Characterization of pupil responses to blue and red light stimuli in autosomal dominant retinitis pigmentosa due to NR2E3 mutation.

PURPOSE: We characterized the pupil responses that reflect rod, cone, and melanopsin function in a genetically homogeneous cohort of patients with autosomal dominant retinitis pigmentosa (adRP). METHODS: Nine patients with Gly56Arg mutation of the NR2E3 gene and 12 control subjects were studied. Pupil and subjective visual responses to red and blue light flashes over a 7 log-unit range of intensities were recorded under dark and light adaptation. The pupil responses were plotted against stimulus intensity to obtain red-light and blue-light response curves. RESULTS: In the dark-adapted blue-light stimulus condition, patients showed significantly higher threshold intensities for visual perception and for a pupil response compared to controls (P = 0.02 and P = 0.006, respectively). The rod-dependent, blue-light pupil responses decreased with disease progression. In contrast, the cone-dependent pupil responses (light-adapted red-light stimulus condition) did not differ between patients and controls. The difference in the retinal sensitivity to blue and red stimuli was the most sensitive parameter to detect photoreceptor dysfunction. Unexpectedly, the melanopsin-mediated pupil response was decreased in patients (P = 0.02). CONCLUSIONS: Pupil responses of patients with NR2E3-associated adRP demonstrated reduced retinal sensitivity to dim blue light under dark adaptation, presumably reflecting decreased rod function. Rod-dependent pupil responses were quantifiable in all patients, including those with non-recordable scotopic electroretinogram, and correlated with the extent of clinical disease. Thus, the chromatic pupil light reflex can be used to monitor photoreceptor degeneration over a larger range of disease progression compared to standard electrophysiology.

The Rank Lecture: Has imaging told us anything new about human visual organisation?

The functional architecture of the occipital cortex is being studied with increasing detail. Functional and structural MR based imaging are altering views about the organisation of the human visual system. Recent advances have ranged from comparative studies with non-human primates to predictive scanning. The latter multivariate technique describes with sub-voxel resolution patterns of activity that are characteristic of specific visual experiences. One can deduce what a subject experienced visually from the pattern of cortical activity recorded. The challenge for the future is to understand visual functions in terms of cerebral computations at a mesoscopic level of description and to relate this information to electrophysiology. The principal medical application of this new knowledge has focused to a large extent on plasticity and the capacity for functional reorganisation. Crossmodality visual-sensory interactions and cross-correlations between visual and other cerebral areas in the resting state are areas of considerable current interest. The lecture will review findings over the last two decades and reflect on possible roles for imaging studies in the future.

On the function of proton-gated ion channels ASICs and TRPV1 : a patch-clamp study

