Nonvisual aspects of spatial knowledge: Wayfinding behavior of blind persons in Lisbon.

Blind individuals' wayfinding performance in complex urban environments is a complex phenomenon. This study investigates the wayfinding strategies of congenitally blind individuals in an urban context. The aim of the study was to assess the extent to which the environmental auditory cues are of primary importance for their wayfinding strategies. The study was conducted in Lisbon, Portugal. Results suggest that auditory information was the most used environmental cue and that a feeling of enclosure is the most important environmental feature during wayfinding. These results corroborate previous findings suggesting that increased familiarity with the environment results in more efficient wayfinding strategies, and that lack of environmental auditory cues could be compensated by a robust cognitive map. The study highlights multidimensional sensory experiences of urban environments and nonvisual aspects of spatial perception.

An mHealth intervention programme to promote healthy behaviours and prevent adolescent obesity (TeenPower): A study protocol.

AIM: This paper describes the design and rationale of multicenter practice-based research that aims to develop and evaluate an innovative mobile health (mHealth) intervention programme directed to promote healthy behaviours and prevent adolescent obesity. DESIGN: This study is designed as a non-randomized controlled trial with a three-arm structure. METHODS: Twelve to 16 years old participants will be recruited from schools, with access to the Internet and smartphone/tablet devices. The intervention group will be invited to engage in the TeenPower mHealth programme and divided into two subgroups: Group A (additionally engaged in a structured school-based intervention programme) and Group B (only engaged in the mHealth programme). The mHealth app includes educational resources, self-monitoring, social support, interactive training modules and motivational tools. The control group will only follow the structured school-based intervention programme. The intervention length will be 3 months, including the direct support of an interdisciplinary team (nursing, nutrition, sports, psychology, among others). This research was approved and funded in August 2017. DISCUSSION: The positive evaluation of the intervention programme will stimulate the inclusion of technologies in the promotion of salutogenic behaviours and obesity prevention. IMPACT: Adolescent obesity reached epidemic proportions. It is urgent to find effective prevention strategies to induce change at the individual, family and community level. If effective, this protocol can be used by health and exercise professionals in improving community interventions tailored to teenagers.

Qualidade de vida em idosos diabéticos assistidos na estratégia de saúde da família / Quality of life in elderly diabetics assisted in the family health strategy / Calidad de vida en ancianos diabéticos que reciben asistencia en la estrategia salud de la familia

No Brasil, os idosos apresentam mais de uma doença crônica, destacando-se o Diabetes Mellitus, entre as cinco principais patologias que afetam essa população. O objetivo deste estudo é analisar a qualidade de vida em idosos diabéticos assistidos na Estratégia Saúde da Família. Trata-se de um estudo epidemiológico, descritivo, de corte transversal realizado no município de Recife, Pernambuco, Brasil. Utilizou-se o instrumento Medical Outcomes Study Short-Form-36 para avaliar a qualidade de vida. Os dados foram coletados por meio de entrevistas domiciliares e consultas aos prontuários disponíveis nas unidades básicas de saúde, no período de julho a novembro de 2012, e analisados pelo programa Statistical Package for Social Sciences for Windows, versão 14.0. Participaram do estudo 202 idosos. Os resultados apontaram que a maioria dos idosos era aposentada e possuía rendimento entre um e dois salários mínimos, prevalecendo mulheres idosas, idosos jovens, e com baixa escolaridade. Observou-se piores escores de qualidade de vida (estatisticamente significante) nas idosas e naqueles que não executavam prática de atividade física. Concluiu-se que a qualidade de vida de idosos diabéticos assistidos na Estratégia Saúde da Família apresentou escores baixos para a Qualidade de vida.

In Brazil, the elderly report more than one chronic disease, most notably Diabetes Mellitus, among the five major pathologies affecting the elderly population. The objective of this study is to analyze the quality of life in diabetic elderly people assisted in the Family Health Strategy. This is a descriptive, cross-sectional, epidemiological study conducted in the city of Recife, Pernambuco, Brazil. To describe health-related quality of life, the Medical Outcomes Study Short-Form-36 instrument was used to assess the quality of life in general. The data were collected by means of home interviews and consultations to the medical records available in the basic health units, from July to November 2012, and analyzed by the Statistical Package for Social Sciences for Windows, version 14.0. 202 elderly people participated in the study. The results showed that the majority of the elderly were retired and had income between one and two minimum wages, prevailing among elderly women, young old, and with low schooling. Worse quality of life scores (statistically significant) were found in the elderly and in those who did not practice physical activity. It was possible to conclude that the quality of life of diabetic elderly people assisted in the Family Health Strategy showed low scores to the Quality of Life.

