RESUMO
Zimapán Reservoir is located in the central plateau of Mexico. Its main purpose is the generation of electric energy, and it has a high mean depth (52.40 m). The reservoir has two tributaries: the Tula River, which receives the wastewater of Mexico City, and agricultural run-off; and the San Juan River, with municipal and industrial wastewater. The population growth together with the dry climate are generating pressure on the water resource. The purpose of this study is to characterize the trophic state of Zimapán Reservoir and its trend on a five year study. It is warm with the presence of thermocline between 8 and 14 m. It was found hypereutrophic for the nutrient concentration (average TP and TN of 1,381 and 5,977 microg.L(-1), respectively), and eu-hypereutrophic in case of the Secchi disk (1.94 m) and the chlorophyll concentration (38 microg.L(-1)). The trend analysis showed and increment of nutrients in the period, but a decrement in Secchi disk and chlorophyll results. Nutrients are present in a very high concentration. The reservoir is gradually increasing its trophic state condition.
Assuntos
Eutrofização , Abastecimento de Água/normas , Água/química , Monitoramento Ambiental , Água Doce/análise , MéxicoRESUMO
INTRODUCTION: Habitually, when one speaks about penumbra area it refers to an ischemic region with the risk of permanent affection but potentially recoverable, that extend during a period of 4 to 6 hours. Nevertheless, with the reperfusion we cannot always get a neurofunctional recovery, or hinder the extension of the infarct. In this work, the author checked the mechanisms that participate in the lesion of penumbra area, as far as extension, duration as well as their relation with the therapeutic windows. DEVELOPMENT: Penumbra is a brain tissue at risk of infarct but is potentially recoverable and receives a variable level of cerebral blood flow (diminished, normal or augmented) which presents a functional alteration principally of its metabolism that is produced by various mechanisms like phenomenon of no reflow, reperfusion injury, hemodynamics disorders, spreading depolarization, delayed neural death, deafferentation (diaschisis), postischemic exofocal neural death, slowly progressive neural damage, among other alteration different a simple lesion by energy failure, these disorders may act during several months. CONCLUSION: Three therapeutics windows could be defined: one for the reperfusion (between 6 and 8 hours), another for the survival of neurons that are within the penumbra area (between 24 hour and 17 days) and a window for the neurofunctional recovery that extends itself to at least three months after a stroke.
Assuntos
Isquemia Encefálica/metabolismo , Encéfalo/irrigação sanguínea , Encéfalo/metabolismo , Apoptose/fisiologia , Isquemia Encefálica/diagnóstico , Eletroencefalografia , Humanos , Masculino , Pessoa de Meia-Idade , Neurônios/fisiologia , Tomografia Computadorizada por Raios XRESUMO
INTRODUCTION: SPECT, EEG AND CT scan offer information with several pathophysiologic meanings. Their results vary with time and according to the vascular affected territory. OBJECTIVE: We wanted to study how the sensibility varies and the relationship with the clinic of SPECT, qEEG and CT scan in the acute, subacute and chronic stages and according to the vascular affected territory. We also wanted to analyze the several pathophysiologic aspects of the cerebral ischemia. METHODS: Thirty-six patients with symptoms of hemispheric stroke were evaluated with CT scan, qEEG, SPECT99mTc-HMPAO during the acute (0-5 days), subacute (0-15 days) and chronic (16 days to 1 year) stages. RESULTS: The decrease of ipsilateral CBF depend on the time (p = 0.0061), being not very frequent during the two first weeks. The qEEG was the most sensitive study in the first phase, its sensibility did not depend on the vascular affected territory and was dependent on the time (p = 0.0011), diminishing in the chronic phase. The slow activity was habitually ipsilateral. The CT scan was the less sensitive study. CONCLUSION: After 24 hours and until the second week, there is habitually an increase of the ipsilateral rCBF. The luxury perfusion could explain the fogging effect in the CT scan. The slow activity of the qEEG represents the alteration of the oxygen metabolism. The interpretation of the variation of the CBF and the qEEG allow us to define oligemia of the ischemia and between reactive hyperemia and the increase of CBF due to the necrotic tissue.
Assuntos
Isquemia Encefálica/diagnóstico , Encéfalo/irrigação sanguínea , Doença Aguda , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Doença Crônica , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Índice de Gravidade de Doença , Fatores de Tempo , Tomografia Computadorizada de Emissão de Fóton Único , Tomografia Computadorizada por Raios XRESUMO
Introduccin. La SPECT, el EEG y la TC brindan informacin con diferente significado fisiopatolgico; sus resultados varan en el tiempo y segn el territorio vascular afectado. Objetivos. En este estudio nos propusimos estudiar cmo vara la sensibilidad y la relacin con la clnica de la SPECT, el qEEG y la TC en las etapas aguda, subaguda y crnica, segn el territorio vascular afectado. Asimismo, analizamos diferentes aspectos fisiopatolgicos de las ECV isqu micas. M todos. Se realiz un estudio con TC, qEEG, SPECT 99mTc-HMPAO durante las etapas aguda (0-5 das), subaguda (6-15 das) y crnica (de 16 das a 1 a o) a 36 pacientes. Resultados. La disminucin ipsilaeral del FSC dependi del tiempo (p=0,0061), siendo poco frecuente durante las dos primeras semanas. El qEEG fue el estudio mÿs sensible en la primera fase, su sensibilidad no estuvo relacionada con el territorio vascular afectado y si dependi del tiempo (p=0,0011), disminuyendo en la fase crnica. La actividad lenta habitualmente fu ipsilateral. La TC de crÿneo result ser el estudio menos sensible. Conclusiones. Despu s de las 24 horas y hasta la segunda semana, habitualmente se produce un aumento del FSCr ipsilateral. la perfusin de lujo podra explicar el efecto fogging en la TC simple de crÿneo. La actividad lenta del qEEG representa la alteracin del metabolismo de oxgeno. La interpretacin de la variacin del FSC y del qEEG permite delimitar entre la perfusin de miseria de tipo oligo mica de la isqu mica, as como la hiperemia reactiva del aumento del FSC debido a la necrosis tisular