RESUMO
In this paper, we report the presence of sedimentary microbial ecosystems in wetlands of the Salar de Atacama. These laminated systems, which bind, trap and precipitate mineral include: microbial mats at Laguna Tebenquiche and Laguna La Brava, gypsum domes at Tebenquiche and carbonate microbialites at La Brava. Microbial diversity and key biogeochemical characteristics of both lakes (La Brava and Tebenquiche) and their various microbial ecosystems (non-lithifying mats, flat and domal microbialites) were determined. The composition and abundance of minerals ranged from trapped and bound halite in organic-rich non-lithifying mats to aragonite-dominated lithified flat microbialites and gypsum in lithified domal structures. Pyrosequencing of the V4 region of the 16s rDNA gene showed that Proteobacteria comprised a major phylum in all of the microbial ecosystems studied, with a marked lower abundance in the non-lithifying mats. A higher proportion of Bacteroidetes was present in Tebenquiche sediments compared to La Brava samples. The concentration of pigments, particularly that of Chlorophyll a, was higher in the Tebenquiche than in La Brava. Pigments typically associated with anoxygenic phototrophic bacteria were present in lower amounts. Organic-rich, non-lithifying microbial mats frequently formed snake-like, bulbous structures due to gas accumulation underneath the mat. We hypothesize that the lithified microbialites might have developed from these snake-like microbial mats following mineral precipitation in the surface layer, producing domes with endoevaporitic communities in Tebenquiche and carbonate platforms in La Brava. Whereas the potential role of microbes in carbonate platforms is well established, the contribution of endoevaporitic microbes to formation of gypsum domes needs further investigation.
Assuntos
Bacteroidetes/isolamento & purificação , Sedimentos Geológicos/microbiologia , Lagos/microbiologia , Microbiota , Proteobactérias/isolamento & purificação , Áreas Alagadas , Bacteroidetes/genética , Carbonato de Cálcio/análise , Sulfato de Cálcio/análise , Chile , Clorofila/análise , Sedimentos Geológicos/química , Proteobactérias/genética , RNA Ribossômico 16S/genéticaRESUMO
We analyzed and compared the scaling of both basal and maximal thermogenic metabolic rates in passerine and nonpasserine birds using conventional and phylogenetic methods. In spite of the presumed adaptive importance of both metabolic traits, few studies concerning both their relationships and their ecological and evolutionary constraints have been conducted. We found no statistical differences in the scaling of maximal metabolic rate between passerines and nonpasserines; hence, we suggest the use of a single allometric regression for this trait in birds. In addition, basal and maximal metabolic rates were indeed correlated after removing the effects of body mass and phylogeny. The apparent generality of this correlation within both birds and mammals reinforces the need for general ecological and physiological explanations for the evolution of endothermy.
Assuntos
Aves/metabolismo , Metabolismo Energético , Aves Canoras/metabolismo , Animais , Metabolismo Basal , Regulação da Temperatura Corporal , Cinética , Filogenia , Especificidade da EspécieRESUMO
(1) The aim of this study was to understand the effects of thermal history in metabolic features such as maximum (MMR) and basal (BMR) metabolic rates, as well as in metabolic plasticity, considered as the total variation of MMR and BMR during the acclimation period. (2) We studied three species of the genus Phyllotis, from different thermal environments, in an altitudinal gradient from sea level to 3800m.a.s.l. Animals were acclimated to contrasting temperatures of 5 and 30 degrees C. To determine the metabolic flexibility, MMR was measured at intervals of 6 days during the acclimation period, while BMR values were obtained at the end of acclimations. Aerobic scope and the rates of change of MMR were estimated in all populations. (3) High- and low-altitude rodents did not show differences in BMR. However, both upper and lower limits of MMR, as well as aerobic scope, were significantly different between high- and low-altitude species, indicating similar ranges of metabolic plasticity. On the other hand, the rates of change of MMR were similar in all populations. (4) Our results indicate that thermal history has a profound effect on the individuals' thermogenic capacity, probably in both phylogenetic and ontogenetic levels. Low-altitude species could not increase MMR to the same levels as high-altitude species, while the later were unable to decrease MMR to achieve the values of the low-altitude species.