AbstractAcidosis is encountered during tissue inflammation and triggers pain in humans. H+-gated ion channels are expressed at high levels in sensory neurons of the peripheral nervous system. Ion channels from two different families present the required pH sensitivity to detect the acidosis associated with peripheral inflammation: Acid-Sensing Ion Channels (ASICs) and the Transient Receptor Potential Vanilloid-1 (TRPV1) channel.ASICs are members of the Degenerin/Epithelial Na+ Channel family of ion channels. Six ASIC subunits have been identified in mammals (ASICla, -lb, -2a, -2b, -3 and -4). ASICs form In-activated voltage-insensitive homo- or heterotrimeric Na+ channels. TRPV1 is a member of the TRP family of ion channels and forms non-selective cation channels that mediate a sustained current. TRPV1 is activated by H+, heat (T>43°C), lipids, capsaicin, voltage and other stimuli. A stimulus can increase TRPV1 response to a different stimulus. For example H+ can shift the capsaicin concentration dependence of TRPV1 to lower values. ASICs and TRPV1 have been shown to be involved in inflammatory pain. Using the patch-clamp technique, we studied different aspects of the function of ASICs and TRPV1 in the physiological context of pain.In the first part of this thesis, we characterize the effect of a temperature increase from 25 to 35°C on the function of ASICs and TRPV1 in transfected CHO cells and primary cultures of rat DRG sensory neurons. ASICs give rise to transient currents while TRPV1 mediates a sustained current. In addition, ASICs and TRPV1 respond to H+ with distinct pH dependences. We assess the relative contribution of ASICs and TRPV1 to H+-evoked electrical signaling in rat DRG neurons and we conclude that ASICs are the most important pH sensors in the pH range 7.4 to 6.0 at 35°C in sensory neurons.ASICs and TRPV1 are expressed in the epithelium lining the lumen of the bladder (urothelium). The Bladder Pain Syndrome/Interstitial Cystitis (BPS/IC) is a painful condition associated with a dysfunction of the urothelial barrier and with inflammation. In the second part of this thesis, we show that human urothelial cells -the cell line TEU2 and primary cultures of human bladder urothelium- express functional ASICs but no functional TRPV1 channels. In addition, we show that the levels of ASIC2 and ASIC3 mRNA are increased in the urothelium of patients suffering from BPS/IC. These data suggest that ASICs are involved in the pathology of BPS/IC.Finally, we demonstrate that APETx2 inhibits the sensory neuron specific voltage-dependent Na+ channel Nav1.8. APETx2 was previously shown to inhibit homo- or heterotrimeric ASIC3- containing channels with IC5o from 0.08 to 1 μΜ. We show that APETx2 also inhibits Nav1.8 with an ICsoof «2.6 μΜ. APETx2 reduces the maximal conductance and induces a depolarizing shift in the voltage dependence of activation of Nav1.8. In current-clamp experiments, APETx2 reduces the number of action potentials (APs) evoked by a current ramp. Nav1.8 mediates most of the current during the AP upstroke and has been shown to be an important mediator of inflammatory pain. The fact that APETx2 inhibits two ion channels involved in inflammatory pain suggests that APETx2 or derivatives may represent novel analgesic compounds.RésuméL'acidose tissulaire est observée durant l'inflammation et entraine la douleur chez l'humain. Des canaux ioniques activés par les protons (H+) sont fortement exprimés dans les neurones sensoriels du système nerveux périphérique. De ceux-ci, les Acid-Sensing Ion Channels [ASICs) et Transient Receptor Potential Vanilloid-1 (TRPV1) présentent une sensibilité adéquate à l'acidité pour servir de détecteurs d'acidose.Les ASICs sont membres de la famille Degenerin/Epithelial Na* Channel. Six sous-unités ASIC ont été identifiées chez les mammifères (ASICla, -lb, -2a, -2b, -3 et -4). Les ASICs forment des canaux sélectifs au Na\ insensibles au voltage et activés par les H+. Les canaux fonctionnels sont des homo- ou hétérotrimères de sous-unités ASIC. TRPV1 est un membre de la famille TRP de canaux ioniques. Les canaux TRPV1 sont activés par les H+, la chaleur (T>43°Ç), les lipides, la capsaicine, le voltage et d'autres stimulus. L'activation de TRPV1 entraine un courant soutenu non-sélectif. Un stimulus peut augmenter la réponse de TRPV1 à un autre stimulus. Les H+ peuvent, par exemple, induire un décalage vers des valeurs plus faibles de la courbe de dépendance à la concentration de TRPV1 pour la capsaicine. Il a été démontré que les ASICs et TRPV1 sont impliqués dans la douleur inflammatoire. En utilisant la technique du patch-clamp, nous avons étudié différents aspects de la fonction des ASICs et de TRPV1 dans des contextes associés à la douleur.Dans la première partie de cette thèse, nous caractérisons l'effet d'une augmentation de température de 25 à 35°C sur la fonction des canaux ASICs et TRPV1, dans des cellules CHO transfectées et dans des cultures primaires de neurones sensoriels (DRG) de rat. L'activation des ASICs entraine l'apparition d'un courant transitoire tandis que l'activation de TRPV1 entraine un courant soutenu. De plus, les ASICs et TRPV1 possèdent des dépendances au pH différentes. Nous évaluons la contribution relative des ASICs et de TRPV1 au signalement électrique induit par les H+ et nous concluons que les ASICs sont les senseurs d'acidité les plus importants dans les neurones sensoriels, dans le domaine de pH de 7.4 à 6.0, à température corporelle.Les ASICs et TRPV1 sont exprimés dans l'épithélium recouvrant l'intérieur de la vessie (l'urothélium). Le Bladder Pain Syndrome/Interstitial Cystitis (BPS/IC) est une condition médicale douloureuse associée à une dysfonction de la barrière urothéliale et à une inflammation. Dans la seconde partie de cette thèse, nous démontrons que des cellules urothéliales (de la lignée cellulaire TEU2) et des cellules provenant de cultures primaires d'épithéliums de vessies humaines expriment des canaux ASIC fonctionnels mais pas de TRPV1 fonctionnels. De plus, nous montrons que le niveau d'expression de ASIC2 et -3 est augmenté dans l'urothélium de la vessie de patients souffrant de BPS/IC. Ces données suggèrent que les ASICs sont impliqués dans la pathologie BPS/IC.Pour finir, nous démontrons que la toxine APETx2 inhibe le canal spécifique aux neurones sensoriels Nav1.8, un membre de la famille des canaux sodiques dépendants du potentiel. Il a été démontré précédemment que la toxine APETx2 inhibe les canaux contenant une ou plusieurs sous-unités ASIC3 avec un ICso entre 0.08 et 1 μΜ. Nous montrons que la toxine APETx2 inhibe Nav1.8 avec un IC50 de «2.6 μΜ. La toxine APETx2 réduit la conductance maximale et induit un décalage de la dépendance au potentiel de Nav1.8 vers des valeurs plus positives. Dans des expériences de courant imposé sur des neurones sensoriels, la toxine APETx2 réduit le nombre de potentiels d'action induits par une rampe de courant. Nav1.8 est responsable de la majeure partie du courant durant la phase ascendante du potentiel d'action et a été démontré comme étant un médiateur important de la douleur inflammatoire. L'inhibition de deux types de canaux, impliqués dans la douleurs inflammatoire, par la toxine APETx2, suggère que cette dernière ou ses dérivés représentent des composés analgésiques prometteurs.

