Sample records for oscillations plasma
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Sample records 1 - 5 shown.



1

La desincronización interna como promotora de enfermedad y problemas de conducta/ Internal desynchrony as promotor of disease and behavioral disturbance

Salgado Delgado, Roberto Carlos; Fuentes Pardo, Beatriz; Escobar Briones, Carolina
2009-02-01

Resumen en español La vida se rige por una estructura temporal que gobierna nuestras horas, nuestros días y nuestros calendarios. Como parte de la adaptación a los ciclos de tiempo que impone el planeta, todo organismo presenta ritmos en su actividad y fisiología. Los ritmos biológicos son una propiedad conservada en todos los niveles de organización, desde organismos unicelulares procariontes hasta plantas superiores y mamíferos. De ellos, los más sólidos son aquellos asociados a l (mas) os ciclos externos por la alternancia del día y la noche y por la alternancia de las estaciones del año. Los ritmos biológicos fisiológicos y conductuales son procesos dependientes de un reloj interno capaz de ajustar sus oscilaciones a claves de tiempo externas que lo mantienen sincronizado a estas fluctuaciones externas. El núcleo supraquiasmático del hipotálamo (NSQ) es en los mamíferos el principal reloj circadiano y se sincroniza principalmente por el ciclo luz-oscuridad. El NSQ transmite señales de tiempo al cerebro y de ahí al resto del organismo, y por medio de estas señales de tiempo mantiene un orden temporal en diversas funciones del cuerpo y las mantiene ajustadas al ciclo luz-oscuridad. El correcto orden temporal interno permite un adecuado funcionamiento del individuo en armonía con el medio externo y le permite exhibir respuestas adecuadas a un ambiente cambiante y predecible. El estilo de vida del hombre moderno propicia situaciones que llevan a alteraciones de nuestros ritmos biológicos que causan una desadaptación temporal, que a su vez redunda en daños a la salud, ya que afecta tanto la fisiología como la forma en que organizamos nuestra conducta. Un ejemplo de ello son los viajes a través de múltiples regiones horarias. Estos cambios de horario bruscos provocan un síndrome conocido como jet-lag, que consiste en un conflicto transitorio entre el tiempo > y el tiempo >, lo cual se denomina >. El jet-lag se define como un conjunto de síntomas causados por una alteración del patrón de sueño, y de la expresión de ritmos biológicos fuera de fase entre sí y fuera de fase con el ciclo del día y la noche. Esta es la causa del malestar general, el deterioro del desempeño mental y físico, así como de la irritabilidad y depresión. Son frecuentes también las alteraciones gastrointestinales, resultado del consumo de alimento en un horario inusual. Otro ejemplo de alteraciones en los ritmos circadianos se observa en los trabajadores con turnos rotatorios o en turnos nocturnos. En estas condiciones se produce un conflicto entre las señales temporales asociadas al ciclo diurno y que transmite el reloj con las actividades y alimentos del trabajador en turnos. De este esquema de trabajo resulta una reducción de las horas de sueño y una alteración de los ritmos circadianos, que llevan a una desincronización interna. Ésta, al igual que en el caso del jet-lag, redunda en un deterioro de las funciones mentales y de la capacidad de atención y memorización, que se asocian a irritabilidad y problemas emocionales. Además, se observan consecuencias en la salud con incremento en la incidencia de malestares gastrointestinales, enfermedades cardiovasculares, obesidad y diabetes. La mejoría en los servicios de salud ha incrementado las expectativas de vida, lo que entonces enfrenta a la humanidad a una población que logra sobrevivir muchos años de su vejez con los cambios de conducta y salud propios de su edad, entre los que se incluye un deterioro de los ritmos biológicos. En este trabajo presentamos una revisión de las principales alteraciones de los ritmos biológicos generadas por los viajes transmeridionales, la vejez y el trabajo en turnos. También discutimos la relevancia de una buena adaptación de los ritmos biológicos y las consecuencias conductuales y fisiológicas que por su alteración llevan a la enfermedad y a un desempeño mental deficiente. También sugerimos estrategias que necesitan ser exploradas y que podrían ayudar prevenir la desincronización interna para mejorar la calidad de vida. Resumen en inglés Life on our planet is ruled by a temporary structure that governs our activities, our days and our calendars. In order to cope with a daily changing environment, organisms have developed adaptive strategies by exhibiting daily behavioral and physiological changes. Biological rhythms are properties conserved in all the levels of organization, from unicellular to prokaryotes to upper plants and mammals. A biological rhythm is defined as the recurrence of a biological phenom (mas) enon in regular intervals of time. Biological rhythms in behaviour and physiology are controled by an internal clock which synchronizes its oscillations to external time cues that have the capacity to adjust the clock's mechanism and keep it coupled to external fluctuations. The suprachiasmatic nucleus (SCN) of the hypothalamus in mammals is the master circadian clock which is mainly entrained by the light-dark cycle. The SCN transmits time signals to the brain and then to the whole body and by means of its time signals the SCN keeps a temporal order in diverse oscillations of the body and adjusted to the light-dark cycle. The correct temporal order enables an individual to adequate functioning in harmony with the external cycles. Biological rhythms have a hereditary character, thus its expression is genetically determined. All animals, plants, and probably all organism show some type of physiological rhythmic variation (metabolic rate, production of heat, flowering, etc.) that allow for the adaptation to a rhythmic environment. Biological rhythms