Patients’ action during their cardiac event: qualitative study exploring differences and modifiable factors

Objectives: To explore the circumstances and factors that explain variations in response to a cardiac event and to identify potentially modifiable factors.

Neural fate of seen and unseen faces in visuospatial neglect: A combined event-related functional MRI and event-related potential study

To compare neural activity produced by visual events that escape or reach conscious awareness, we used event-related MRI and evoked potentials in a patient who had neglect and extinction after focal right parietal damage, but intact visual fields. This neurological disorder entails a loss of awareness for stimuli in the field contralateral to a brain lesion when stimuli are simultaneously presented on the ipsilateral side, even though early visual areas may be intact, and single contralateral stimuli may still be perceived. Functional MRI and event-related potential study were performed during a task where faces or shapes appeared in the right, left, or both fields. Unilateral stimuli produced normal responses in V1 and extrastriate areas. In bilateral events, left faces that were not perceived still activated right V1 and inferior temporal cortex and evoked nonsignificantly reduced N1 potentials, with preserved face-specific negative potentials at 170 ms. When left faces were perceived, the same stimuli produced greater activity in a distributed network of areas including right V1 and cuneus, bilateral fusiform gyri, and left parietal cortex. Also, effective connectivity between visual, parietal, and frontal areas increased during perception of faces. These results suggest that activity can occur in V1 and ventral temporal cortex without awareness, whereas coupling with dorsal parietal and frontal areas may be critical for such activity to afford conscious perception.

Can medial temporal lobe regions distinguish true from false? An event-related functional MRI study of veridical and illusory recognition memory

To investigate the types of memory traces recovered by the medial temporal lobe (MTL), neural activity during veridical and illusory recognition was measured with the use of functional MRI (fMRI). Twelve healthy young adults watched a videotape segment in which two speakers alternatively presented lists of associated words, and then the subjects performed a recognition test including words presented in the study lists (True items), new words closely related to studied words (False items), and new unrelated words (New items). The main finding was a dissociation between two MTL regions: whereas the hippocampus was similarly activated for True and False items, suggesting the recovery of semantic information, the parahippocampal gyrus was more activated for True than for False items, suggesting the recovery of perceptual information. The study also yielded a dissociation between two prefrontal cortex (PFC) regions: whereas bilateral dorsolateral PFC was more activated for True and False items than for New items, possibly reflecting monitoring of retrieved information, left ventrolateral PFC was more activated for New than for True and False items, possibly reflecting semantic processing. Precuneus and lateral parietal regions were more activated for True and False than for New items. Orbitofrontal cortex and cerebellar regions were more activated for False than for True items. In conclusion, the results suggest that activity in anterior MTL regions does not distinguish True from False, whereas activity in posterior MTL regions does.

The current biodiversity extinction event: Scenarios for mitigation and recovery

The current massive degradation of habitat and extinction of species is taking place on a catastrophically short timescale, and their effects will fundamentally reset the future evolution of the planet's biota. The fossil record suggests that recovery of global ecosystems has required millions or even tens of millions of years. Thus, intervention by humans, the very agents of the current environmental crisis, is required for any possibility of short-term recovery or maintenance of the biota. Many current recovery efforts have deficiencies, including insufficient information on the diversity and distribution of species, ecological processes, and magnitude and interaction of threats to biodiversity (pollution, overharvesting, climate change, disruption of biogeochemical cycles, introduced or invasive species, habitat loss and fragmentation through land use, disruption of community structure in habitats, and others). A much greater and more urgently applied investment to address these deficiencies is obviously warranted. Conservation and restoration in human-dominated ecosystems must strengthen connections between human activities, such as agricultural or harvesting practices, and relevant research generated in the biological, earth, and atmospheric sciences. Certain threats to biodiversity require intensive international cooperation and input from the scientific community to mitigate their harmful effects, including climate change and alteration of global biogeochemical cycles. In a world already transformed by human activity, the connection between humans and the ecosystems they depend on must frame any strategy for the recovery of the biota.

