RESUMEN
Increasing evidence suggests that responsiveness is associated with critical or near-critical cortical dynamics, which exhibit scale-free cascades of spatio-temporal activity. These cascades, or 'avalanches', have been detected at multiple scales, from in vitro and in vivo microcircuits to voltage imaging and brain-wide functional magnetic resonance imaging (fMRI) recordings. Criticality endows the cortex with certain information-processing capacities postulated as necessary for conscious wakefulness, yet it remains unknown how unresponsiveness impacts on the avalanche-like behaviour of large-scale human haemodynamic activity. We observed a scale-free hierarchy of co-activated connected clusters by applying a point-process transformation to fMRI data recorded during wakefulness and non-rapid eye movement (NREM) sleep. Maximum-likelihood estimates revealed a significant effect of sleep stage on the scaling parameters of the cluster size power-law distributions. Post hoc statistical tests showed that differences were maximal between wakefulness and N2 sleep. These results were robust against spatial coarse graining, fitting alternative statistical models and different point-process thresholds, and disappeared upon phase shuffling the fMRI time series. Evoked neural bistabilities preventing arousals during N2 sleep do not suffice to explain these differences, which point towards changes in the intrinsic dynamics of the brain that could be necessary to consolidate a state of deep unresponsiveness.
Asunto(s)
Encéfalo , Circulación Cerebrovascular/fisiología , Electroencefalografía , Hemodinámica/fisiología , Imagen por Resonancia Magnética , Sueño de Onda Lenta/fisiología , Vigilia/fisiología , Encéfalo/irrigación sanguínea , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Femenino , HumanosRESUMEN
The gas phase structure and excited state lifetime of the p-aminophenolp-cresol heterodimer have been investigated by REMPI and LIF spectroscopy with nanosecond laser pulses and pump-probe experiments with picosecond laser pulses as a model system to study the competition between π-π and H-bonding interactions in aromatic dimers. The excitation is a broad and unstructured band. The excited state of the heterodimer is long lived (2.5 ± 0.5) ns with a very broad fluorescence spectrum red-shifted by 4000 cm-1 with respect to the excitation spectrum. Calculations at the MP2/RI-CC2 and DFT-ωB97X-D levels indicate that hydrogen-bonded (HB) and π-stacked isomers are almost isoenergetic in the ground state while in the excited state only the π-stacked isomer exists. This suggests that the HB isomer cannot be excited due to negligible Franck-Condon factors and therefore the excitation spectrum is associated with the π-stacked isomer that reaches vibrationally excited states in the S1 state upon vertical excitation. The excited state structure is an exciplex responsible for the fluorescence of the complex. Finally, a comparison was performed between the π-stacked structure observed for the p-aminophenolp-cresol heterodimer and the HB structure reported for the (p-cresol)2 homodimer indicating that the differences are due to different optical properties (oscillator strengths and Franck-Condon factors) of the isomers of both dimers and not to the interactions involved in the ground state.
RESUMEN
Lifetimes of the first electronic excited state (S(1)) of fluorine and methyl (o-, m-, and p-) substituted phenols and their complexes with one ammonia molecule have been measured for the 0(0) transition and for the intermolecular stretching σ(1) levels in complexes using picosecond pump-probe spectroscopy. Excitation energies to the S(1) (ππ*) and S(2) (πσ*) states are obtained by quantum chemical calculations at the MP2 and CC2 level using the aug-cc-pVDZ basis set for the ground-state and the S(1) optimized geometries. The observed lifetimes and the energy gaps between the ππ* and πσ* states show a good correlation, the lifetime being shorter for a smaller energy gap. This propensity suggests that the major dynamics in the excited state concerns an excited state hydrogen detachment or transfer (ESHD/T) promoted directly by a S(1)/S(2) conical intersection, rather than via internal conversion to the ground-state. A specific shortening of lifetime is found in the o-fluorophenol-ammonia complex and explained in terms of the vibronic coupling between the ππ* and πσ* states occurring through the out-of-plane distortion of the C-F bond.