RESUMO
Respiration and metabolism change dramatically over the course of the development of vertebrates. In mammals these changes may be ascribed to organogenesis and differentiation of structures involved in gas exchange and transport and the increase in size. Since young as well as mature individuals must be well-designed if the species is to survive, the physiological changes during the development should be matched with geometrical or structural adjustments of the respiratory system. The aim of this study was to evaluate changes in the fractal geometry of the bronchial tree during the postnatal development of the rat. The average fractal dimension of the bronchial tree of the rats was 1.587, but that of juveniles was larger than that of the adults. We found a significant negative correlation between age and fractal dimension. This correlation could be considered be misleading because of the difficulty of separating age/body size effects. Nevertheless, because fractal dimensions of the bronchial tree of rabbits and humans are known to be similar, 1.58 and 1.57 respectively, the body size effect may be nil. To our knowledge, this is the first report of ontogenetic changes in the fractal dimension of the bronchial tree in mammals.
Assuntos
Brônquios/anatomia & histologia , Fractais , Animais , Brônquios/fisiologia , Feminino , Masculino , RatosRESUMO
El árbol bronquial de los mamíferos presenta un diseño que se ha asociado con un adecuado flujo de gases a los alvéolos, una mínima producción de entropía en la mecánica respiratoria y con un mínimo costo en materia y energía. Sin embargo, la vía aérea constituye sólo parte del sistema respiratorio y como tal su geometría debe ajustarse a la función de todo el sistema resolviendo el problema de distribuir un volumen de aire inspirado en una gran superficie, dispuesta en un volumen acotado. Así, la topología bronquial exhibe las características de ocupar espacio con su ramificación progresiva y una reducción del diámetro de los bronquios que se ha asociado a una geometría fractal. En este trabajo se caracteriza la topología del árbol bronquial de Rattus norvegicus mediante su dimensión fractal y se compara con otros mamíferos de distinto tamaño: Oryctolagus cuniculli y Homo sapiens. Se estudia además el efecto de la escala para verificar la autosimilitud. Los resultados demuestran una geometría fractal de la vía aérea de las tres especies, que se mantiene a distintas escalas y son una demostración directa de este tipo de geometría. La topología se mantiene invariante en las tres especies, con dimensiones fractales entre 1,57 y 1,59. Los resultados coinciden con otros estudios realizados en la vía aérea, la superficie alveolar, la ventilación y la perfusión pulmonar. Se discuten las consecuencias de este tipo de geometría en el pulmón
Assuntos
Humanos , Animais , Feminino , Adulto , Ratos , Coelhos , Brônquios/fisiologia , Mecânica Respiratória/fisiologia , Brônquios/anatomia & histologia , Broncografia , FractaisRESUMO
El cancer ovárico ocupa el tercer lugar, en órden de frecuencia, del cancer de las vías genitales. Sin embargo , es el de mayor mortalidad debido al diagnostico tardío. Solamente los cánceres del ovario desubiertos precozmente ofrecen una oportunidad real de sobrevivencia. Los avances en los métodos terapéuticos no han variado el índice de mortalidad debido al estado avanzado del cáncer en el momento de ser aplicados. Los estudios actuales deben orientarse a conocer los grupos de mujeres con mayor riesgo, identificando para ello los principales factores de riesgo. Se realiza una investigación en el departamento de Ginecología y Obstetricia del Hospital "Carlos Andrade Marín" orientada a definir los grupos de alto riesgo para sufrir cáncer ovárico identificando sus principales factores de riesgo, con el fin de aplicar, en aquellos, los exámenes diagnósticos especificos precoz y prioritariamente. Se determinan los tipos de tumores ováricos más frecuentes en nuestra población.
Assuntos
Humanos , Feminino , Neoplasias Ovarianas/epidemiologiaAssuntos
Maus-Tratos Infantis/prevenção & controle , Criança , Pré-Escolar , Família/psicologia , Feminino , Humanos , Lactente , MasculinoRESUMO
Ten infants with infantile spasms (IS) and hypoarrhythmic EEG, received 0.5 mg i.m. of synthetic ACTH, three times a week for 2 weeks. Six of them showed complete remission of seizures and dramatic EEG changes, and 3 cases resulted in a partial response. Spasms were controlled during the first week in 5/6 cases where treatment was successful. A significant relationship was observed between treatment precocity and favourable outcome (Fisher p < 0.02). Synthetic ACTH treatment did not produce severe side effects in any patient. During follow up (X 6.2 m) relapse occurred in one case, with 5 patients maintaining the initial positive response and a normal or mildly retarded psychomotor development. The other five patients show severe psychomotor retardation and intractable spasms and/or other seizures. Future research should focus on the efficacy of other treatment schedules, equilibrating success and side effects.