En Brasil los ancianos presentan más de una enfermedad crónica, destacándose la Diabetes Mellitus, entre las cinco principales patologías que afectan esa población. El objetivo de este estudio es analizar la calidad de vida en ancianos diabéticos asistidos en la Estrategia de Salud de la Familia. Tratase de un estudio epidemiológico, descriptivo, de corte transversal realizado en el municipio de Recife, Pernambuco, Brasil. Para describir la calidad de vida relacionada a la salud fue utilizado el instrumento Medical Outcomes Study Short-Form-36. Los datos fueron recolectados por medio de entrevistas domiciliarias y consultas a los prontuarios disponibles en las unidades básicas de salud, en el período de entre julio y noviembre de 2012, y analizados por el programa Statistical Package for Social Sciences for Windows, versión 14.0. Participaron del estudio 202 ancianos. Los resultados apuntaron que la mayoría de los ancianos era jubilada y poseía ingresos entre uno y dos salarios mínimos, prevaleciendo mujeres ancianas, ancianos jóvenes, y con baja escolaridad. Fueron observados peores escores de calidad de vida (estadísticamente significante) en las ancianas y en aquellos que no realizaban práctica de actividad física. Concluyóse que la calidad de vida de los ancianos diabéticos asistidos en la Estrategia de Salud de la Familia presentó escores bajos para la calidad de vida.

Effects of competing environmental variables and signage on route-choices in simulated everyday and emergency wayfinding situations.

This study examined the relative influence of environmental variables (corridor width and brightness) and signage (directional and exit signs), when presented in competition, on participants' route-choices in two situational variables (everyday vs. emergency), during indoor wayfinding in virtual environments. A virtual reality-based methodology was used. Thus, participants attempted to find a room (everyday situation) in a virtual hotel, followed by a fire-related emergency egress (emergency situation). Different behaviours were observed. In the everyday situation, for no-signs condition, participants choose mostly the wider and brighter corridors, suggesting a heavy reliance on the environmental affordances. Conversely, for signs condition, participants mostly complied with signage, suggesting a greater reliance on the signs rather than on the environmental cues. During emergency, without signage, reliance on environmental affordances seems to be affected by the intersection type. In the sign condition, the reliance on environmental affordances that started strong decreases along the egress route.

Behavioral compliance for dynamic versus static signs in an immersive virtual environment.

This study used an immersive virtual environment (IVE) to examine how dynamic features in signage affect behavioral compliance during a work-related task and an emergency egress. Ninety participants performed a work-related task followed by an emergency egress. Compliance with uncued and cued safety signs was assessed prior to an explosion/fire involving egress with exit signs. Although dynamic presentation produced the highest compliance, the difference between dynamic and static presentation was only statistically significant for uncued signs. Uncued signs, both static and dynamic, were effective in changing behavior compared to no/minimal signs. Findings are explained based on sign salience and on task differences. If signs must capture attention while individuals are attending to other tasks, salient (e.g., dynamic) signs are useful in benefiting compliance. This study demonstrates the potential for IVEs to serve as a useful tool in behavioral compliance research.

Neuroprotection by GDNF in the ischemic brain.

The glial cell line-derived neurotrophic factor (GDNF) was first identified as a survival factor for midbrain dopaminergic neurons, but additional studies provided evidences for a role as a trophic factor for other neurons of the central and peripheral nervous systems. GDNF regulates cellular activity through interaction with glycosyl-phosphatidylinositol-anchored cell surface receptors, GDNF family receptor-α1, which might signal through the transmembrane Ret tyrosine receptors or the neural cell adhesion molecule, to promote cell survival, neurite outgrowth, and synaptogenesis. The neuroprotective effect of exogenous GDNF has been shown in different experimental models of focal and global brain ischemia, by local administration of the trophic factor, using viral vectors carrying the GDNF gene and by transplantation of GDNF-expressing cells. These different strategies and the mechanisms contributing to neuroprotection by GDNF are discussed in this review. Importantly, neuroprotection by GDNF was observed even when administered after the ischemic injury.

Comparing two types of navigational interfaces for Virtual Reality.

