Brazil were monitored up to 62 days post-partum. During this period, body condition score evaluation and animal clinical examination were conducted. Percentages of fat, protein, and lactose, as well as somatic cells score, were determined in milk samples. The AST activity and concentrations of NEFA, calcium, and BHBA, were analyzed in blood samples. The occurrence of clinical disorders was identified in 30 (26%) cows. Subclinical disorders were identified in 64 (56%) cows. Only 21 (18%) cows did not suffer any kind of disorder within the studied period. In this study, no significant differences were found in milk production, protein, and somatic cell count in clinical, subclinical, and healthy cows. Milk fat and the fat: protein quotient (F:P) were higher in cows with clinical disorders and the 6 to 21 days in milk, and lactose were lower in cows with clinical disorders and the 22 to 42 days in milk (P<0.05).

Norfluoxetine and venlafaxine in zebrafish larvae: Single and combined toxicity of two pharmaceutical products relevant for risk assessment

Antidepressant metabolites are found in natural and waste waters. However, investigation of their toxic effects on aquatic animals, single or in mixture with other occurring psychoactive drugs, has been neglected. Here, effects of 80hpf exposure to norfluoxetine (0.64-400 ng/L), venlafaxine (16-10000 ng/L) or their combination (3.2 ng/L +2000 ng/L, respectively) were investigated in embryos and zebrafish larvae. Mortality, embryonic malformations, sensorymotor reflexes and the expression of 34 genes involved in the toxicants mode-of-action (MoA) and metabolism were evaluated (i.e. monoamine receptors and transporters, nuclear receptors, and detoxification transporters and enzymes). Compared to controls, norfluoxetine treatments only caused depigmentation of embryos and larvae. Venlafaxine-exposed larvae exhibited depigmentation and spinal deformities, impaired sensorymotor reflexes, alterations in the expression of genes belonging to the serotonergic, noradrenergic and dopaminergic pathways, as well as nuclear receptors related to lipid and drug metabolism. The mixture elicited distinct interaction effects, depending on the level of biological organisation analysed and the neurotransmitter pathways affected; synergism (lethality), no interaction (sensorymotor reflexes), antagonism and inverse agonism (gene expression). The results call for investigation of the toxicity of pharmaceutical metabolites single and in mixture, as well as their risk assessment in approaches accounting for possible interactions with other endocrine-disrupting compounds.

Comparison of peribulbar block and general anaesthesia in mechanical vitrectomy: a prospective observational study

INTRODUCTION

Vitrectomy surgery is a common procedure for the treatment of several types of ophthalmologic conditions. It can be performed under regional anaesthesia with peribulbar block (PB) or general anaesthesia (GA). There are no evidence-based recommendations on the optimal anaesthesia strategy for this procedure. The aim of this study was to compare the advantages of PB and GA for vitrectomy surgery.

MATERIALS AND METHODS

A prospective observational study was conducted on adults submitted for mechanical vitrectomy between January 2017 and December 2017. Demographic and perioperative data were collected, namely ASA physical status, median arterial pressure, heart rate, postoperative opioid consumption, postoperative nausea and vomiting, times of induction, surgery, recovery, and hospital stay and costs considering medication and material needed. Statistical analysis was performed using SPSS v.25, with chi-square, Fisher and Mann-Whitney U tests, according to the type of variables analysed.

RESULTS AND DISCUSSION

We included 179 patients submitted for mechanical vitrectomy: 91 (51%) with PB and 88 (49%) under GA. Patients submitted to PB were older (69.0 vs. 64.5 years, p=.006) and presented with higher ASA physical status (p=.001). For haemodynamic outcomes, patients submitted to PB presented with less variation of median arterial pressure (-3.0 vs. -13.5mmHg, p=.000) and with no significant differences in heart rate (-2.0 vs. -3.0 bpm, p=.825). In the postoperative period, the PB group presented with decreased need of postoperative analgesia (0.0 vs. 5.0, p=.026) and a lower incidence of nausea and vomiting (1.0 vs. 12.0, p=.001). Times related to anaesthesia and surgery were better in PB group, with shorter induction time (10.0 vs. 11.0min, p=.000), surgery time (56.5 vs. 62.0min, p=.001), recovery time (10.0 vs. 75.5min, p=.000), and hospital stay (2.0 vs. 3.0 days, p=.000). When analysing costs, PB was less expensive than GA (4.65 vs. 12.09 euros, p=.021) CONCLUSION: PB is a reliable and safe alternative to GA for patients undergoing mechanical vitrectomy, permitting good anaesthesia and akinesia conditions during surgery, better haemodynamic stability, and less postoperative complications, especially in older patients and those with more comorbidities.

