Contribution of cholinergic systems to state-dependent modulation of respiratory control

Respiration is altered during different stages of the sleep-wake cycle. We review the contribution of cholinergic systems to this alteration, with particular reference to the role of muscarinic acetylcholine receptors (MAchRs) during rapid eye movement (REM) sleep. Available evidence demonstrates that MAchRs have potent excitatory effects on medullary respiratory neurones and respiratory motoneurones, and are likely to contribute to changes in central chemosensitive drive to the respiratory control system. These effects are likely to be most prominent during REM sleep, when cholinergic brainstem neurones show peak activity levels. It is possible that MAchR dysfunction is involved in sleep-disordered breathing, Such as obstructive sleep apnea. (C) 2002 Elsevier Science B.V. All rights reserved.

The distribution and morphological characteristics of catecholaminergic cells in the brain of monotremes as revealed by tyrosine hydroxylase immunohistochemistry

The present study describes the distribution and cellular morphology of catecholaminergic neurons in the CNS of two species of monotreme, the platypus (Ornithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus). Tyrosine hydroxylase immunohistochemistry was used to visualize these neurons. The standard A1-A17, C1-C3 nomenclature was used for expediency, but the neuroanatomical names of the various nuclei have also been given. Monotremes exhibit catecholaminergic neurons in the diencephalon (All, A12, A13, A14, A15), midbrain (A8, A9, A10), rostral rhombencephalon (A5, A6, A7), and medulla (A1, A2, C1, C2). The subdivisions of these neurons are in general agreement with those of other mammals, and indeed other amniotes. Apart from minor differences, those being a lack of A4, A3, and C3 groups, the catecholaminergic system of monotremes is very similar to that of other mammals. Catecholaminergic neurons outside these nuclei, such as those reported for other mammals, were not numerous with occasional cells observed in the striatum. It seems unlikely that differences in the sleep phenomenology of monotremes, as compared to other mammals, can be explained by these differences. The similarity of this system across mammalian and amniote species underlines the evolutionary conservatism of the catecholaminergic system. Copyright (C) 2002 S. Karger AG, Basel.

The distribution and morphological characteristics of serotonergic cells in the brain of monotremes

The distribution and cellular morphology of serotonergic neurons in the brain of two species of monotremes are described. Three clusters of serotonergic neurons were found: a hypothalamic cluster, a cluster in the rostral brainstem and a cluster in the caudal brainstem. Those in the hypothalamus consisted of two groups, the periventricular hypothalamic organ and the infundibular recess, that were intimately associated with the ependymal wall of the third ventricle. Within the rostral brainstem cluster, three distinct divisions were found: the dorsal raphe nucleus (with four subdivisions), the median raphe nucleus and the cells of the supralemniscal region. The dorsal raphe was within and adjacent to the periaqueductal gray matter, the median raphe was associated with the midline ventral to the dorsal raphe, and the cells of the supralemniscal region were in the tegmentum lateral to the median raphe and ventral to the dorsal raphe. The caudal cluster consisted of three divisions: the raphe obscurus nucleus, the raphe pallidus nucleus and the raphe magnus nucleus. The raphe obscurus nucleus was associated with the dorsal midline at the caudal-most part of the medulla oblongata. The raphe pallidus nucleus was found at the ventral midline of the medulla around the inferior olive. Raphe magnus was associated with the midline of the medulla and was found rostral to both the raphe obscurus and raphe pallidus. The results of our study are compared in an evolutionary context with those reported for other mammals and reptiles. Copyright (C) 2002 S. Karger AG, Basel.

The distribution and morphological characteristics of cholinergic cells in the brain of monotremes as revealed by ChAT immunohistochemistry

The present study employs choline acetyltransferase (ChAT) immunohistochemistry to identify the cholinergic neuronal population in the central nervous system of the monotremes. Two of the three extant species of monotreme were studied: the platypus (Omithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus). The distribution of cholinergic cells in the brain of these two species was virtually identical. Distinct groups of cholinergic cells were observed in the striatum, basal forebrain, habenula, pontomesencephalon, cranial nerve motor nuclei, and spinal cord. In contrast to other tetrapods studied with this technique, we failed to find evidence for cholinergic cells in the hypothalamus, the parabigeminal nucleus (or nucleus isthmus), or the cerebral cortex. The lack of hypothalamic cholinergic neurons creates a hiatus in the continuous antero-posterior aggregation of cholinergic neurons seen in other tetrapods. This hiatus might be functionally related to the phenomenology of monotreme sleep and to the ontogeny of sleep in mammals, as juvenile placental mammals exhibit a similar combination of sleep elements to that found in adult monotremes. Copyright (C) 2002 S. Karger AG, Basel.