Previous studies suggest significant differences between navigating virtual environments in a life-like walking manner (i.e., using treadmills or walk-in-place techniques) and virtual navigation (i.e., flying while really standing). The latter option, which usually involves hand-centric devices (e.g., joysticks), is the most common in Virtual Reality-based studies, mostly due to low costs, less space and technology demands. However, recently, new interaction devices, originally conceived for videogames have become available offering interesting potentialities for research. This study aimed to explore the potentialities of the Nintendo Wii Balance Board as a navigation interface in a Virtual Environment presented in an immersive Virtual Reality system. Comparing participants' performance while engaged in a simulated emergency egress allows determining the adequacy of such alternative navigation interface on the basis of empirical results. Forty university students participated in this study. Results show that participants were more efficient when performing navigation tasks using the Joystick than with the Balance Board. However there were no significantly differences in the behavioral compliance with exit signs. Therefore, this study suggests that, at least for tasks similar to the studied, the Balance Board have good potentiality to be used as a navigation interface for Virtual Reality systems.

Selection of a voice for a speech signal for personalized warnings: the effect of speaker's gender and voice pitch.

There is an increasing interest in multimodal technology-based warnings, namely those conveying speech-warning statements. This type of warning may be tailored to the situation as well as to the target user's characteristics. However, more information is needed on how to design these warnings in a way that ensures intelligibility, promotes compliance and reduces the potential for annoyance. In this context, this paper reports an exploratory study whose main purpose was to assist the selection of a synthesized voice for a subsequent compliance study with personalized (i.e., using the person's name) technology-based warnings using Virtual Reality. Participants were requested to listen to speech signals, gathered from a speech synthesizer and post-processed in order to change the pitch perception, and then these were evaluated by fulfilling the MOS-X questionnaire. After that, the participants ranked the voices according to their preference. The effects of the speaker's gender and voice pitch, on both ratings and ranking were assessed. The preference of the male and female listeners for a talker's voice gender was also investigated. The results show that participants mostly prefer as first choice the high-pitched female voice, which also gathered the highest overall score in the MOS-X questionnaire. No significant influence of the participants' gender was found on the assessed measures.

What should I do?--a study about conflicting and ambiguous warning messages.

Warnings are intended to reduce accidents caused by hazards. Behavioral compliance is the most important measure of warning effectiveness. However, in result of diverse circumstances (e.g., distraction, misuse, negligence), conflicting or ambiguous safety messages can be perceived. Since these are recurrent and can result in wrong behaviors encompassing severe consequences, such cases should be studied for safety purposes. We report findings on the participants' compliant behavior when performing a work-related task, while immersed in a virtual environment, and investigate the effect of conflicting messages on compliance with warnings. Two warnings (one regular and one with an appended out-of-order sign) and two types of signs (static and dynamic) were considered. The warning with the out-of-order sign configures the case of potentially conflicting messages. The gender effect was also investigated. The participants' behavior was assessed regarding to pushing a button as directed by the warnings. In the "out-of-order" warning, compliance was higher in the dynamic situation (53.3%) than in the static one (3.3%). Comparing with the non-conflicting warning, compliance was higher for both situations (static: 76.7%; dynamic: 100%). Women complied more than men. Although these results have limitations in their generalization, they are nonetheless relevant and deserve to be studied further.

Using virtual reality to assess user experience.

OBJECTIVE: The aim of this article is to discuss how user experience (UX) evaluation can benefit from the use of virtual reality (VR). BACKGROUND: UX is usually evaluated in laboratory settings. However, considering that UX occurs as a consequence of the interaction between the product, the user, and the context of use, the assessment of UX can benefit from a more ecological test setting. VR provides the means to develop realistic-looking virtual environments with the advantage of allowing greater control of the experimental conditions while granting good ecological validity. METHOD: The methods used to evaluate UX, as well as their main limitations, are identified.The currentVR equipment and its potential applications (as well as its limitations and drawbacks) to overcome some of the limitations in the assessment of UX are highlighted. RESULTS: The relevance of VR for UX studies is discussed, and a VR-based framework for evaluating UX is presented. CONCLUSION: UX research may benefit from a VR-based methodology in the scopes of user research (e.g., assessment of users' expectations derived from their lifestyles) and human-product interaction (e.g., assessment of users' emotions since the first moment of contact with the product and then during the interaction). APPLICATION: This article provides knowledge to researchers and professionals engaged in the design of technological interfaces about the usefulness of VR in the evaluation of UX.