Evaluation of two minimally invasive techniques for electroencephalogram recording in wild or freely behaving animals.

Insight into the function of sleep may be gained by studying animals in the ecological context in which sleep evolved. Until recently, technological constraints prevented electroencephalogram (EEG) studies of animals sleeping in the wild. However, the recent development of a small recorder (Neurologger 2) that animals can carry on their head permitted the first recordings of sleep in nature. To facilitate sleep studies in the field and to improve the welfare of experimental animals, herein, we test the feasibility of using minimally invasive surface and subcutaneous electrodes to record the EEG in barn owls. The EEG and behaviour of four adult owls in captivity and of four chicks in a nest box in the field were recorded. We scored a 24-h period for each adult bird for wakefulness, slow-wave sleep (SWS), and rapid-eye movement (REM) sleep using 4 s epochs. Although the quality and stability of the EEG signals recorded via subcutaneous electrodes were higher when compared to surface electrodes, the owls' state was readily identifiable using either electrode type. On average, the four adult owls spent 13.28 h awake, 9.64 h in SWS, and 1.05 h in REM sleep. We demonstrate that minimally invasive methods can be used to measure EEG-defined wakefulness, SWS, and REM sleep in owls and probably other animals.

Nineteenth century research on cell death.

This paper reviews research on cell death in the 19th C. The first report of cell death was by Vogt in 1842, which was remarkably soon after the establishment of the cell theory by Schleiden and Schwann between 1838 and 1842. Initial studies on cell death, including that of Vogt, focused on its occurrence in metamorphosis (Vogt, 1842; Prévost and Lebert, 1844; Weismann, 1863-1866) or in blatant pathology (Virchow, 1858), but as histological techniques improved it was found to be involved in more subtle roles in numerous situations including endochondral ossification (Stieda, 1872), ovarian follicle atresia (Flemming, 1885), cell turnover (Nissen, 1886), the wholesale loss of a population of sensory neurons in fish (Beard, 1889), and the naturally occurring histogenetic death of myocytes (Felix, 1889) and neurons (Collin, 1906). The current categorization of cell death into about three main morphological types has 19th century roots in that apoptosis was well described by Flemming (1885), who called it chromatolysis, and various authors including Noetzel (1895) proposed a threefold classification. This article is part of a Special Issue entitled "Apoptosis: Four Decades Later".