Assuntos
Hormônio Adrenocorticotrópico/uso terapêutico , Espasmos Infantis/tratamento farmacológico , Hormônio Adrenocorticotrópico/administração & dosagem , Esquema de Medicação , Eletroencefalografia , Feminino , Humanos , Lactente , Masculino , Estudos ProspectivosRESUMO
A systematic clinical protocol was applied in 16 infants that suffered from infantile spasms (IS) in order to identify etiologic factors. A positive family history was present in 2/16 patients and relevant perinatal or postnatal pathology in 5/16. Psychomotor retardation and other seizures anteceded IS in 10/16 and 8/16 infants respectively. Physical and neurologic examination revealed microcephalia (4/16), dysmorphic features (2/16), hypopigmented skin lesions (1/16) and pyramidal syndrome (8/16). Neuroimaging technics yielded positive findings in 9/16 patients, diffuse or localized atrophy (7/16), porencephalic cysts (3/16), periventricular calcifications (1/16), callosal agenesis (1/16). Laboratory examination allowed diagnosis of two metabolic diseases: congenital hyperlactatemia an maple syrup urine disease. Two patients were classified as cryptogenetic and fourteen as symptomatic. Within the latter an etiologic factor was identified in 12/14. This study underlines the value of etiologic search in IS, because it may contribute substantially to specific treatment and genetic counselling.
Assuntos
Espasmos Infantis/etiologia , Protocolos Clínicos , Feminino , Humanos , Lactente , Masculino , Espasmos Infantis/diagnósticoAssuntos
Infarto Cerebral/etiologia , Cardiopatias/complicações , Embolia e Trombose Intracraniana/etiologia , Adolescente , Infarto Cerebral/diagnóstico , Criança , Feminino , Neoplasias Cardíacas/complicações , Humanos , Lactente , Embolia e Trombose Intracraniana/diagnóstico , Masculino , Prolapso da Valva Mitral/complicações , Mixoma/complicações , Trombose/complicaçõesRESUMO
Se comparan 48 ninos con sindrome convulsivo en tratamiento con fenobarbital y 29 controles sanos. Pudo demostrarse que los pacientes con niveles mas altos de fenobarbital plasmatico presentaron las mayores alteraciones bioquimicas del metabolismo fosfocalcico, hecho especialmente notorio en el aumento de la actividad de las fosfatasas alcalinas. Se ha recomendado suplementar con vitamina D a dichos pacientes
Assuntos
Pré-Escolar , Criança , Humanos , Masculino , Feminino , Fosfatase Alcalina , Anticonvulsivantes , Cálcio , Fenobarbital , FósforoRESUMO
Se apresenta un grupo de 15 pacientes con macrocefalia de evolucion no hipertensiva pero de diferentes etiologias, evolucion y pronostico. Se analizan las macrocefalias de origen primario y las asociadas a sindromes conocidos y enfermedades degenerativas del sistema nervioso central. Todas tienen un rasgo genetico hereditario. Se hace enfasis en el grupo de megaencefalias benignas. Las tecnicas de laboratorio para diagnosticarlas y hacer seguimiento de la macrocefalia especialmente utilizando la ultrasonografia como metodo no invasivo y de alta eficiencia
Assuntos
Recém-Nascido , Lactente , Pré-Escolar , Humanos , Masculino , Feminino , Anormalidades Múltiplas , CabeçaRESUMO
Se presenta el caso de un nino, de tres anos de edad, con hiponia y debilidad muscular desde su nacimiento y en quien se hizo el diagnostico de miopatia nemalinica basado en las caracteristicas clinicas, electromiograficas y enzimaticas siendo confirmado por el estudio histopatologico de la biopsia muscular.