Event-related functional MRI: Past, present, and future

The past two decades have seen an enormous growth in the field of human brain mapping. Investigators have extensively exploited techniques such as positron emission tomography and MRI to map patterns of brain activity based on changes in cerebral hemodynamics. However, until recently, most studies have investigated equilibrium changes in blood flow measured over time periods upward of 1 min. The advent of high-speed MRI methods, capable of imaging the entire brain with a temporal resolution of a few seconds, allows for brain mapping based on more transient aspects of the hemodynamic response. Today it is now possible to map changes in cerebrovascular parameters essentially in real time, conferring the ability to observe changes in brain state that occur over time periods of seconds. Furthermore, because robust hemodynamic alterations are detectable after neuronal stimuli lasting only a few tens of milliseconds, a new class of task paradigms designed to measure regional responses to single sensory or cognitive events can now be studied. Such “event related” functional MRI should provide for fundamentally new ways to interrogate brain function, and allow for the direct comparison and ultimately integration of data acquired by using more traditional behavioral and electrophysiological methods.

Event-related brain potentials in the study of visual selective attention

Event-related brain potentials (ERPs) provide high-resolution measures of the time course of neuronal activity patterns associated with perceptual and cognitive processes. New techniques for ERP source analysis and comparisons with data from blood-flow neuroimaging studies enable improved localization of cortical activity during visual selective attention. ERP modulations during spatial attention point toward a mechanism of gain control over information flow in extrastriate visual cortical pathways, starting about 80 ms after stimulus onset. Paying attention to nonspatial features such as color, motion, or shape is manifested by qualitatively different ERP patterns in multiple cortical areas that begin with latencies of 100–150 ms. The processing of nonspatial features seems to be contingent upon the prior selection of location, consistent with early selection theories of attention and with the hypothesis that spatial attention is “special.”

Increased cytosine DNA-methyltransferase activity is target-cell-specific and an early event in lung cancer.

The association between increased DNA-methyltransferase (DNA-MTase) activity and tumor development suggest a fundamental role for this enzyme in the initiation and progression of cancer. A true functional role for DNA-MTase in the neoplastic process would be further substantiated if the target cells affected by the initiating carcinogen exhibit changes in enzyme activity. This hypothesis was addressed by examining DNA-MTase activity in alveolar type II (target) and Clara (nontarget) cells from A/J and C3H mice that exhibit high and low susceptibility, respectively, for lung tumor formation. Increased DNA-MTase activity was found only in the target alveolar type II cells of the susceptible A/J mouse and caused a marked increase in overall DNA methylation in these cells. Both DNA-MTase and DNA methylation changes were detected 7 days after carcinogen exposure and, thus, were early events in neoplastic evolution. Increased gene expression was also detected by RNA in situ hybridization in hypertrophic alveolar type II cells of carcinogen-treated A/J mice, indicating that elevated levels of expression may be a biomarker for premalignancy. Enzyme activity increased incrementally during lung cancer progression and coincided with increased expression of the DNA-MTase activity are strongly associated with neoplastic development and constitute a key step in carcinogenesis. The detection of premalignant lung disease through increased DNA-MTase expression and the possibility of blocking the deleterious effects of this change with specific inhibitors will offer new intervention strategies for lung cancer.

The terminal Paleozoic fungal event: evidence of terrestrial ecosystem destabilization and collapse.

Because of its prominent role in global biomass storage, land vegetation is the most obvious biota to be investigated for records of dramatic ecologic crisis in Earth history. There is accumulating evidence that, throughout the world, sedimentary organic matter preserved in latest Permian deposits is characterized by unparalleled abundances of fungal remains, irrespective of depositional environment (marine, lacustrine, fluviatile), floral provinciality, and climatic zonation. This fungal event can be considered to reflect excessive dieback of arboreous vegetation, effecting destabilization and subsequent collapse of terrestrial ecosystems with concomitant loss of standing biomass. Such a scenario is in harmony with predictions that the Permian-Triassic ecologic crisis was triggered by the effects of severe changes in atmospheric chemistry arising from the rapid eruption of the Siberian Traps flood basalts.

Dephosphorylation of ezrin as an early event in renal microvillar breakdown and anoxic injury.