RESUMEN
Cognitive function and diffusion tensor imaging were assessed in a group of 12 patients with early relapsing-remitting multiple sclerosis (disease duration Asunto(s)
Trastornos del Conocimiento/patología
, Imagen de Difusión por Resonancia Magnética
, Lóbulo Frontal/patología
, Esclerosis Múltiple Recurrente-Remitente/patología
, Adolescente
, Adulto
, Cognición
, Trastornos del Conocimiento/etiología
, Femenino
, Humanos
, Masculino
, Recuerdo Mental
, Esclerosis Múltiple Recurrente-Remitente/complicaciones
, Vías Nerviosas/patología
, Pruebas Neuropsicológicas
, Aprendizaje Verbal
RESUMEN
La preparación de una reserva deportiva válida aborda un gran número de cuestiones de carácter organizativos, metodológico y científico, así como en la regulación de los jóvenes deportistas, desempeñan un papel importante conocimiento de las regulaciones del crecimiento y formación del organismo...[AU]
Asunto(s)
Deportes , Educación y Entrenamiento FísicoRESUMEN
OBJECTIVES: To determine whether the number of cigarettes smoked per day and years of smoking were risk factors for preinvasive and invasive cervical lesions in Venezuelan female sex workers. METHODS: The clinical history of 438 female sex workers (FSWs) was taken and each received a gynecological examination, a Pap smear, and a colposcopic examination. A colposcopically-guided cervical biopsy was taken when the epithelium appeared abnormal. RESULTS: The FSWs' mean age was 32.16+/-8 years. Age at first sexual intercourse was 15.9+/-2 years, parity was 4.1+/-2.3, live births were 3+/-3, and age at first delivery was 16.6+/-4.7 years. Cervical biopsies were performed in 84 FSWs. Sixty-four of them (76.2%) had preinvasive or invasive lesions and 47 (73.4%) were current smokers (Relative Risk) (RR), 1.26; 95% confidence interval (CI), 1.02-1.55; P<0.03]. FSWs who smoked more than 20 cigarettes per day had an increased RR to get a premalignant or malignant cervical lesion (RR, 1.27; 95% CI, 1.02-1.52; P<0.03). There was no statistically significant difference between FSWs who smoked 20 cigarettes or more per day and FSWs who smoked less than 20 cigarettes per day (RR, 1.36; 95% CI, 0.81-2.29; P<0.25). FSWs who had been smoking for 5 years or more were at risk to develop preinvasive or invasive cervical lesions (RR, 1.37; 95% CI, 1.01-1.86; P<0.04). CONCLUSIONS: The risk for FSWs to develop preinvasive or invasive cervical lesions increased with the number of cigarettes they smoked per day and their years of smoking.
Asunto(s)
Invasividad Neoplásica/patología , Trabajo Sexual , Fumar/epidemiología , Displasia del Cuello del Útero/epidemiología , Displasia del Cuello del Útero/patología , Neoplasias del Cuello Uterino/epidemiología , Neoplasias del Cuello Uterino/patología , Adolescente , Adulto , Distribución por Edad , Estudios de Casos y Controles , Colposcopía , Intervalos de Confianza , Femenino , Humanos , Incidencia , Modelos Logísticos , Persona de Mediana Edad , Estadificación de Neoplasias , Prueba de Papanicolaou , Probabilidad , Factores de Riesgo , Muestreo , Fumar/efectos adversos , Cese del Hábito de Fumar , Frotis Vaginal , Venezuela/epidemiologíaRESUMEN