Microglia of rat ventral midbrain recovers its resting state over time in vitro: let microglia rest before work.

Cortical or total brain cultures of microglia are commonly used as a model to study the inflammatory processes in Parkinson's disease. Here we characterize microglia cultures from rat ventral midbrain and evaluate their response to zymosan A. We used specific markers of microglia and evaluated the morphology, the phagocytic activity and reactive oxygen species (ROS) levels of the cells. During the first 10 days in vitro (DIV), cultures presented predominantly cells with a round morphology, expressing CD68 and with high phagocytic activity and ROS production. After 13 DIV, this tendency was reversed, with cultures showing higher number of ramified cells and fewer CD68(+) cells along with lower phagocytic and ROS production capability, suggesting that microglia must be kept in vitro for at least 13 days to recover its resting state. The exposure of cultures with less than 10 DIV to zymosan A significantly decreased cell viability. Exposure of cultures with 13 DIV to zymosan A (0.05, 0.5, or 5 microg/ml) increased the total cell number, the percentage of CD68(+) cells, and the phagocytic activity. Concentrations of zymosan A higher than 5 microg/ml were also effective in activating microglia but significantly decreased the number of viable cells. In summary, microglial cells remain in the activated state for several days after the isolation process and, thus, stimulation of microglia recently isolated can compromise interpretation of the results. However, upon 13 DIV, cells achieve properties of nonactivated microglia and present a characteristic response to a proinflammatory agent.

Regulation of catecholamine release and tyrosine hydroxylase in human adrenal chromaffin cells by interleukin-1beta: role of neuropeptide Y and nitric oxide.

Adrenal chromaffin cells synthesize and secrete catecholamines and neuropeptides that may regulate hormonal and paracrine signaling in stress and also during inflammation. The aim of our work was to study the role of the cytokine interleukin-1beta (IL-1beta) on catecholamine release and synthesis from primary cell cultures of human adrenal chromaffin cells. The effect of IL-1beta on neuropeptide Y (NPY) release and the intracellular pathways involved in catecholamine release evoked by IL-1beta and NPY were also investigated. We observed that IL-1beta increases the release of NPY, norepinephrine (NE), and epinephrine (EP) from human chromaffin cells. Moreover, the immunoneutralization of released NPY inhibits catecholamine release evoked by IL-1beta. Moreover, IL-1beta regulates catecholamine synthesis as the inhibition of tyrosine hydroxylase decreases IL-1beta-evoked catecholamine release and the cytokine induces tyrosine hydroxylase Ser40 phosphorylation. Moreover, IL-1beta induces catecholamine release by a mitogen-activated protein kinase (MAPK)-dependent mechanism, and by nitric oxide synthase activation. Furthermore, MAPK, protein kinase C (PKC), protein kinase A (PKA), and nitric oxide (NO) production are involved in catecholamine release evoked by NPY. Using human chromaffin cells, our data suggest that IL-1beta, NPY, and nitric oxide (NO) may contribute to a regulatory loop between the immune and the adrenal systems, and this is relevant in pathological conditions such as infection, trauma, stress, or in hypertension.

Cardosins improve neuronal regeneration after cell disruption: a comparative expression study.

The establishment of primary cell cultures is invaluable for studying cell and molecular biological questions. Although primary cell cultures more closely resemble and function like in the native environment, during the culture establishment the cells undergo several changes including the damage sustained during their removal from original tissue. The resultant cells have to rebalance the expression of their processing molecules to ascertain matrix signalling that ensure cell adaptation and consequent proliferation. Hence, we used cardosin, a novel plant enzyme for tissue disaggregation, for isolating and culturing neuronal cells from embryonic rats. The present investigation reports the molecular events, mainly related with matrix metalloproteinases (MMPs)/tissue inhibitor of metalloproteinase (TIMPs) expression, which could substantiate the superior neurite outgrowth and dendritic extension previously described. It was observed that 24 h after primary culture establishment, MMP-2 and MMP-9 messenger RNA (mRNA) are significantly upregulated, while the expression of TIMP-1 and TIMP-2 is unaltered. Regarding the role of laminin in neuronal pathfinding, it was found that the use of anti-laminin antibody and arginine-glycine-aspartate (RGD) peptide exerted inhibitory effects on neurite outgrowth after mechanical lesion where the expression of MMP-9 and TIMP-1 is upregulated under non-permissive conditions in response to mechanical injury.

Driving GDNF expression: the green and the red traffic lights.