The central projection of cephalic mechanosensory axons in the haematophagous bug Triatoma infestans

The projections of mechanosensory hairs located on the dorsal and lateral head of the adult haematophagous bug Triatoma infestans were analyzed by means of cobalt filling. Axons run into the anterior and posterior tegumentary nerve and project through the brain to the ventral nerve cord. The fibres are small in diameter and run as a fascicle. Some branches run into suboesophageal and prothoracic centres; others run as far as to the mesothoracic ganglion. These sensory projections resemble that of wind-sensitive head hairs of the locust. The functional role of this sensory system in this species is discussed.

Temperament in Bach’s Well-tempered clavier: a historical survey and a new evaluation according to dissonance theory

After a historical survey of temperament in Bach’s Well-Tempered Clavier by Johann Sebastian Bach, an analysis of the work has been made by applying a number of historical good temperaments as well as some recent proposals. The results obtained show that the global dissonance for all preludes and fugues in major keys can be minimized using the Kirnberger II temperament. The method of analysis used for this research is based on the mathematical theories of sensory dissonance, which have been developed by authors such as Hermann Ludwig Ferdinand von Helmholtz, Harry Partch, Reinier Plomp, Willem J. M. Levelt and William A. Sethares

Promoter architecture of mouse olfactory receptor genes.

Odorous chemicals are detected by the mouse main olfactory epithelium (MOE) by about 1100 types of olfactory receptors (OR) expressed by olfactory sensory neurons (OSNs). Each mature OSN is thought to express only one allele of a single OR gene. Major impediments to understand the transcriptional control of OR gene expression are the lack of a proper characterization of OR transcription start sites (TSSs) and promoters, and of regulatory transcripts at OR loci. We have applied the nanoCAGE technology to profile the transcriptome and the active promoters in the MOE. nanoCAGE analysis revealed the map and architecture of promoters for 87.5% of the mouse OR genes, as well as the expression of many novel noncoding RNAs including antisense transcripts. We identified candidate transcription factors for OR gene expression and among them confirmed by chromatin immunoprecipitation the binding of TBP, EBF1 (OLF1), and MEF2A to OR promoters. Finally, we showed that a short genomic fragment flanking the major TSS of the OR gene Olfr160 (M72) can drive OSN-specific expression in transgenic mice.

COSMOS : gestor de continguts accessibles

Cada cop són més els usuaris que es troben amb la necessitat de posar els seus serveis i/o productes a Internet. Un cop que els usuaris prenen aquesta decisió, és habitual que es trobin amb eines poc intuïtives i complexes que dificulten la tasca de manteniment de la informació que es vol mostrar al portal web. La finalitat d'aquest projecte és apropar les tasques de manteniment als usuaris per tal que puguin modificar els continguts publicats al seu portal web, independentment de la seves capacitats tecnològiques o sensorials.

Ultrastructural alterations in adult Schistosoma mansoni caused by artemether

Progress has been made over the last decade with the development and clinical use of artemether as an agent against major human schistosome parasites. The tegument has been identified as a key target of artemether, implying detailed studies on ultrastructural damage induced by this compound. We performed a temporal examination, employing a transmission electron microscope to assess the pattern and extent of ultrastructural alterations in adult Schistosoma mansoni harboured in mice treated with a single dose of 400 mg/kg artemether. Eight hours post-treatment, damage to the tegument and subtegumental structures was seen. Tegumental alterations reached a peak 3 days after treatment and were characterized by swelling, fusion of distal cytoplasma, focal lysis of the tegumental matrix and vacuolisation. Tubercles and sensory organelles frequently degenerated or collapsed. Typical features of subtegumental alterations, including muscle fibres, syncytium and parenchyma tissues, were focal or extensive lysis, vacuolisation and degeneration of mitochondria. Severe alterations were also observed in gut epithelial cells and vitelline cells of female worms. Our findings of artemether-induced ultrastructural alterations in adult S. mansoni confirm previous results obtained with juvenile S. mansoni and S. japonicum of different ages.