Disruption of the renal proximal tubule (PT) brush border is a prominent early event during ischemic injury to the kidney. The molecular basis for this event is unknown. Within the brush border, ezrin may normally link the cytoskeleton to the cell plasma membrane. Anoxia causes ezrin to dissociate from the cytoskeleton and also causes many cell proteins to become dephosphorylated in renal PTs. This study examines the hypothesis that ezrin dephosphorylation accompanies and may mediate the anoxic disruption of the rabbit renal PT. During normoxia, 73 +/- 3% of the cytoskeleton-associated (Triton-insoluble) ezrin was phosphorylated, but 88 +/- 6% of dissociated (Triton-soluble) ezrin was dephosphorylated. Phosphorylation was on serine/threonine resides, since ezrin was not detectable by an antibody against phosphotyrosine. After 60 min of anoxia, phosphorylation of total intracellular ezrin significantly decreased from 72 +/- 2% to 21 +/- 9%, and ezrin associated with the cytoskeleton decreased from 91 +/- 2% to 58 +/- 2%. Calyculin A (1 microM), the serine/threonine phosphatase inhibitor, inhibited the dephosphorylation of ezrin during anoxia by 57% and also blocked the dissociation of ezrin from the cytoskeleton by 53%. Our results demonstrate that (i) the association of ezrin with the renal microvillar cytoskeleton is correlated with phosphorylation of ezrin serine/threonine residues and (ii) anoxia may cause disruption of the renal brush border by dephosphorylating ezrin and thereby dissociating the brush border membrane from the cytoskeleton.

Simulation of the cold climate event 8200 years ago by meltwater outburst from Lake Agassiz

The cold climate anomaly about 8200 years ago is investigated with CLIMBER-2, a coupled atmosphere-ocean-biosphere model of intermediate complexity. This climate model simulates a cooling of about 3.6 K over the North Atlantic induced by a meltwater pulse from Lake Agassiz routed through the Hudson strait. The meltwater pulse is assumed to have a volume of 1.6 x 10^14 m^3 and a period of discharge of 2 years on the basis of glaciological modeling of the decay of the Laurentide Ice Sheet ( LIS). We present a possible mechanism which can explain the centennial duration of the 8.2 ka cold event. The mechanism is related to the existence of an additional equilibrium climate state with reduced North Atlantic Deep Water (NADW) formation and a southward shift of the NADW formation area. Hints at the additional climate state were obtained from the largely varying duration of the pulse-induced cold episode in response to overlaid random freshwater fluctuations in Monte Carlo simulations. The model equilibrium state was attained by releasing a weak multicentury freshwater flux through the St. Lawrence pathway completed by the meltwater pulse. The existence of such a climate mode appears essential for reproducing climate anomalies in close agreement with paleoclimatic reconstructions of the 8.2 ka event. The results furthermore suggest that the temporal evolution of the cold event was partly a matter of chance.

Detection of concealed information using event-related potentials

Existe un interés considerable en hallar métodos que nos ayuden a saber cuándo una persona miente y cuándo dice la verdad desde un punto de vista forense. Actualmente, una de las líneas de investigación se inclina hacia el uso de potenciales relacionados con eventos. Se pretende hacer una revisión de los artículos que estudian estos procedimientos mediante distintos métodos: propiedades, fiabilidad, validez y limitaciones. Los resultados indican tasas de acierto en la discriminación de culpables en un rango de 7 al 100 por ciento, y en la de inocentes de 31 a 100 por ciento. La gran variabilidad y la posibilidad de “falsear” las respuestas llevan a cuestionar la inexactitud utilizada en algunos círculos mediáticos respecto a las cualidades y finalidades de dicha prueba. Se concluye la necesidad de profundizar más la posibilidad de que esta prueba sea utilizada con fines forenses.

An Investigation of Ozone Related Data and Development of a Model to Evaluate Ozone Episodes for Exceptional Event Criteria

The EPA promulgated the Exceptional Events Rule codifying guidance regarding exclusion of monitoring data from compliance decisions due to uncontrollable natural or exceptional events. This capstone examines documentation systems utilized by agencies requesting data be excluded from compliance decisions due to exceptional events. A screening tool is developed to determine whether an event would meet exceptional event criteria. New data sources are available to enhance analysis but evaluation shows many are unusable in their current form. The EPA and States must collaborate to develop consistent evaluation methodologies documenting exceptional events to improve the efficiency and effectiveness of the new rule. To utilize newer sophisticated data, consistent, user-friendly translation systems must be developed.

Event ordering through temporal expression resolution

In this paper a multilingual method for event ordering based on temporal expression resolution is presented. This method has been implemented through the TERSEO system which consists of three main units: temporal expression recognizing, resolution of the coreference introduced by these expressions, and event ordering. By means of this system, chronological information related to events can be extracted from documental databases. This information is automatically added to the documental database in order to allow its use by question answering systems in those cases referring to temporality. The system has been evaluated obtaining results of 91 % precision and 71 % recall. For this, a blind evaluation process has been developed guaranteing a reliable annotation process that was measured through the kappa factor.