The last frontier: Coupling technological developments with scientific challenges to improve hazard assessment of deep-sea mining

The growing economic interest in the exploitation of mineral resources on deep-ocean beds, including those in the vicinity of sensitive-rich habitats such as hydrothermal vents, raise a mounting concern about the damage that such actions might originate to these poorly-know ecosystems, which represent millions of years of evolution and adaptations to extreme environmental conditions. It has been suggested that mining may cause a major impact on vent ecosystems and other deep-sea areas. Yet, the scale and the nature of such impacts are unknown at present. Hence, building upon currently available scientific information it is crucial to develop new cost-effective technologies embedded into rigorous operating frameworks. The forward-thinking provided here will assist in the development of new technologies and tools to address the major challenges associated with deep sea-mining; technologies for in situ and ex situ observation and data acquisition, biogeochemical processes, hazard assessment of deep-sea mining to marine organisms and development of modeling tools in support of risk assessment scenarios. These technological developments are vital to validate a responsible and sustainable exploitation of the deep-sea mineral resources, based on the precautionary principle.

Linking cortisol response with gene expression in fish exposed to gold nanoparticles

Fish exposure to environmental stressors (e.g. chemicals, hypoxia, temperature) induce responses enabling them to cope with alterations in their environment. A stress response involves a wide array of changes, from molecular to physiological and behavioural, set to counteract the effect of the stressor and recover homeostatic equilibrium. Among other processes, there is activation of the hypothalamus-pituitary-interrenal (HPI) axis, resulting in stimulation of the steroidogenic pathway and release of cortisol, important mediator of the adaptive response to stress. The purpose of this study was to evaluate if exposure of a marine teleost (gilthead sea bream) to gold nanoparticles (AuNP) could interfere with the HPI axis eliciting an acute stress response and how this response would be linked with alterations in the mRNA levels of target genes in the head kidney, important centre of endocrine response in fish. Fish were exposed via water, for 96h, to four concentrations (0, as control, 4, 80 and 1600μg⋅L^-1) of 40nm spherical AuNP, covered with two different types of coatings (citrate and PVP). At the end of the exposure, fish were anesthetized and blood and the head kidney sampled. Results showed that exposure to 1600μg⋅L^-1 AuNP-citrate and 80μg⋅L^-1 AuNP-PVP increased plasma cortisol levels, compared to controls, but caused no change in glucose levels. AuNP modulated the expression of target genes related to oxidative stress, cell-tissue repair, immune function and apoptosis in the head kidney of fish. The patterns of response were distinct for the two coatings tested. Unlike AuNP-citrate, AuNP-PVP elicited an inverted U-shaped response. Present findings demonstrated that AuNP were able to activate the fish HPI axis and alter a battery of related molecular markers in the head kidney.

The use of biomarkers as integrative tools for transitional water bodies monitoring in the Water Framework Directive context - A holistic approach in Minho river transitional waters

The Water Framework Directive (WFD) provides an important legislative opportunity to promote and implement an integrated approach for the protection of inland surface waters, transitional waters, coastal waters and groundwaters. The transitional waters constitute a central piece as they are usually under high environmental pressure and by their inherent characteristics present monitoring challenges. Integrating water quality monitoring with biological monitoring can increase the cost-effectiveness of monitoring efforts. One way of doing this is with biomarkers, which effectively integrate physical-chemical status and biological quality elements, dealing holistically with adverse consequences on the health of water bodies. The new Marine Strategy Framework Directive (MSFD) already incorporates the biomarker approach. Given the recent activities of OSPAR and HELCOM to harmonize existing monitoring guidelines between MSFD and WFD the use of similar methodologies should be fostered. To illustrate the potential of the biomarker approach, juveniles of flounder (Platichthys flesus) were used to evaluate the quality of the Minho river-estuary water bodies. The use of juveniles instead of adults eliminates several confounding factors such changes on the biological responses associated with reproduction. Here, a panel of well-established biomarkers, EROD, AChE, SOD, CAT, GST, LPO, ENA and FACs (1-Hydroxyrene) were selected and measured along with a gradient of different physical conditions, and integrated with trace elements characterization on both biota and sediments. In general, a clear profile along the water bodies was found, with low seasonal and spatial variation, consistent with a low impacted area. Overall, the results support the use of both the battery of biomarkers and the use of juvenile flounders in the monitoring of the water quality status within the WFD.