Speech by Mr. Micheál Martin TD – Meeting The Challenges Of Cultural Diversity In The Irish Healthcare Sector

It gives me great pleasure to accept the invitation to address this conference on “Meeting the Challenges of Cultural Diversity in the Irish Healthcare Sector” which is being organised by the Irish Health Services Management Institute in partnership with the National Consultative Committee on Racism and Interculturalism. The conference provides an important opportunity to develop our knowledge and understanding of the issues surrounding cultural diversity in the health sector from the twin perspectives of patients and staff. Cultural diversity has over recent years become an increasingly visible aspect of Irish society bringing with it both opportunities and challenges. It holds out great possibilities for the enrichment of all who live in Ireland but it also challenges us to adapt creatively to the changes required to realise this potential and to ensure that the experience is a positive one for all concerned but particularly for those in the minority ethnic groups. In the last number of years in particular, the focus has tended to be on people coming to this country either as refugees, asylum seekers or economic migrants. Government figures estimate that as many as 340,000 immigrants are expected in the next six years. However ethnic and cultural diversity are not new phenomena in Ireland. Travellers have a long history as an indigenous minority group in Ireland with a strong culture and identity of their own. The changing experience and dynamics of their relationship with the wider society and its institutions over time can, I think, provide some valuable lessons for us as we seek to address the more numerous and complex issues of cultural diversity which have arisen for us in the last decade. Turning more specifically to the health sector which is the focus of this conference, culture and identity have particular relevance to health service policy and provision in that The first requirement is that we in the health service acknowledge cultural diversity and the differences in behaviours and in the less obvious areas of values and beliefs that this often implies. Only by acknowledging these differences in a respectful way and informing ourselves of them can we address them. Our equality legislation – The Employment Equality Act, 1998 and the Equal Status Act, 2000 – prohibits discrimination on nine grounds including race and membership of the Traveller community. The Equal Status Act prohibits discrimination on an individual basis in relation to the nine grounds while for groups it provides for the promotion of equality of opportunity. The Act applies to the provision of services including health services. I will speak first about cultural diversity in relation to the patient. In this respect it is worth mentioning that the recognition of cultural diversity and appropriate responses to it were issues which were strongly emphasised in the public consultation process which we held earlier this year in the context of developing National Anti-Poverty targets for the health sector and also our new national health strategy. Awareness and sensitivity training for staff is a key requirement for adapting to a culturally diverse patient population. The focus of this training should be the development of the knowledge and skills to provide services sensitive to cultural diversity. Such training can often be most effectively delivered in partnership with members of the minority groups themselves. I am aware that the Traveller community, for example, is involved in in-service training for health care workers. I am also aware that the National Consultative Committee on Racism and Interculturalism has been involved in training with the Eastern Regional Health Authority. We need to have more such initiatives. A step beyond the sensitivity training for existing staff is the training of members of the minority communities themselves as workers in our health services. Again the Traveller community has set an example in this area with its Primary Health Care Project for Travellers. The Primary Health Care for Travellers Project was established in 1994 as a joint partnership initiative with the Eastern Health Board and Pavee Point, with ongoing technical assistance being provided from the Department of Community Health and General Practice, Trinity College, Dublin. This project was the first of its kind in the country and has facilitated The project included a training course which concentrated on skills development, capacity building and the empowerment of Travellers. This confidence and skill allowed the Community Health Workers to go out and conduct a baseline survey to identify and articulate Travellers’ health needs. This was the first time that Travellers were involved in this process; in the past their needs were assumed. The results of the survey were fed back to the community and they prioritised their needs and suggested changes to the health services which would facilitate their access and utilisation. Ongoing monitoring and data collection demonstrates a big improvement in levels of satisfaction and uptake and ulitisation of health services by Travellers in the pilot area. This Primary Health Care for Travellers initiative is being replicated in three other areas around the country and funding has been approved for a further 9 new projects. This pilot project was the recipient of a WHO 50th anniversary commemorative award in 1998. The project is developing as a model of good practice which could inspire further initiatives of this type for other minority groups. Access to information has been identified in numerous consultative processes as a key factor in enabling people to take a proactive approach to managing their own health and that of their families and in facilitating their access to health services. Honouring our commitment to equity in these areas requires that information is provided in culturally appropriate formats. The National Health Promotion Strategy 2000-2005, for example, recognises that