864 resultados para Circadian Rhythm


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Análise das relações existentes entre as predições dos modelos fonológicos não-lineares (em especial, o de Hayes, 1995) a respeito da quantidade das sílabas e a efetiva realização fonética dessas sílabas em termos de duração, através da consideração de dados extraídos do Projeto Gramática do Português Falado.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Os anestésicos inalatórios sensibilizam o miocárdio ou seu sistema de condução à ação das catecolaminas endógenas e/ou exógenas, predispondo o animal às arritmias cardíacas. Dentre os anestésicos voláteis, o sevoflurano e o desflurano são fármacos relativamente recentes e, embora sejam dotados de características relacionadas a não sensibilização do miocárdio às catecolaminas, desconhecem-se estudos que comparem suas eventuais propriedades antiarritmogênicas. Com o objetivo de estudar, comparativamente, o comportamento do ritmo cardíaco e observar eventuais bloqueios atrioventriculares em cães anestesiados pelo sevoflurano e desflurano e submetidos à infusão contínua de adrenalina, foram utilizados 20 animais adultos, os quais foram separados em dois grupos de igual número (G1 e G2). Aos cães do G1, foi administrado propofol, na dose média de 10mmg.kg-1; em seguida os animais receberam sevoflurano, a 1,5CAM. Decorridos 30 minutos do início da administração do anestésico volátil, iniciou-se a infusão de adrenalina na dose de 1mmg.kg-1.min-1. A cada 10 minutos, a dose da catecolamina foi acrescida em uma unidade, cessando-se a administração em 6mmg.kg-1.min-1. Para o G2, empregou-se a mesma metodologia, substituindo-se o sevoflurano pelo desflurano, administrado a 1,5CAM. A cada dose de adrenalina, foi feita contagem de batimentos ventriculares ectópicos, bem como a observação de bloqueios atrioventriculares. Os achados foram tratados pelos métodos estatísticos de Análise de Perfil e Kruskall-Wallis. Os resultados permitiram concluir que o desflurano minimiza de maneira mais eficiente a arritmia induzida pela adrenalina, além de reduzir a incidência de bloqueios atrioventriculares.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In the present investigation the locomotor and the metabolic activity of Gymnostreptus olivaceus were studied, using 24-hr cycles at different photoperiods and constant temperature and RH. Locomotor activity was studied by the actography method and was reported as coefficients of nocturnalism [CN (N/N + D). 100]. The results showed a nocturnalism coefficient of 98,71% under normal photoperiod conditions and of 29,58% under inverted photoperiod conditions. In constant illumination, the CN of G. olivaceus was 88,22%, and in constant darkness, its rhythm was close to that of the normal photoperiod (CN = 94,92%). The metabolic activity was studied by manometric Warburg respirometry and lit was reported as mu l O-2 . g(-1). h(-1). The respiratory rate of G. olivaceus under normal photoperiod condition was higher at night than during the day (52,52 x 28,76), coinciding with the pattern of nocturnal locomotor activity of the animal. However, under conditions of inverted photoperiod, the millipede maintained its tendency toward a more intense nocturnal respiratory rate (50,35 x 39,14). Similar behaviours were observed under constant illumination and constant darkness, in which G. olivaceus again presented higher nocturnal respiratory rates than diurnal ones(85,84 x 53,48 and 73,18 x 57,0, respectively). The present experimental data suggests the persistence of an endogenous rhythm where the light may not be an important exogenous synchronizer of the activity of G. olivaceus, because it was insufficient to block the start of the biological clock and the natural tendency of higher nocturnal activities of millipedes, principally when the tests were performed in constant illumination or darkness (free-running tests).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Objective: To study the electroclinical phenotype in 5 patients with large Supernumerary marker chromosome referred as inv dup (15), in an attempt to analyze the electroclinical spectrum in order to determine if the binomial epilepsy-EEG is stereotyped enough to corroborate this challenging diagnosis.Methods: Five patients with large inv dup (15) were submitted to EEG and/or V-EEG, with a minimum duration of 2 h. Two certified neurophysiologists analyzed all EEG tracings simultaneously, blinded to clinical and molecular data. Epilepsy was characterized by detailed history and a standard questionnaire according to International League Against Epilepsy guidelines and