Genetics Health Professionals' Views on Quality of Genetic Counseling Service Provision for Presymptomatic Testing in Late-Onset Neurological Diseases in Portugal: Core Components, Specific Challenges and the Need for Assessment Tools

Quality assessment of genetic counseling practice for improving healthcare is a challenge for genetic services worldwide; however, there is scarce literature regarding quality issues in genetic counseling in the context of presymptomatic testing for late-onset neurological diseases (Paneque et al. 2012) The aims of this qualitative study were to: (1) explore the views of professionals' who provide genetic counseling services for presymptomatic testing for late-onset neurological diseases regarding relevant quality indicators for counseling practice; and (2) examine current assessment of such counseling practice for Portuguese genetic services. Quality indicators are a means of measuring either the process or outcomes of patient services, with the aim of evaluating and improving quality of care (Mainz 2003). In this study, we defined quality indicators as measurable outcomes of the counseling process that may reflect good professional practice and desirable end-term effects. We undertook interviews with 18 genetic health professionals (85 % of all genetic counseling professionals involved) from the major genetic services in Portugal. Results indicate that professionals valued some core components of genetic counseling, including providing information and decision-making support, informing the consultand about the genetic counseling protocol, as well as exploring motivations, expectations for test results, consequent anticipated life changes, psychosocial adjustment, and personal and familial experience with the disease. Professionals were not, however, able to clearly elucidate quality indicators for effective practice and some reported they had not reflected on that topic before. Professionals also reported specific challenges in their practice, such as ambiguity of the health/illness status and affirming consultands' autonomy. Results of the study have revealed a lack of knowledge about quality indicators and tools to assess counseling practice. A credible set of quality indicators for presymptomatic testing is required as a foundation for the development of specific tools.

Involvement of the antioxidant system in differential sensitivity of Carcinus maenas to fenitrothion exposure

Carcinus maenas is an invertebrate with worldwide distribution and high ability to adapt to different environments, which is frequently used in environmental monitoring. Despite this, it is not clear how historical exposure to moderate contamination may influence sensitivity to further chemical stress in this important decapod species. This study investigated differential responses to organophosphate fenitrothion of C. maenas from a moderately contaminated estuary and a low impacted one, using in vitro and in vivo biomarker assays. To clarify potential differences in sensitivity, a biochemical characterisation of muscle cholinesterases was first performed. The results indicated acetylcholinesterase (AChE) as the main form present in C. maenas muscle. Exposure assays revealed that crabs from the moderately contaminated site were less sensitive to fenitrothion showing lower AChE inhibition than those from the low impacted site. Other biomarker changes detected in these animals were: increased anaerobic metabolism (muscle lactate dehydrogenase), enhanced phase II biotransformation (glutathione S-transferases in the digestive gland) and antioxidant defences (i.e., activities of glutathione reductase, glutathione peroxidase and catalase, and levels of total glutathiones in the digestive gland). Altogether, the results pointed out a role for the glutathione redox system towards tolerance to fenitrothion exposure.

Exposure of Carcinus maenas to waterborne fluoranthene: accumulation and multibiomarker responses

Fluoranthene (FLU) is a priority polycyclic aromatic hydrocarbon (PAH) commonly detected in estuarine sediments, water and biota. Despite this, information on FLU detection, accumulation and effects on marine crustaceans is scarce. This work investigated the accumulation of FLU in Carcinus maenas and the responses of several early-warning biomarkers after a 7-day laboratory exposure to five FLU concentrations (2.56 to 100 μg L(-1)). After exposure to FLU, sub-samples of the crabs' digestive gland and muscle were collected for biomarker determinations. The remaining digestive gland and muscle, together with the rest of the whole-body soft tissues, were analysed for FLU residues by gas chromatography-mass spectrometry (GC-MS). The biomarkers assessed were: i) the quantification of FLU-type compounds by fixed wavelength fluorescence (FF); ii) the activities of glutathione S-transferases (GST) and glutathione reductase (GR), and the levels of total glutathione (GT) and lipid peroxidation (LPO) for oxidative stress; iii) the activity of acetylcholinesterase (AChE) for neurotoxicity; iv) the activities of isocitrate dehydrogenase (IDH) and lactate dehydrogenase (LDH) enzymes, and total protein, glycogen and lipids as indicators of changes in energy metabolism and storage; and v) the lysosomal membrane stability (LMS) as a measure of cell damage. The results showed strong (R(2)>0.95) concentration-dependent accumulation of FLU residues (as measured by GC-MS) in the remaining whole-body soft tissues and of FLU-type compounds (as measured by FF) in the digestive gland and muscle. A strong positive linear relationship (R(2)=0.91) between FLU residues and FLU-type compounds was also found. Comparing to controls, activities of GST and GR were significantly higher in crabs exposed to ≥16 and ≥40 μg L(-1) FLU, respectively. TG levels and IDH activity showed a significant trend to increase with FLU concentrations whereas AChE activity exhibited the opposite trend. FF measurements in the digestive gland and muscle proved to be an expeditious cost-effective method to assess the uptake and availability of FLU and its metabolites in C. maenas. The results suggest that under continuous environmental exposure, FLU may enhance detoxification and anti-oxidant defences, and cause alterations in the aerobic energy pathway, as well as neuromuscular toxic effects that may increase C. maenas risk of predation.