there exists within our society many groups with different requirements which need to be identified and accommodated when planning and implementing health promotion interventions. These groups include Travellers, refugees and asylum seekers, people with intellectual, physical or sensory disability and the gay and lesbian community. The Strategy acknowledges the challenge involved in being sensitive to the potential differences in patterns of poor health among these different groups. The Strategic aim is to promote the physical, mental and social well-being of individuals from these groups. The objective of the Strategy on these issues are: While our long term aim may be to mainstream responses so that our health services is truly multicultural, we must recognise the need at this point in time for very specific focused responses particularly for groups with poor health status such as Travellers and also for refugees and asylum seekers. In the case of refugees and asylum seekers examples of targeted services are screening for communicable diseases – offered on a voluntary basis – and psychological support services for those who have suffered trauma before coming here. The two approaches of targeting and mainstreaming are not mutually exclusive. A combination of both is required at this point in time but the balance between them must be kept under constant review in the light of changing needs. A major requirement if we are to meet the challenge of cultural diversity is an appropriate data and research base. I think it is important that we build up our information and research data base in partnership with the minority groups themselves. We must establish what the health needs of diverse groups are; we must monitor uptake of services and how well we are responding to needs and we must monitor outcomes and health status. We must also examine the impact of the policies in other sectors on the health of minority groups. The National Health Information Strategy, currently being developed, and the recently published National Strategy for Health Research – Making Knowledge Work for Health provide important frameworks within which we can improve our data and research base. A culturally diverse health sector workforce – challenges and opportunities The Irish health service can benefit greatly from successful international recruitment. There has been a strong non-national representation amongst the medical profession for more than 30 years. More recently there have been significant increases in other categories of health service workers from overseas. The Department recognises the enormous value that overseas recruitment brings over a wide range of services and supports the development of effective and appropriate recruitment strategies in partnership with health service employers. These changes have made cultural diversity an important issue for all health service organisations. Diversity in the workplace is primarily about creating a culture that seeks, respects, values and harnesses difference. This includes all the differences that when added together make each person unique. So instead of the focus being on particular groups, diversity is about all of us. Change is not about helping “them” to join “us” but about critically looking at “us” and rooting out all aspects of our culture that inappropriately exclude people and prevent us from being inclusive in the way we relate to employees, potential employees and clients of the health service. International recruitment benefits consumers, Irish employees and the overseas personnel alike. Regardless of whether they are employed by the health service, members of minority groups will be clients of our service and consequently we need to be flexible in order to accommodate different cultural needs. For staff, we recognise that coming from other cultures can be a difficult transition. Consequently health service employers have made strong efforts to assist them during this period. Many organisations provide induction courses, religious facilities (such as prayer rooms) and help in finding suitable accommodation. The Health Service Employers Agency (HSEA) is developing an equal opportunities/diversity strategy and action plans as well as training programmes to support their implementation, to ensure that all health service employment policies and practices promote the equality/diversity agenda to continue the development of a culturally diverse health service. The management of this new environment is extremely important for the health service as it offers an opportunity to go beyond set legal requirements and to strive for an acceptance and nurturing of cultural differences. Workforce cultural diversity affords us the opportunity to learn from the working practices and perspectives of others by allowing personnel to present their ideas and experience through teamwork, partnership structures and other appropriate fora, leading to further improvement in the services we provide. It is important to ensure that both personnel units and line managers communicate directly with their staff and demonstrate by their actions that they intend to create an inclusive work place which doesn´t demand that minority staff fit. Contented, valued employees who feel that there is a place for them in the organisation will deliver a high quality health service. Your conference here today has two laudable aims – to heighten awareness and assist health care staff to work effectively with their colleagues from different cultural backgrounds and to gain a greater understanding of the diverse needs of patients from minority ethnic backgrounds. There is a synergy in these aims and in the tasks to which they give rise in the management of our health service. The creative adaptations required for one have the potential to feed into the other. I would like to commend both organisations which are hosting this conference for their initiative in making this event happen, particularly at this time – Racism in the Workplace Week. I look forward very much to hearing the outcome of your deliberations. Thank you.