corroborated by V-EEG findings.Results: Epilepsy started during infancy in 4 patients, in 3 with spasms. Spasms were easily controlled in one but not in others. Epilepsy evolved with generalized seizures in two patients and, generalized and focal in one. Currently, 3 patients present refractory epilepsy and two are seizure-free. In one patient, only one isolated episode suggestive of a secondary generalized tonic-clonic event occurred at the age of 12 years without recurrence. Regarding the EEG, patients had distinct features, except for two patients with very high amplitude fast activity, resembling recruiting rhythm. Despite good seizure outcome in 3 patients, EEGs remained remarkably abnormal with frequent epileptiform discharges over poorly organized background.Conclusions: Our data showed a heterogeneous electroclinical phenotype with generalized and partial epilepsy, presenting distinct degrees of severity and refractoriness.Significance: Our findings suggest that it is not possible to delineate an electroclinical phenotype in this neurogenetic syndrome. Therefore, inv dup (15) remains as a diagnostic challenge and epilepsy and EEG features are valuable only when inserted in the proper clinical context. (c) 2006 International Federation of Clinical Neurophysiology. Published by Elsevier B.V.. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We examined the relationship between fungal refuse production and vegetation input in a laboratory colony of the leaf-cutting ant Acromyrmex coronatus. We found only a strong 6-day time-delay in the production of refuse with variation in substrate intake.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The primary role of the respiratory system is to ensure adequate tissue oxygenation, eliminate carbon dioxide and help to regulate acid-base status. To maintain this homeostasis, amphibians possess an array of receptors located at peripheral and central chemoreceptive sites that sense respiration-related variables in both internal and external environments. As in mammals, input from these receptors is integrated at central rhythmogenic and pattern-forming elements in the medulla in a manner that meets the demands determined by the environment within the constraints of the behavior and breathing pattern of the animal. Also as in mammals, while outputs from areas in the midbrain may modulate respiration directly, they do not play a significant role in the production of the normal respiratory rhythm. However, despite these similarities, the breathing patterns of the two classes are different: mammals maintain homeostasis of arterial blood gases through rhythmic and continuous breathing, whereas amphibians display an intermittent pattern of aerial respiration. While the latter is also often rhythmic, it allows a degree of fluctuation in key respiratory variables that has led some to suggest that control is not as tight in these animals. In this review we will focus specifically on recent advances in studies of the control of ventilation in anuran amphibians. This is the group of amphibians that has attracted the most recent attention from respiratory physiologists. (c) 2006 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The changes of arterial pressure promoted by bolus injection of 50 mg phenylephrine (PHE) were studied in 20 atropinized patients (5 normal subjects, 13 patients with mitral valve disease, 1 patient with essential arterial hypertension and 1 patient with hypertrophic cardiomyopathy) submitted to routine catheterism. Patients with aortic valve disease, left ventricular outflow tract obstruction and intracardiac shunt were excluded from the study. All patients were in sinus rhythm, without heart failure. Arterial pressure started to increase at 14.8 +/- 5.4 s (range, 5.6 to 27 s; mean +/- SD) after PHE. There was an increase of 37.8 +/- 16.7 mmHg (range, 12.5 to 70 mmHg) in systolic pressure and of 26.6 +/- 11.1 mmHg (range, 7.5 to 42.5 mmHg) in diastolic pressure. Peak hypertension was attained at 36.6 +/- 16.4 s (range, 10.8 to 64.9 s) and hypertension continued for 176 +/- 92 s (range, 11 to 365 s). Heart rate was 114 +/- 21 bpm before PHE and 111 +/- 21 bpm (P<0.05) after PHE. There were no adverse events associated with intravenous PHE injection in any patient, in accordance with the general view that bolus injection of PHE is a safe and practical maneuver to promote arterial hypertension.