What counts as effective genetic counselling for presymptomatic testing in late-onset disorders? A study of the consultand's perspective

Genetic counselling must be offered in the context of presymptomatic testing (PST) for severe late-onset diseases; however, effective genetic counselling is not well defined, and measurement tools that allow a systematic evaluation of genetic practice are still not available. The aims of this qualitative study were to (1) recognize relevant aspects across the whole process of genetic counselling in PST for late-onset neurodegenerative disorders that might indicate effective practice from the consultand's perspective; and (2) analyse aspects of current protocols of counselling that might be relevant for successful practice. We interviewed 22 consultands undergoing PST for late-onset neurological disorders (Huntington disease, spinocerebellar ataxias and familial amyloid polyneuropathy ATTRV30M) in the three major counselling services for these diseases in Portugal. The main themes emerging from the content analysis were (1) the consultand's general assessment of the PST process in genetic services; (2) appropriateness and adaptation of the protocol to the consultand's personal expectations and needs; and (3) consultand's experience of the decision-making process and the role of engagement and counselling skills of the counsellor. Participants also provided a set of recommendations and constructive criticisms relating to the length of the protocol, the time gap between consultations and the way results were delivered. These issues and the construction of the relationship between counsellor and counselee should be further investigated and used for the improvement of current protocols of counselling.

Zonation of Ciliated Cells on the Epithelium of the Rat Trachea

We have used scanning electron microscopy (SEM) to screen the entire epithelial surface of the cervical trachea of the adult rat. This scrutiny revealed that the density of ciliated cells along this epithelium follows a repetitive pattern: circular strips of high density of ciliated cells alternate with areas of low density of the same cells. Cilia-poor strips of the tracheal epithelium were seen on areas of cartilage rings; here, ciliated cells made up 32% of the total surface of the tracheal lining. Cilia-rich areas filled the epithelial surface at the tracheal ligaments (i.e., the regions located in-between the rings); here, ciliated cells occupied 65% of the tracheal lumen. In the cilia-poor zones, the density of ciliated cells decreased from its periphery into its center, where cilia were virtually absent. No differences in this pattern of the tracheal epithelium were seen between young adult and older rats. We conclude that the respiratory epithelium expresses density zonation of ciliated cells on the trachea of adult rats. We propose that the high concentration of ciliated cells on the regions of epithelium located at the tracheal ligaments suggests that these zones are electively committed in the clearance of the respiratory airway.

Trinucleotide repeats in 202 families with ataxia: a small expanded (CAG)n allele at the SCA17 locus

BACKGROUND

Ten neurodegenerative disorders characterized by spinocerebellar ataxia (SCA) are known to be caused by trinucleotide repeat (TNR) expansions. However, in some instances the molecular diagnosis is considered indeterminate because of the overlap between normal and affected allele ranges. In addition, the mechanism that generates expanded alleles is not completely understood.

OBJECTIVE

To examine the clinical and molecular characteristics of a large group of Portuguese and Brazilian families with ataxia to improve knowledge of the molecular diagnosis of SCA.

PATIENTS AND METHODS

We have (1) assessed repeat sizes at all known TNR loci implicated in SCA; (2) determined frequency distributions of normal alleles and expansions; and (3) looked at genotype-phenotype correlations in 202 unrelated Portuguese and Brazilian patients with SCA. Molecular analysis of TNR expansions was performed using polymerase chain reaction amplification.