Influence of renal denervation on blood pressure, sodium and water excretion in acute total obstructive apnea in rats

Obstructive apnea (OA) can exert significant effects on renal sympathetic nerve activity (RSNA) and hemodynamic parameters. The present study focuses on the modulatory actions of RSNA on OA-induced sodium and water retention. The experiments were performed in renal-denervated rats (D; N = 9), which were compared to sham (S; N = 9) rats. Mean arterial pressure (MAP) and heart rate (HR) were assessed via an intrafemoral catheter. A catheter was inserted into the bladder for urinary measurements. OA episodes were induced via occlusion of the catheter inserted into the trachea. After an equilibration period, OA was induced for 20 s every 2 min and the changes in urine, MAP, HR and RSNA were recorded. Renal denervation did not alter resting MAP (S: 113 ± 4 vs D: 115 ± 4 mmHg) or HR (S: 340 ± 12 vs D: 368 ± 11 bpm). An OA episode resulted in decreased HR and MAP in both groups, but D rats showed exacerbated hypotension and attenuated bradycardia (S: -12 ± 1 mmHg and -16 ± 2 bpm vs D: -16 ± 1 mmHg and 9 ± 2 bpm; P < 0.01). The basal urinary parameters did not change during or after OA in S rats. However, D rats showed significant increases both during and after OA. Renal sympathetic nerve activity in S rats increased (34 ± 9%) during apnea episodes. These results indicate that renal denervation induces elevations of sodium content and urine volume and alters bradycardia and hypotension patterns during total OA in unconscious rats.

Efeito da privação de sono paradoxal e do bloqueio da síntese da corticosterona sobre os limiares da reação de defesa induzida pela estimulação elétrica da matéria cinzenta periaquedutal e colículo superior

O Transtorno do pânico (TP) é um transtorno mental comum que afeta até 5% da população em algum momento da vida, sendo caracterizada pela presença de ataques de pânico (AP) recorrentes. Constitui uma psicopatologia que pode ser afetada pela privação do sono (PS), relação que ainda é pouco compreendida. Neste contexto, modelos experimentais de AP e de PS são ferramentas úteis na investigação dessa possível correlação, especialmente motivado pela crescente condição de privação de sono, que tem se tornado cada vez mais frequente na sociedade moderna. Assim, este estudo avaliou os efeitos da privação de sono paradoxal (PSP) sobre os limiares dos comportamentos defensivos induzidos por estimulação intracraniana (EI) da MCPD e CS de ratos num modelo experimental de AP, assim como verificou a influência da corticosterona sobre esses limiares. Foram utilizados 160 ratos Wistar machos (300g), organizados em 4 grupos com 40 animais cada, como se segue: Grupo Controle (CTR) submetido à EI, porém sem PSP; Grupo Privação (PRV), submetido à EI e privado por 96 horas; Grupo Privação + Bloqueio da corticosterona (PRB), submetido ao tratamento com metirapona, EI, e privado por 96 horas, e Grupo Controle + Bloqueio da corticosterona (CTB), submetido ao tratamento com metirapona e EI, porém sem privação de sono. Após 10 dias do implante cirúrgico intracraniano de eletrodo na MCPD e CS, os animais passaram por 5 sessões de estimulação, como se segue: 1ª (TRI) considerada triagem - imediatamente antes da privação, 2ª (P48) após 48h de privação, 3ª (P96) após 96h de privação, 4ª (R48) após 48h de retirada da privação e 5ª (R96) após 96h de retirada da privação. As curvas de limiares das respostas individuais de defesa obtidas nas várias sessões de estimulação da MCPD e CS (TRI, P48, P96, R48 e R96) dos ratos foram comparadas entre si, bem como as curvas de limiares de uma dada resposta nos diferentes grupos (CTR, PRV, CTB e PRB). Além disso, os níveis de corticosterona (CORT) foram dosados nas diferentes sessões de EI, e comparadas num mesmo grupo, bem como nos diferentes grupos. No grupo CTR, todos os comportamentos foram iguais em todas as sessões quando comparados à TRI, entretanto, nos animais privados (PRV), o limiar do galope (GLP) reduziu significativamente em R48 e R96, não ocorrendo xix alterações nos demais comportamentos. Em contraste, no grupo PRB, o Trote (TRT) aumentou a partir de P48, enquanto o GLP não foi alterado em nenhuma sessão de EI. Na comparação entre os grupos, em Salto (SLT), Micção (MIC), Exoftalmia (EXO), Imobilidade (IMO), Defecação (DEF), TRT e GLP, não sofreram alterações decorrentes da CORT produzida decorrente da PSP, sugerindo que a corticosterona não altera os comportamentos defensivos característicos do Ataque de Pânico. Em adição, tais resultados sugerem que os efeitos tardios da PSP sobre os limiares de GLP possivelmente se devam a mecanismos neuroquímicos tempo-dependente.