Se analizan algunas caracteríticas del Programa de Cáncer de Cuello Uterino en el SS Araucania Sur. Se revisan los registros estadísticos de la Unidad de Oncología y Ginecología y de la Oficina de Informática del Servicio de Salud. Se aprecia que el cáncer de cuello uterino constituye el 68.19 por ciento de los cánceres ginecológicos, que la cobertura citológica promedio es de 56.2 por ciento, la focalización citológica en grupo de 25-64 años ha mejorado hasta un 89.67 por ciento, la proporción CIS/Ca incasor se ha incrementado desde 0.12 a 1.35, las etapas precoces de invasión (etapaI) ascendieron hasta el 62.5 por ciento, la mortalidad ha tenido un descenso de 34 por ciento (14.45 x 100000 en 1991, 9.46 x 100000 en 2000). Subsisten problema de calidad de la muetra citológica, necesidad de aumentar su cobertura y bajar en forma aun más significativa la mortalidad, objetivo último del programa
Asunto(s)
Humanos , Femenino , Tamizaje Masivo , Neoplasias del Cuello Uterino , Cobertura de los Servicios de Salud , Tamizaje Masivo , Invasividad Neoplásica , Población Rural/estadística & datos numéricos , Grupos de Riesgo , Neoplasias del Cuello Uterino , Frotis VaginalRESUMEN
OBJECTIVE: To determine the false-negative, false-positive, sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) rates of Pap smears and colposcopy in sexual workers. MATERIALS AND METHODS: Four hundred thirty-eight prostitutes were given a gynecological examination, Pap smear, and colposcopic examination of the cervix. A cervical biopsy was taken under colposcopic guidance when there was abnormal epithelium. RESULTS: There were 81 premalignant and malignant lesions. Twenty-two Pap smear reports were abnormal: 17 CIN1, four CIN2, and one CIN3. Pap smears had a 14.4% false-negative rate, 0.9% false-positive rate, sensitivity 22.2%, specificity 98.8%, NPV 84.4%, and PPV 81.8%. Eighty-four biopsies were taken from abnormal colposcopic findings, and 96.4% were reported as premalignant and malignant lesions. Colposcopy had a 0.8% false-positive rate, sensitivity 100%, specificity 99.2%, NPV 100%, and PPV 96.4%. CONCLUSIONS: Pap smear had a low-sensitivity and colposcopy had a high sensitivity and specificity.
RESUMEN
BACKGROUND & AIMS: The etiology of cholesterol gallstones is multifactorial, with interactions of genes and the environment. The hypothesis that aborigine cholesterol lithogenic genes are widely spread among Chileans, a population with a high prevalence of gallstones, was tested. METHODS: Medical history and anthropometric measurements were obtained and abdominal ultrasonography was performed in 182 Mapuche Indians, 225 Maoris of Easter Island, and 1584 Hispanics. Blood groups, DNA, lipids, and glucose were analyzed. The Amerindian Admixture Index and mitochondrial DNA (mtDNA) assessed the ethnicity and degree of racial admixture. RESULTS: Amerindian Admixture Index was 0.8 in Mapuches and 0.4 in Hispanics. All Mapuches, 88% of Hispanics, but none of Maoris had Amerindian mtDNA haplotypes. Age- and sex-adjusted global prevalence of gallstone disease was higher in Mapuches (35%) than in Hispanics (27%) and Maoris (21%). Compared with Hispanics, the youngest group of Mapuches had the greatest corrected risk of gallstones: odds ratios of 6.0 in women and 2.3 in men. In contrast, the gallstone risk in Maoris was lower compared with Hispanics: odds ratios of 0.6 for women and 0.5 for men. CONCLUSIONS: Cholesterol lithogenic genes appear widely spread among Chilean Indians and Hispanics. They could determine the early formation of gallstones and explain the high prevalence of gallbladder diseases among some South American populations.