Glial cell line-derived neurotrophic factor (GDNF) is widely recognized as a potent survival factor for dopaminergic neurons of the nigrostriatal pathway that degenerate in Parkinson's disease (PD). In animal models of PD, GDNF delivery to the striatum or the substantia nigra protects dopaminergic neurons against subsequent toxin-induced injury and rescues previously damaged neurons, promoting recovery of the motor function. Thus, GDNF was proposed as a potential therapy to PD aimed at slowing down, halting or reversing neurodegeneration, an issue addressed in previous reviews. However, the use of GDNF as a therapeutic agent for PD is hampered by the difficulty in delivering it to the brain. Another potential strategy is to stimulate the endogenous expression of GDNF, but in order to do that we need to understand how GDNF expression is regulated. The aim of this review is to do a comprehensive analysis of the state of the art on the control of endogenous GDNF expression in the nervous system, focusing mainly on the nigrostriatal pathway. We address the control of GDNF expression during development, in the adult brain and after injury, and how damaged neurons signal glial cells to up-regulate GDNF. Pharmacological agents or natural molecules that increase GDNF expression and show neuroprotective activity in animal models of PD are reviewed. We also provide an integrated overview of the signalling pathways linking receptors for these molecules to the induction of GDNF gene, which might also become targets for neuroprotective therapies in PD.

Intracellular signaling mechanisms mediating catecholamine release upon activation of NPY Y1 receptors in mouse chromaffin cells.

The adrenal chromaffin cells synthesize and release catecholamine (mostly epinephrine and norepinephrine) and different peptides, such as the neuropeptide Y (NPY). NPY stimulates catecholamine release through NPY Y1 receptor in mouse chromaffin cells. The aim of our study was to determine the intracellular signaling events coupled to NPY Y1 receptor activation that lead to stimulation of catecholamine release from mouse chromaffin cells. The stimulatory effect of NPY mediated by NPY Y1 receptor activation was lost in the absence of extracellular Ca2+. On the other hand, inhibition of nitric oxide synthase and guanylyl cyclase also decreased the stimulatory effect of NPY. Moreover, catecholamine release stimulated by NPY or by the nitric oxide donor (NOC-18) was inhibited by mitogen-activated protein kinase (MAPK) and protein kinase C inhibitors. In summary, in mouse chromaffin cells, NPY evokes catecholamine release by the activation the NPY Y1 receptor, in a Ca2+-dependent manner, by activating mitogen-activated protein kinase and promoting nitric oxide production, which in turn regulates protein kinase C and guanylyl cyclase activation.

Neuropeptide Y regulates catecholamine release evoked by interleukin-1beta in mouse chromaffin cells.

Activation of the hypothalamic-pituitary-adrenal gland (HPA) axis can modulate the immune system. Cytokines and neuropeptide Y (NPY) are potent regulators of the HPA axis and are both produced by the adrenal medulla. The cytokine interleukin-1beta (IL-1beta) belongs to the interleukin-1 family along with interleukin-1alpha and the interleukin receptor antagonist (IL-1ra). The aim of the present study was to determine the interaction between NPY and IL-1beta in catecholamine (norepinephrine, NE and epinephrine, EP) release from mouse chromaffin cells in culture. We found that IL-1beta increased the constitutive release of NPY, NE and EP from mouse chromaffin cells. This IL-1beta stimulatory effect was blocked by IL-1ra. The immunoneutralization of NPY and the use of the NPY Y(1) receptor antagonist (BIBP 3226) inhibited the stimulatory effect of IL-1beta on catecholamine release from these cells. The present work shows that IL-1beta induces catecholamine release, and in turn this peptide will induce an additional increase in catecholamine release acting through the Y(1) receptor. This work suggests that NPY is involved in the regulatory loop between the immune and the adrenal system in some pathophysiological conditions where plasmatic IL-1beta increases, like in sepsis, rheumatoid arthritis, stress or hypertension.

Interleukin-1beta mediates GDNF up-regulation upon dopaminergic injury in ventral midbrain cell cultures.