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Adolescents usually exhibit late sleep phase and irregular sleep patterns. As a result, they do not get enough sleep and report daytime sleepiness. This condition could be aggravated in working students who have a more limited time for sleep. In this survey, we investigated the impact of evening classes and employment on the sleep patterns of adolescents. We compared female (n = 17) and male (n = 14) non-worker students to female (n = 28) and male (n = 20) worker students who attended the same high school. The volunteers (aged 17.4 years +/- 11 months) answered a sleep log during a 16-day period. Worker students slept and woke up earlier, had a shorter nocturnal sleep length and a shorter daily (nocturnal plus diurnal) sleep length compared to non-working pupils. The four groups of students delayed sleep onset time on weekends, but only worker students delayed wake-up time on Sundays. The wake-up time was similar among groups on Sundays. While student workers tended to increase the sleep length in the weekends, non-working students increased it on Mondays and/or Tuesdays. The results showed that sleep schedules and sleep length were different according to the work status. Going to bed later on Saturday by the four groups of students suggests the influence of social activities, while a later wake-up time on Sundays could result from a shorter sleep length on workdays.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The electrocardiographic effects of dobutamine stress testing (10 to 40 mu g/kg/minute) were investigated in five conscious healthy dogs. We studied the changes in the duration and amplitude of P wave, PR interval, duration of QRS complex, R wave amplitude, QT interval, and heart rate. Development of arrhythmias and ST segment abnormalities were also recorded. It was observed that dobutamine significantly affects atrioventricular-nodal conduction and total electrical systole time at higher infusion rates. Only a single episode of sustained ventricular tachycardia was observed, which was promptly restored to sinus rhythm shortly after dobutamine infusion was discontinued. No ST segment abnormalities were detected. Dobutamine stress testing was concluded to play a role in some ECG parameters at higher infusion rates.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The current rhythm of petroliferous exploration is esteem that the existing reserves will be depleted in next the 45 years. Thus being, it has that to study intensely, what it has come to be fact, the alternative power plants, as well as the technologies economically capable to ultilizar them. The potential demand of biodiesel for 2020 is taken in consideration that, in accordance with the International Agency of Energia (AIE), in only eight countries, will jump of 34,7 million tons in 2010 for 133,8 million in 2020, with an increment next to 300%. The tame nut is a producing oil plant with all the qualities necessary to be transformed into oil diesel. Beyond perennial and of easy culture, it presents good conservation of the harvested seed, being able to become great producer of substance cousin as optional fuel source. For these authors, this is a culture that can be developed in the small properties, with the available familiar man power, being plus a source of income for the country properties of the Northeast Region. The objective of this work is to evidence the capacity of oil production of the nut-bellwether, and the quality of extration with hexano and methanol in 6 distinct times.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fish control the relative flow rates of water and blood over the gills in order to optimise respiratory gas exchange. As both flows are markedly pulsatile, close beat-to-beat relationships can be predicted. Cardiorespiratory interactions in fish are controlled primarily by activity in the parasympathetic nervous system that has its origin in cardiac vagal. preganglionic neurons. Recordings of efferent activity in the cardiac vagus include units firing in respiration-related bursts. Bursts of electrical stimuli delivered peripherally to the cardiac vagus or centrally to respiratory branches of cranial, nerves can recruit the heart over a range of frequencies. So, phasic, efferent activity in cardiac vagi, that in the intact fish are respiration-related, can cause heart rate to be modulated by the respiratory rhythm. In elasmobranch fishes this phasic activity seems to arise primarily from central feed-forward interactions with respiratory motor neurones that have overlapping distributions with cardiac neurons in the brainstem. In teleost fish, they arise from increased levels of efferent vagal activity arising from reflex stimulation of chemoreceptors and mechanoreceptors in the orobranchial, cavity. However, these differences are largely a matter of emphasis as both groups show elements of feed-forward and feed-back control of cardiorespiratory interactions. (C) 2008 Elsevier GmbH. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