Influence of the in vivo deregulation of the expression of ntrk3 (trkc) on cortical development of a murine model of panic/anxiety disorder

Alteracions durant el desenvolupament cerebral produirien canvis en la connectivitat neuronal i la bioquímica cel•lular que podrien resultar en una disfunció cognitiva i/o emocional, desembocant a trastorns psiquiàtrics. Les neurotrofines intervenen en els processos del neurodesenvolupament i en la funcionalitat del cervell adult i, conseqüentment, serien bons candidats com a factors de predisposició en diverses malalties mentals. S’ha suggerit la implicació del receptor de la neurotrofina 3, TrkC, en el trastorn de pànic. Nosaltres proposem que la sobreexpressió del gen NTRK3 (TrkC) és un mediador comú dels desencadenants genètics i ambientals d’aquest trastorn. Concretament, la seva desregulació podria produir canvis estructurals i funcionals a l’escorça cerebral dels pacients pel seu paper durant l’establiment dels circuïts corticals i la neuroplasticitat a l’adult, probablement esdevenint elements de predisposició a patir atacs de pànic. Els objectius principals d’aquest treball han estat: 1/determinar la contribució específica del gen NTRK3 a les alteracions de l’escorça cerebral observades en pacients, utilitzant un model murí modificat genèticament (TgNTRK3), i 2/analitzar l’impacte específic de la sobreexpressió de NTRK3 sobre la corticogènesi durant estadis embrionaris o postnatals estudiant la neurogènesi i la neuritogènesi. Els resultats indiquen que la sobreexpressió de NTRK3 als ratolins produeix una reducció del gruix de l’escorça frontal, recapitulant la hipofrontalitat dels pacients, que comportaria una menor inhibició dels nuclis subcorticals del sistema límbic com l’amígdala, i alteracions citoarquitectòniques a l’escorça prefrontal medial que recolzen la hipòtesi del seu mal funcionament. Tanmateix, els ratolins TgNTRK3 presenten canvis estructurals a l’escorça somatosensorial, suggerint que el processament de la informació sensorial podria estar alterat, el que encara no s’ha explorat en pacients. La sobreexpressió de NTRK3 també afecta la neuritogènesi en cultius primaris corticals i modifica la resposta de les neurones a l’estimulació amb neurotrofines. Per tant, el fenotip cortical adult dels TgNTRK3 podria dependre d’alteracions durant la corticogènesi.

Differential distribution of two microtubule-associated proteins, MAP2 and MAP5, during chick dorsal root ganglion development in situ and in culture.