Asunto(s)
Colelitiasis/etnología , Colelitiasis/genética , Colesterol/metabolismo , Hispánicos o Latinos/estadística & datos numéricos , Indígenas Sudamericanos/estadística & datos numéricos , Nativos de Hawái y Otras Islas del Pacífico/estadística & datos numéricos , Adulto , Chile/epidemiología , Colelitiasis/metabolismo , Femenino , Hispánicos o Latinos/genética , Humanos , Indígenas Sudamericanos/genética , Masculino , Persona de Mediana Edad , Nativos de Hawái y Otras Islas del Pacífico/genética , Polinesia/epidemiologíaRESUMEN
Se estudia con histeroscopia en forma previa a la etapificación quirúrgica a 43 pacientes que ingresaron con el diagnóstico de cáncer de endometrio al Hospital Regional de Temuco, centro de referencia regional de la novena región de la Araucanía Chile, durante 43 meses comprendidos entre 1994 y 1997 de un universo de 52 pacientes. Se compara la extensión tumoral en superficie visto en el examen histeroscópico con el grado de penetración tumoral en miometrio informado en la pieza uterina postoperatoria e informada por el anátomo patólogo. Además se evalúa el estudio histeroscópico del canal cervical en pacientes con cáncer de endometrio. Se puede evidenciar una relación significativa entre la mayor extensión del tumor en superficie y la mayor penetración miometrial. Por otra parte el estudio histeroscópico tiene una sensibilidad de un 100 por ciento y una especificidad de un 87 por ciento para evaluar el compromiso del canal cervical. Llama la atención las características epidemiológicas del grupo, en donde se observan pacientes jóvenes, multíparas y no obesas
Asunto(s)
Humanos , Femenino , Adulto , Persona de Mediana Edad , Neoplasias Endometriales/diagnóstico , Histeroscopía , Neoplasias Endometriales/complicaciones , Neoplasias Endometriales/cirugía , Hipertensión/etiología , Histeroscopía/instrumentación , Estadificación de Neoplasias , Sensibilidad y EspecificidadRESUMEN
Se aplica un programa de ejercicios físicos, posturales (yoga) respiratorios y psicorrelajativos, creados por los autores a personas mayores de 45 años de un consultorio del médico de la familia del municipio de Sancti Spíritus, la patología que presenta, el consumo de medicamentos y resultados del test Behaviour Rating Scale de J.R. Williams. En el grupo experimental se comprueba una mejoria en la mayoria de las patologías, fundamentalmente la hipertensión arterial, la artrosis y las cardiopatías. La reducción y eliminación en el consumo de medicamentos también fue mayor en este grupo. La mejoria en el comportamiento social de las perdidas integradas al programa de ejercicios también fue superior, fundamentalmente en el autocuidado y autopreparación, conservación del aspecto personal.(AU)
Asunto(s)
Humanos , Yoga , Ejercicios RespiratoriosRESUMEN
Se aplica un programa de ejercicios físicos, posturales (yoga) respiratorios y psicorrelajativos, creados por los autores a personas mayores de 45 años de un consultorio del médico de la familia del municipio de Sancti Spíritus, la patología que presenta, el consumo de medicamentos y resultados del test Behaviour Rating Scale de J.R. Williams. En el grupo experimental se comprueba una mejoría en la mayoría de las patologías, fundamentalmente la hipertensión arterial, la artrosis y las cardiopatías. La reducción y eliminación en el consumo de medicamentos también fue mayor en este grupo. La mejoria en el comportamiento social de las perdidas integradas al programa de ejercicios también fue superior, fundamentalmente en el autocuidado y autopreparación, conservación del aspecto personal.(AU)
Asunto(s)
Humanos , Yoga , Ejercicios RespiratoriosRESUMEN
The knowledge of the epidemiology of cholesterol gallstones is mainly descriptive in Chile. Prevalence data has been gathered from several autopsy studies. The prevalence in these studies is similar to the prevalence determined in a cholecystographic study in a sample of the population of Santiago: 51% of women and 17% of men harbor gallstones, or have been cholecystectomized. The risk factors of the disease are well known and include sex, age, obesity, pregnancy, female sex hormones and hypotriglyceridemic drugs, there is scarce data on the natural history of gallstone disease. In this article we review the present knowledge of both the epidemiology and natural history of gallstones. In addition, we present some specific questions related to the potential identification of environmental and genetic risk factors in epidemiological studies. It is stressed that the knowledge of the natural history of gallstone disease is critical for the appropriate rational management of silent gallstones.
Asunto(s)
Colelitiasis , Colelitiasis/epidemiología , Colelitiasis/etiología , Colelitiasis/terapia , Femenino , Humanos , Masculino , Factores de RiesgoRESUMEN
Thrombocytopenia was induced in mongrel dogs by two mechanisms: immunologically, by intravenous injection of heterologous antiplatelet antibody, and non-immunologically, by circulating the blood through glass beads in anesthetized animals. The platelet content of 5-HT was monitored before and during the recovery of the blood platelet counts. This period is associated with the normalization of the mean platelet survival time and with a progressive increase in the mean age of the circulating platelet population. A continuous increment in platelet 5-HT closely followed the increase in platelet counts in both models of thrombocytopenia, and a strong correlation was found between the platelet age and 5-HT content. These findings support the concept that platelets accumulate 5-HT during their physiological aging process, contradicting the notion that a negative balance in 5-HT content results at the end of their physiological lifespan in circulation. These results are not in conflict with the concept that circulating platelets release and re-uptake 5-HT.