From field observations on Drimys brasiliensis, principally in the Botucatu region of São Paulo State, Brazil, new data on the reproductive biology, the rhythm of growth, and the development of lateral cymose inflorescences, flowers and fruits are presented. Pollination accelerates the rate of flower-development for about 4-6 days. Pollination experiments show that D. brasiliensis is not self-sterile; because of mechanical devices the sticky pollen grains do not normally come into contact with the stigmata unless an animal pollen vector is involved. The pollinators are diurnal Coleoptera, Diptera and Thysanoptera which eat from the pollen, lick from the stigmatic exudates and (in case of the flies) probably also from the staminal glands. Fruit- and seedeaters are birds which seem to be the main dispersal agents. Establishment of new individuals normally is through seedlings, but also by vegetative propagation through plagiotropous branches which may root and separate from the mother plant. The morphological, developmental and reproductive aspects in D. brasiliensis are discussed in a wider context, compared with data from other Magnoliidae, and related to aspects of early Angiosperm evolution. © 1980 Springer-Verlag.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The aim of this study was to test the application and value of electrocorticography (ECG) in the early diagnosis and characterization of electrocorticograms changes on experimental fulminant hepatic failure (FHF). Our material was composed of two groups of guinea pigs: a) ethanolamine group--42 animals with FHF induced by intrabiliary injection of 2.5 ml of monoethanolamine oleate; b) control group--10 animals submitted to intrabiliary injection of 2.5 ml of saline. Electrocorticograms recordings were taken in both groups with the electrodes implanted on the parieto-occipital regions of the skull. The hepatic failure was characterized by clinical manifestations, serum biochemical tests and histopathological findings. In the early hepatic coma the electrocorticograms could not be unequivocally distinguished from normal pattern, and alpha rhythm was recognizable in most animals. With further deterioration of the clinical condition the tracing showed progressive slowness of the normal rhythm, increased voltage and triphasic waves followed by suppression of electrical activity preceding the animal death. The electrocorticography was not suitable for the early diagnosis of hepatic coma, since the ECG alterations became evident only in overt coma. However the method could be useful for the characterization of cerebral disorders and the study of the pathogenesis of fulminant hepatic failure.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We examined the EEG of 88 patients with chronic renal failure (80 adults and 8 children) submitted to different types of treatment such as hemodialysis, peritoneal dialisys, renal transplantation, and ambulatory follow-up. The main alteration observed was diffuse disorganization of background activity. The following features were detected in decreasing order of frequency: low-voltage EEG, triphasic waves, abnormal waking reactions, and paradoxal alpha rhythm. The children showed abnormal alpha rhythm. The alterations induced by intermittent photic stimulation in our patients were minimal, and this was the main difference in relation to data reported by other authors in EEG studies on patients with chronic uremia.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Further knowledge of feline physiology and neonatology is needed because the number of cats being kept as pets and used as experimental animals has increased. Few studies have been published on feline sequential electrocardiography. This study was conducted to determine the values of normal waves, complexes, and intervals of the electrocardiogram in clinically healthy feline neonates. Serial electrocardiography was performed in 15 female and 15 male neonates at 30 days of age. Parameters analyzed were heart rate and rhythm, duration and amplitude of electrocardiographic waves, duration of intervals, and the electrical axis of the heart. The results did not show differences between males and females. During the neonates' first 30 days of life, migration of the electrical axis from right to left was observed. There was a progressive increase in the R wave amplitude, while the S wave amplitude showed a progressive decrease. A sinus heart rhythm was predominant in the feline neonates.