RESULTS

Patients from 110 unrelated families with SCA showed TNR expansions at 1 of the loci studied. Dominantly transmitted cases had (CAG)(n) expansions at the Machado-Joseph disease gene (MJD1) (63%), at SCA2 (3%), the gene for dentatorubropallidoluysian atrophy (DRPLA) (2%), SCA6 (1%), or SCA7 (1%) loci, or (CTG)(n) expansions at the SCA8 (2%) gene, whereas (GAA)(n) expansions in the Freidreich ataxia gene (FRDA) were found in 64% of families with recessive ataxia. Isolated patients also had TNR expansions at the MJD1 (6%), SCA8 (6%), or FRDA (8%) genes; in addition, an expanded allele at the TATA-binding protein gene (TBP), with 43 CAGs, was present in a patient with ataxia and mental deterioration. Associations between frequencies of SCA2 and SCA6 and a frequency of large normal alleles were found in Portuguese and Brazilian individuals, respectively. Interestingly, no association between the frequencies of DRPLA and large normal alleles was found in the Portuguese group.

CONCLUSIONS

Our results show that (1) a significant number of isolated cases of ataxia are due to TNR expansions; (2) expanded DRPLA alleles in Portuguese families may have evolved from an ancestral haplotype; and (3) small (CAG)(n) expansions at the TBP gene may cause SCA17.

Encapsulated anaplastic thyroid carcinoma with three-year disease-free survival

This is a report of an unusual anaplastic thyroid carcinoma case with capsule and long disease-free survival. This 74-year-old male, with an asymptomatic nodule in the mid-line neck for 5 years, was treated with total thyroidectomy. Light microscopy and immunohistochemistry showed an anaplastic carcinoma of the thyroid isthmus. There were no signs of carcinoma elsewhere either at the time of surgery or 35 months later, when the patient was last seen.

Genetic and developmental models for the neural control of breathing in vertebrates

The present paper reviews some of the possible mechanisms that may link gene function in the brainstem and breathing patterns in vertebrates. On one hand, adaptation and acclimatisation of mature breathing to environmental constraints such as hypoxia, involves complex regulation of the gene expression in precise cardiorespiratory sites of the brainstem. On the other hand, targeted inactivation of different genes suggests that postnatal respiratory variables at rest depend on genes controlling the prenatal development of the brainstem. During embryogenesis, neurotrophins (gdnf, bdnf) regulate the survival of specific cellular populations composing the respiratory neuronal network. The expression of developmental genes such as Hox and Krox-20 initiates hindbrain segmentation, the earliest sign of regionalisation in the brainstem. As shown in the chick embryo, segmental specifications allow the establishment of an active embryonic rhythmic network and later insertion of specific neuronal circuits increasing the primordial rhythm frequency to near mature values.

High germinal instability of the (CTG)n at the SCA8 locus of both expanded and normal alleles

The autosomal dominant spinocerebellar ataxias (SCAs) are a group of late-onset, neurodegenerative disorders for which 10 loci have been mapped (SCA1, SCA2, SCA4-SCA8, SCA10, MJD, and DRPLA). The mutant proteins have shown an expanded polyglutamine tract in SCA1, SCA2, MJD/SCA3, SCA6, SCA7, and DRPLA; a glycine-to-arginine substitution was found in SCA6 as well. Recently, an untranslated (CTG)n expansion on chromosome 13q was described as being the cause of SCA8. We have now (1) assessed the repeat size in a group of patients with ataxia and a large number of controls, (2) examined the intergenerational transmission of the repeat, and (3) estimated the instability of repeat size in the sperm of one patient and two healthy controls. Normal SCA8 chromosomes showed an apparently trimodal distribution, with classes of small (15-21 CTGs), intermediate (22-37 CTGs), and large (40-91 CTGs) alleles; large alleles accounted for only0.7% of all normal-size alleles. No expanded alleles (>/=100 CTGs) were found in controls. Expansion of the CTG tract was found in five families with ataxia; expanded alleles (all paternally transmitted) were characterized mostly by repeat-size contraction. There was a high germinal instability of both expanded and normal alleles: in one patient, the expanded allele (152 CTGs) had mostly contraction in size (often into the normal range); in the sperm of two normal controls, contractions were also more frequent, but occasional expansions into the upper limit of the normal size range were also seen. In conclusion, our results show (1) no overlapping between control (15-91) and pathogenic (100-152) alleles and (2) a high instability in spermatogenesis (both for expanded and normal alleles), suggesting a high mutational rate at the SCA8 locus.