Férias, repouso e lazer: direito fundamental constitucional dos trabalhadores

Como nos ensinam os Mestres G. Canotilho e V. Moreira, o direito ao descanso ou repouso e todos os direitos a ele ligados atingem a categoria fundamental de direitos análogos aos direitos, liberdades e garantias: art. 17º CRP. Abstract: As we teach the Masters Canotilho G. and V. Moreira, the right to rest or sleep and all rights attached thereto reach the fundamental category of rights analogous to those rights and freedoms: art. 17 CRP.

Caracterização dos estilos de vida dos sem-abrigo da cidade do Porto

O fenómeno dos sem-abrigo está em constante crescimento nos centros urbanos, na cidade no Porto o mesmo acontece, sendo esta uma realidade ainda pouco conhecida. Têm sido realizados alguns estudos sobre esta problemática, no entanto poucos incidem sobre a população portuguesa, pouco se sabe sobre como vivem estes indivíduos e sobre o que define o seu estilo de vida. Os estilos de vida têm vindo a ser uma área de crescente interesse para estudo, visto que afecta a nossa saúde e a longo prazo tem influência nos padrões de morbilidade e mortalidade. Com este estudo procurou-se caracterizar os sem-abrigo da cidade do Porto e os comportamentos que tipificam o seu estilo de vida, bem como verificar se existem variáveis dos estilos de vida que se encontram correlacionadas com a presença de sintomatologia psicopatológica. Para este efeito, foi realizado um inquérito por questionário a 30 pessoas que vivem na condição de sem-abrigo na cidade do Porto, através da administração de um questionário de estilos de vida e da Brief Psychiatric Rating Scale (BPRS). Concluímos que os sem-abrigo se caracterizam por ser do sexo masculino, solteiros de nacionalidade portuguesa e baixa escolaridade. Constatamos que a maioria apresenta comportamentos pouco saudáveis como fumar e não praticar exercício físico, contudo têm cuidado com a higiene pessoal, apresentam uma boa higiene do sono e manifestam poucos comportamentos sexuais de risco. Verificamos que a ansiedade se encontra correlacionada negativamente com o stress, higiene do sono, insight e alimentação. As perturbações somáticas mostraram uma correlação com a higiene do sono, o humor depressivo com a higiene do sono e insight, o retraimento emocional com a socialização e falta de cooperação com a socialização, sendo todas estas correlações negativas. Encontramos ainda uma correlação positiva entre a lentificação e o consumo de substâncias e uma correlação negativa entre a lentificação e higiene do sono. Considerando os resultados obtidos pensamos ser fundamental prosseguir com estudos de investigação nesta área, para que de futuro as intervenções junto desta população consigam dar uma melhor resposta ao seu estado de saúde.