Asunto(s)
Plaquetas/metabolismo , Serotonina/sangre , Animales , Anticuerpos/administración & dosificación , Plaquetas/citología , Plaquetas/inmunología , Supervivencia Celular , Modelos Animales de Enfermedad , Perros , Masculino , Trombocitopenia/sangre , Trombocitopenia/etiología , Trombocitopenia/inmunologíaAsunto(s)
Neoplasias de la Vesícula Biliar/mortalidad , Adulto , Chile/epidemiología , Femenino , Humanos , MasculinoRESUMEN
Extrahepatic biliary tract cancer (mainly gallbladder cancer) mortality rates have increased from 7.84 x 100.000 to 9.6 x 100.000 in Chile during the last decade. The most significant risk factor for gallbladder cancer is gallstone disease. However, no apparent changes in the prevalence of gallstone disease has occurred during this period. In contrast, cholecystectomy rates have consistently decreased during the decade. The aim of this study was to correlate extrahepatic biliary tract cancer mortality and cholecystectomy rates of previous years during the last decade in our country. The best correlation coefficient between both variables was obtained when mortality was correlated with cholecystectomy rates two years prior to the mortality rate (r = -0.92). This finding is consistent with the hypothesis that changes in the number of cholecystectomies performed in a specific geographic area would reciprocally change gallbladder cancer mortality rate. It was estimated that increasing cholecystectomies by 12,500 per year would decrease at mortality rate from this cancer by approximately 1.0 x 100.000 two years in Chile.
Asunto(s)
Colecistectomía/mortalidad , Neoplasias de la Vesícula Biliar/mortalidad , Chile/epidemiología , Colecistectomía/estadística & datos numéricos , Colelitiasis/epidemiología , Colelitiasis/cirugía , Femenino , Neoplasias de la Vesícula Biliar/cirugía , Humanos , Neoplasias Hepáticas/mortalidad , Masculino , Análisis de Regresión , Factores de RiesgoRESUMEN
Se hace una revisión acerca variaciones bioquimicas y fisiologicas en el organismo con la realización de ejercicios físicos.(AU)
Asunto(s)
Humanos , Terapia por EjercicioRESUMEN
Se hace una revisión acerca variaciones bioquimicas y fisiologicas en el organismo con la realización de ejercicios físicos.(AU)
Asunto(s)
Humanos , Ejercicio Físico/fisiologíaRESUMEN
The influence of the breastfeeding pattern and several clinical variables upon the duration of postpartum amenorrhea was assessed in a group of healthy women selected for having had a normal pregnancy and delivery and being highly motivated for prolonged breastfeeding on demand. 676 women who were fully nursing at the second month postpartum entered the study. Supplements were administered to 11% and 48% of the infants by the end of the 3rd and 6th month, respectively. The first bleeding was experienced before the end of the sixth month postpartum by 57% of the cases. Supplementation had a strong negative influence while nursing frequency had a significant positive influence upon the length of amenorrhea. Notwithstanding, a frequency of 8+ suckling episodes per 24 h could not maintain amenorrhea in around half of the subjects. Age and parity had a moderate negative influence upon the risk of experiencing the first postpartum bleeding. Maternal weight and ponderal index, infant sex, birth weight and growth rate showed no significant influence upon the length of amenorrhea. In this urban population selected for having the highest motivation and best breastfeeding performance, the association of breastfeeding with amenorrhea was weak in comparison with what has been described for other populations. The risk of experiencing the first bleeding was reduced while fully breastfeeding with a high number of nursing episodes per day and night, particularly in older women with higher parity. But even in such situation 25% and 50% of the women had started to cycle by the end of the fifth and eight postpartum month.