Study of three intragenic polymorphisms in the Machado-Joseph disease gene (MJD1) in relation to genetic instability of the (CAG)n tract

Intergenerational instability is one of the most important features of the disease-associated trinucleotide expansions, leading to variation in size of the repeat among and within families, which manifests as variable age at onset and severity, and is probably the basis for the occurrence of anticipation. Several factors are known to affect the degree of instability, namely the type of repeated sequence, its initial size, the presence or absence of interruptions in the repetitive tract and the gender of the transmitting parent. A recent study demonstrated the effect of an intragenic polymorphism (C987GG/G987GG) in the Machado-Joseph disease causative gene, immediately downstream of the CAG repeat, on the intergenerational instability of the expanded repeat. Surprisingly, there was an effect not only of the specific allele in cis to the disease chromosome, but also of the allele on the normal chromosome, suggesting the existence of an interaction between the normal and expanded alleles that affects the fidelity of replication of the (CAG)n tract. This effect could be a direct effect of the polymorphism studied or, alternatively, this polymorphism could be in disequilibrium with some other flanking sequence which affects the instability of the repetitive (CAG)n tract. In order to confirm the previous results in a different population and to distinguish between a direct and indirect effect of the CGG/GGG polymorphism, we typed 70 parent-progeny pairs for which the variation in the (CAG)n length in the MJD1 gene was known, for three intragenic polymorphisms: C987GG/G987GG and two additional, newly described ones, TAA1118/TAC1118 and A669TG/G669TG. We also typed a control population of 125 individuals for the A669TG/G669TG, C987GG/G987GG and TAA1118/TAC1118 polymorphisms, in an attempt to identify any association between haplotype and (CAG)n length in normal chromosomes, suggestive of an instability-predisposing effect of the repeat-flanking sequences, which could have led to the origin of the MJD mutation in the human population. We confirmed the effect of the C987GG/G987GG polymorphism on intergenerational instability when present in trans. Our results suggest that this effect is restricted to a small region of the gene, immediately downstream of the CAG repeat, which includes this particular nucleotide substitution and the stop codon of the MJD1 cDNA, and is not a more widespread chromosomal effect. The lack of a significant association of any specific intragenic haplotype with larger CAG repeats in normal chromosomes, together with the absence of an effect of the intragenic haplotype in cis on the intergenerational instability of the expanded (CAG)n in MJD families does not indicate the existence of an instability-predisposing haplotype.

Traumatic fractures of primary molars: a case report

Dental trauma occurs very often in children and its consequences vary from tiny fractures to the complete avulsion of the tooth. According to Andreasen, 86.5% of incidents of dental trauma suffered by preschool children cause injury to maxillary primary incisors, whereas only 0.5% cause injury to primary molars. This case report is of a male patient aged 7 years who had fallen down a month before, struck his chin against a step, and fractured the maxillary and mandibular left primary second molars (65 and 75) and the mandibular right primary second molar (85). The 65 required only smoothing of sharp edges, 75 received endodontic treatment and a stainless steel crown, and 85 was extracted and a space maintainer fitted. The early diagnosis of fractures of posterior teeth is very important; a thorough examination of all posterior teeth should be made, especially when child suffers trauma to the chin region.

Evolution of subpatent parasitaemia in Trypanosoma cruzi chronically infected mice with the help of a cyclophosphamide amplification transfer assay

We have evaluated the sensitivity of the classical blood subinoculation method, modified through cyclophosphamide treatment of transferred mice, for the detection of occult parasitaemias in Trypanosoma cruzi chronically infected mice. Besides its simplicity, the method was shown to be highly sensitive for both the "chronic" phase parasites (99% of chronic cases were shown to harbour occult parasitaemias) and for the acute phase parasites (T. cruzi could be detected in 53.8% of animals transferred with one Y strain parasite and in 20% of animals transferred with one CL strain parasite). Using acute phase bloodforms, the assay proved to be more sensitive than conventional subinoculation when dealing with the CL, but not the Y strain of the parasite. With the help of this parasite detection tool, we have studied during a one year period, the evolution of subpatent parasitaemias in a group of mice which survived through chemotherapy from lethal acute phase of T. cruzi infection. Cyclophosphamide transfer assay revealed occult parasitaemias in 100% of the chronic animals, nevertheless, continuous and discontinuous patterns of positivity were observed.