Working hours, work-life conflict and health in precarious and "permanent" employment

OBJECTIVE: The expansion of precarious employment in OECD countries has been widely associated with negative health and safety effects. Although many shiftworkers are precariously employed, shiftwork research has concentrated on full-time workers in continuing employment. This paper examines the impact of precarious employment on working hours, work-life conflict and health by comparing casual employees to full-time, "permanent" employees working in the same occupations and workplaces. METHODS: Thirty-nine convergent interviews were conducted in two five-star hotels. The participants included 26 full-time and 13 casual (temporary) employees. They ranged in age from 19 to 61 years and included 17 females and 22 males. Working hours ranged from zero to 73 hours per week. RESULTS: Marked differences emerged between the reports of casual and full-time employees about working hours, work-life conflict and health. Casuals were more likely to work highly irregular hours over which they had little control. Their daily and weekly working hours ranged from very long to very short according to organisational requirements. Long working hours, combined with low predictability and control, produced greater disruption to family and social lives and poorer work-life balance for casuals. Uncoordinated hours across multiple jobs exacerbated these problems in some cases. Health-related issues reported to arise from work-life conflict included sleep disturbance, fatigue and disrupted exercise and dietary regimes. CONCLUSIONS:This study identified significant disadvantages of casual employment. In the same hotels, and doing largely the same jobs, casual employees had less desirable and predictable work schedules, greater work-life conflict and more associated health complaints than "permanent" workers.

Effects of the length and timing of nighttime naps on task performance and physiological function

OBJECTIVE: To examine the effects of the length and timing of nighttime naps on performance and physiological functions, an experimental study was carried out under simulated night shift schedules. METHODS: Six students were recruited for this study that was composed of 5 experiments. Each experiment involved 3 consecutive days with one night shift (22:00-8:00) followed by daytime sleep and night sleep. The experiments had 5 conditions in which the length and timing of naps were manipulated: 0:00-1:00 (E60), 0:00-2:00 (E120), 4:00-5:00 (L60), 4:00-6:00 (L120), and no nap (No-nap). During the night shifts, participants underwent performance tests. A questionnaire on subjective fatigue and a critical flicker fusion frequency test were administered after the performance tests. Heart rate variability and rectal temperature were recorded continuously during the experiments. Polysomnography was also recorded during the nap. RESULTS: Sleep latency was shorter and sleep efficiency was higher in the nap in L60 and L120 than that in E60 and E120. Slow wave sleep in the naps in E120 and L120 was longer than that in E60 and L60. The mean reaction time in L60 became longer after the nap, and faster in E60 and E120. Earlier naps serve to counteract the decrement in performance and physiological functions during night shifts. Performance was somewhat improved by taking a 2-hour nap later in the shift, but deteriorated after a one-hour nap. CONCLUSIONS: Naps in the latter half of the night shift were superior to earlier naps in terms of sleep quality. However performance declined after a 1-hour nap taken later in the night shift due to sleep inertia. This study suggests that appropriate timing of a short nap must be carefully considered, such as a 60-min nap during the night shift.

Fatores de risco relacionados à perda de produtividade laboral e aumento dos custos ambulatoriais de pacientes atendidos por unidades básicas de saúde

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Job control, job demands, social support at work and health among adolescent workers

OBJECTIVE: To evaluate physical and psychological dimensions of adolescent labor (such as job demands, job control, and social support in the work environment), and their relation to reported body pain, work injuries, sleep duration and daily working hours. METHODS: A total of 354 adolescents attending evening classes at a public school in São Paulo, Brazil, answered questionnaires regarding their living and working conditions (Karasek's Job Content Questionnaire, 1998), and their health status. Data collection took place in April and May 2001. Multiple logistic regression analysis was used to determine relations among variables. RESULTS: Psychological job demands were related to body pain (OR=3.3), higher risk of work injuries (OR=3.0) and reduced sleep duration in weekdays (Monday to Thursday) (p<0.01). Lower decision authority in the workplace (p=0.03) and higher job security (p=0.02) were related to longer daily working hours. CONCLUSIONS: It was concluded that besides physical stressors, psychological factors are to be taken into account when studying adolescent working conditions, as they may be associated with negative job conditions and health effects.

Qualidade de vida no trabalho em empresa automotiva: comparação entre área administrativa e de produção

Pós-graduação em Engenharia de Produção - FEG

Ensaios geomecânicos em rochas metassedimentares do maciço da Mina das Aveleiras (Mosteiro de Tibães): comparação, potencialidades e limitações

Mestrado em Engenharia Geotécnica e Geoambiente