enable individuals to anticipate and to be prepared to the demands of the prominent cyclic environmental changes, which are necessary for survival. Also, biological rhythms promote showing maximum levels of a physiological variable at the right moment when the environment requires a maximal response. In humans, an example of circadian rhythms is the sleep-wake cycle; simultaneously, a series of physiological changes are exhibited, also with circadian characteristics (close to 24 hours). Circadian oscillations are observed in the liberation of luteinizant hormone, in plasma cortisol, leptin, insulin, glucose and growth hormone just to mentions some examples. The SCN controls circadian rhythmicity via projections to the autonomic system and by controlling the hypothalamus-adenohipofisis-adrenal axis. In this way, the SCN transmits phase and period to the peripheral oscillators to maintain an internal synchrony. Modern life favors situations that oppose the time signals in the environment and promote conflicting signals to the SCN and its effectors. The consequence is that circadian oscillators uncouple from the master clock and from the external cycles leading to oscillations out of synchrony with the environment, which is known as internal desynchronization. The consequence is that physiological variables reach their peak expression at wrong moments according to environmental demands leading then to deficient responses and to disease in the long run. Also, levels of attention, learning and memory reach peak expression at wrong moments of the day leading individuals to exhibit a deficient performance at school or work. The disturbed sleep patterns promote fatigue and irritability, which difficult social interaction. Internal desynchronization results from transmeridional traveling for which people pass multiple hourly regions. This results in an abrupt change in the time schedule and a syndrome known as >. Frequent travelers complain about difficulties to adjust their sleep-wake cycle to the new schedule, thus resulting in fatigue, increased sleepiness and reduced attention. Jet lag results from a loss of synchrony among biological rhythms and among diverse functions, which remain out of phase with the day-night cycle. This > is the cause of general discomfort, decrement in the physical and mental performance, as well as irritability and depression. Frequently, gastrointestinal disorders are a by-product of food consumption at an unusual schedule. The state of internal desynchrony is transitory and depends on the number of time zones that were crossed; thus, adaptation to a new external cycle can take from four to seven days. Another example of internal desynchrony is observed in individuals exposed to work shifts or to nocturnal work schedules (night work). In such conditions, circadian fluctuations in behavioral, hormonal and metabolic parameters are observed but their temporary relation with the external cycles is modified. The internal synchrony is thus affected by troubled environmental signs, out of phase with the daily activities of the individual; among them are the hours of food intake, the exposure to light during resting hours, the low temperature of the night, and the forced activity when homeostatic processes indicate a need to rest. This internal desynchrony leads to gastrointestinal disorders, disturbed metabolic fluctuations, disturbed cardiovascular functions, altered menstrual cycle, sleep disorders, sleepiness, increase of work accidents, etc. Internal desynchrony is especially due to the fact that circadian fluctuations are influenced by daily external cycles, but also by homeostatic factors, and can suffer from additional disturbance by sleep deprivation. Despite years of night work experience, incapacity to adapt to night work may persist. Only a minority of shift workers achieve spontaneous adjustment of the rhythms of core body temperature, melatonin, cortisol, thyroid stimulating hormone, or prolactin secretion to shifts by nocturnal work. Therefore shift and night workers develop a propensity to smoke, drink alcoholic beverages and use stimulant products. After five years of shift or night work, health problems appear with a higher incidence than in the general population. The growing social demand of shift work makes it necessary to decide on the characteristics and forms of shifts to carry out, and up to now organizing such working schedules remaing a serious problem. The improvement of health services has increased life expectancies and thus the general population is becoming old and people survive more years. Older people ail from health and behavioral problems including a deterioration of the biological rhythms. Main alterations consist of a loss of expression of the circadian functions or a decrease of the amplitude of the rhythms, and instability of synchronization mechanisms day by day. All in all, this implies a decreased capacity of the clock to adjust to the solar day. The decreased efficacy of the aging biological clock is evident in the fragmented sleep patterns and the disturbed sleep/wake rhythms, characterized by short sleep episodes during the day and decreased sleep during the night. Some studies suggest that the disturbed circadian rhythms may be the cause of diverse diseases associated with the elderly. In conclusion, during the last 100 years we have changed our lifestyle so radically that we lack already a physiological design to adapt so quickly to modernity. We can state that our body is designed for a world that does not exist. In this article we present a review of the main alterations of the biological rhythms generated by the transmeridional trips, shift-work and aging, their behavioral and physiological consequences that lead to disease and poor mental performance. We also discuss possible strategies that need to be explored and that may help people to improve their quality of life and to prevent internal desynchrony.