Microtubule-associated proteins (MAPs) are essential components necessary for the early growth process of axons and dendrites, and for the structural organization within cells. Both MAP2 and MAP5 are involved in these events, MAP2 occupying a role predominantly in dendrites, and MAP5 being involved in both axonal and dendritic growth. In the chick dorsal root ganglia, pseudo-unipolar sensory neurons have a T-shaped axon and are devoid of any dendrites. Therefore, they offer an ideal model to study the differential expression of MAPs during DRG development, specifically during axonal growth. In this study we have analyzed the expression and localization of MAP2 and MAP5 isoforms during chick dorsal root ganglia development in vivo, and in cell culture. In DRG, both MAPs appeared as early as E5. MAP2 consists of the 3 isoforms MAP2a, b and c. On blots, no MAP2a could be found at any stage. MAP2b increased between E6 and E10 and thereafter diminished slowly in concentration, while MAP2c was found between stages E6 and E10 in DRG. By immunocytochemistry, MAP2 isoforms were mainly located in the neuronal perikarya and in the proximal portion of axons, but could not be localized to distal axonal segments, nor in sciatic nerve at any developmental stage. On blots, MAP5 was present in two isoforms, MAP5a and MAP5b. The concentration of MAP5a was highest at E6 and then decreased to a low level at E18. In contrast, MAP5b increased between E6 and E10, and rapidly decreased after E14. Only MAP5a was present in sciatic nerve up to E14. Immunocytochemistry revealed that MAP5 was localized mainly in axons, although neuronal perikarya exhibited a faint immunostaining. Strong staining of axons was observed between E10 and E14, at a time coincidental to a period of intense axonal outgrowth. After E14 immunolabeling of MAP5 decreased abruptly. In DRG culture, MAP2 was found exclusively in the neuronal perikarya and the most proximal neurite segment. In contrast, MAP5 was detected in the neuronal cell bodies and all along their neurites. In conclusion, MAP2 seems involved in the early establishment of the cytoarchitecture of cell bodies and the proximal axon segment of somatosensory neurons, while MAP5 is clearly related to axonal growth.

Manipulating sleep spindles - expanding views on sleep, memory, and disease.

Sleep spindles are distinctive electroencephalographic (EEG) oscillations emerging during non-rapid-eye-movement sleep (NREMS) that have been implicated in multiple brain functions, including sleep quality, sensory gating, learning, and memory. Despite considerable knowledge about the mechanisms underlying these neuronal rhythms, their function remains poorly understood and current views are largely based on correlational evidence. Here, we review recent studies in humans and rodents that have begun to broaden our understanding of the role of spindles in the normal and disordered brain. We show that newly identified molecular substrates of spindle oscillations, in combination with evolving technological progress, offer novel targets and tools to selectively manipulate spindles and dissect their role in sleep-dependent processes.

Differential distribution of thyroid hormone receptor isoform in rat dorsal root ganglia and sciatic nerve in vivo and in vitro.

Using autoradiographic techniques carried out under precise conditions we previously demonstrated that both sensory neurons and peripheral glial cells in dorsal root ganglia (DRG) or sciatic nerve, possess specific [125I]-labeled T3 binding sites. Thyroid hormone receptors (TR) include several isoforms (TR alpha(1), TR alpha(2), TR beta(1), TR beta(2...)) The present study demonstrates that while sensory neurons and peripheral glial cells both possess functional TR, they express a differential expression of TR isoforms. Using a panel of antisera to specific for the TR alpha-common (alpha(1) and alpha(2)), TR alpha-1 or TR beta-1 isoforms, we detected TRs isoform localization at the cellular level during DRG and sciatic nerve development and regeneration. Immunohistochemical analysis revealed that during embryonic life, sensory neurons express TR alpha-common and TR beta-1 rather than TR alpha-1. The number of TR alpha-common and TR beta-1 positive neurons as well as the intensity of labeling increased during the first two postnatal weeks and remained more or less stable in adult life. TR alpha-1 immunoreactivity, which was undetectable in embryonic sensory neurons, became discreetly visible in neurons after birth. In developing DRG and sciatic nerves, Schwann cells exhibited TR alpha-common and TR alpha-1 rather than TR beta-1 immunolabeling. The appearance of TR alpha-common and alpha-1 isoform immunoreactivity in the sciatic nerve was restricted to a short period ranging from E17 up to two postnatal weeks. By comparing TR alpha-common and TR alpha-1 immunostaining we can deduce that Schwann cells primarily express TR alpha-1. Afterwards, in adult rat sciatic nerve TR alpha isoforms was no more detected. However transection of sciatic nerve caused a reexpression of TR alpha isoforms in degenerating nerve. The prevalence of TR alpha in Schwann cells in vivo was correlated with in vitro results. The differential expression of TR alpha and beta by sensory neurons and Schwann cells indicates that the feedback regulation of circulating thyroid hormone could occur by binding to either the alpha or beta TR isoforms. Moreover, the presence of multiple receptor isoforms in developing sensory neurons suggests that thyroid hormone uses multiple signaling pathways to regulate DRG and sciatic nerve development.