We recently proposed the involvement of diffusible modulators in signalling astrocytes to increase glial cell line-derived neurotrophic factor (GDNF) expression after selective dopaminergic injury by H2O2 or L-DOPA. Here we report that interleukin-1beta (IL-1beta) is involved in this crosstalk between injured neurons and astrocytes. IL-1beta was detected only in the media from challenged neuron-glia cultures. Exogenous IL-1beta did not change GDNF protein levels in astrocyte cultures, and diminished GDNF levels in neuron-glia cultures. This decrease was not due to cell loss, as assessed by the MTT assay and immunocytochemistry. Neither H2O2 nor L-DOPA induced microglia proliferation or appeared to change its activation state. The IL-1 receptor antagonist (IL-1ra) prevented GDNF up-regulation in challenged cultures, showing that IL-1beta is involved in the signalling between injured neurons and astrocytes. Since IL-1ra decreased the number of dopaminergic neurons in H2O2-treated cultures, we propose that IL-1 has a neuroprotective role in this system involving GDNF up-regulation.

Selective injury to dopaminergic neurons up-regulates GDNF in substantia nigra postnatal cell cultures: role of neuron-glia crosstalk.

The effect of selective injury to dopaminergic neurons on the expression of glial cell line-derived neurotrophic factor (GDNF) was examined in substantia nigra cell cultures. H(2)O(2), mimicking increased oxidative stress, or l-DOPA, the main symptomatic treatment for Parkinson's disease, increased GDNF mRNA and protein levels in a time-dependent mode in neuron-glia mixed cultures. The concentration dependence indicated that mild, but not extensive, injury induced GDNF up-regulation. GDNF neutralization with an antibody decreased dopaminergic cell viability in H(2)O(2)-treated cultures, showing that up-regulation of GDNF was protecting dopaminergic neurons. Neither H(2)O(2) nor l-DOPA directly affected GDNF expression in astrocyte cultures, but conditioned media from challenged mixed cultures increased GDNF mRNA and protein levels in astrocyte cultures, indicating that GDNF up-regulation was mediated by neuronal factors. Since pretreatment with 6-OHDA completely abolished H(2)O(2)-induced GDNF up-regulation, we propose that GDNF up-regulation is triggered by failing dopaminergic neurons that signal astrocytes to increase GDNF expression.

GDNF modulates HO-1 expression in substantia nigra postnatal cell cultures.

Heme oxygenase-1 (HO-1) has been strongly highlighted because of its induction in many cell types by toxic stimuli, including oxidative stress. The intense HO-1 immunostaining in the substantia nigra of Parkinson disease (PD) patients suggests its involvement in the pathogenesis of this neurodegenerative disease. In this work we investigated HO-1 expression in rat substantia nigra postnatal cell cultures under conditions mimicking dopamine toxicity and its modulation by glial cell line-derived neurotrophic factor (GDNF), a potent neuroprotective factor for dopaminergic neurons. In neuron-glia cultures, we found that H2O2, a product of dopamine metabolism, or l-3,4-dihydroxyphenylalanine (L-DOPA), the dopamine precursor used in the therapy of PD, induced a fast up-regulation of HO-1 mRNA and protein levels, followed by a secondary down-regulation. H2O2 and L-DOPA also increased HO-1 expression in astrocyte cultures, but with a delayed time course in H2O2-treated cultures. HO-1 expression was decreased in neuron-glia cultures under conditions under which GDNF up-regulation was observed. Because exogenously applied GDNF prevented HO-1 up-regulation in cultures treated with H2O2 or l-DOPA, and antibody neutralization of GDNF prevented the secondary HO-1 down-regulation observed in neuron-glia cultures, we propose that GDNF negatively modulates HO-1 expression induced by oxidative stress. To our knowledge, this is the first report showing the modulation of HO-1 expression by GDNF.

Differential expression of syntaxin 1A and 1B by noradrenergic and adrenergic chromaffin cells.

The expression and localization of syntaxin isoforms 1A and 1B in adrenergic and noradrenergic chromaffin cells were examined by both immunoblot analysis and confocal immunofluorescence microscopy. Syntaxin 1A was found in higher levels in noradrenergic cells, whereas syntaxin 1B was similarly expressed in most noradrenergic and adrenergic cells. However, some heterogeneity was observed within each catecholaminergic phenotype. Although the majority of adrenergic cells appeared to express low levels of syntaxin 1A, about 7% was strongly stained for syntaxin 1A. A subpopulation of noradrenergic cells, about 17%, expressed greater levels of syntaxin 1B. Syntaxin 1B labeling showed a punctate appearance in the cytoplasm, whereas syntaxin 1A appeared predominantly localized to the plasma membrane. These data show differences in the exocytotic machinery of the two subtypes of chromaffin cells that may underlie some of the distinct characteristics of adrenaline and noradrenaline secretion.