Scientific Electronic Library Online (Spanish)

2

Residues of Correlators in the Strongly Coupled N=4 Plasma

Amado, Irene; Hoyos, Carlos; Landsteiner, Karl; Montero, Sergio
2008-02-28

Digital.CSIC (Spain)

3

Relic Density of Neutrinos with Primordial Asymmetries

Pastor, Sergio; Pinto Cejas, Teguayco; Raffelt, G.G.
2009-06-19

Digital.CSIC (Spain)

4

Hydrodynamics and beyond in the strongly coupled N=4 plasma

Amado, Irene; Hoyos, Carlos; Landsteiner, Karl; Montero, Sergio
2008-05-16

Digital.CSIC (Spain)

5

Efecto de enzimas proteolíticas y de la abstinencia sexual en la cuantificación bioquímica de alfa-glucosidasa en plasma seminal humano/ Effects of proteolytic enzymes and sexual abstinence on alpha-glucosidase levels in human seminal plasma

Peña S, Patricio; Sánchez G, Raúl; Vásquez P, Bélgica; Castillo K, Claudia; Miska, Werner
2001-05-01

Resumen en inglés Background: alpha-glucosidase is found in human seminal plasma as an acid form, located in accessory glands, and as a neutral form secreted almost exclusively by the epididymis. Quantification of alpha-glucosidase activity is a marker of the secretory function of the epididymis and indemnity of the sperm transport pathway Aim: To obtain reference values for alpha-glucosidase in normal samples of seminal plasma, to evaluate its behavior in serial samples and to determine t (mas) he effect of proteolytic enzymes. Material and methods: Fifty donors, with normal semen analysis according to the criteria of the World Health Organization, were evaluated. For the study with alpha-quimotrypsin, 0.1 to 10 mg/ml of the enzyme was added to the seminal plasma from a group of donors. alpha-glucosidase was also measured in semen obtained from nine patients at different time intervals. Results: Normal alpha-glucosidase values ranged from 14.52 to 25.69 µU/ml. Concentrations up to 10 mg/ml of alpha-quimotrypsin (10 times of that usually used in the liquefaction of the semen) did not alter the quantification of alpha-glucosidase. Serial determinations revealed oscillations in their magnitude, which stayed in each patient's characteristic range. However a subgroup presented a marked reduction of the activity of a-glucosidase as the abstinence diminished (40%). Conclusions: Evaluation of alpha-glucosidase in seminal plasma gives reliable information of the secretor state of the epididymis and especially replaces invasive methods used to evaluate the indemnity of the spermatic transport from the epididymis to the anterior urethra. (Rev Méd Chile 2001; 129: 489-93)

Scientific Electronic Library Online (Spanish)