University of New Mexico

About: University of New Mexico is a education organization based out in Albuquerque, New Mexico, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 28870 authors who have published 64767 publications receiving 2578371 citations. The organization is also known as: UNM & Universitatis Novus Mexico.

Contributions of principal neocortical neurons to magnetoencephalography and electroencephalography signals

Abstract: A realistically shaped three-dimensional single-neuron model was constructed for each of four principal cell types in the neocortex in order to infer their contributions to magnetoencephalography (MEG) and electroencephalography (EEG) signals. For each cell, the soma was stimulated and the resulting intracellular current was used to compute the current dipole Q for the whole cell or separately for the apical and basal dendrites. The magnitude of Q is proportional to the magnetic field and electrical potential far from the neuron. A train of spikes and depolarization shift in an intracellular burst discharge were seen as spikes and an envelope in Q for the layer V and layer II/III pyramidal cells. The stellate cells lacked the envelope. As expected, the pyramidal cells produced a stronger Q than the stellate cells. The spikes produced by the layer V pyramidal cells (n = 4) varied between -0.78 and 2.97 pA m with the majority of the cells showing a current toward the pia (defined as positive). The basal dendrites, however, produced considerable spike currents. The magnitude and direction of dipole moment are in agreement with the distribution of the dendrites. The spikes in Q for the layer V pyramidal cells were produced by the transient sodium conductance and potassium conductance of delayed rectifier type; the conductances distributed along the dendrites were capable of generating spike propagation, which was seen in Q as the tail of a triphasic wave lasting several milliseconds. The envelope was similar in magnitude (-0.41 to -0.90 pA m) across the four layer V pyramidal cells. The spike and envelope for the layer II/III pyramidal cell were 0.47 and -0.29 pA m, respectively; these values agreed well with empirical and theoretical estimates for guinea pig CA3 pyramidal cells. Spikes were stronger for the layer IV spiny stellate (0.27 pA m) than the layer III aspiny stellate cell (0.06 pA m) along their best orientations. The spikes may thus be stronger than has been previously thought. The Q for a population of stellate cells may be weaker than a linear sum of their individual Q values due to their variable dendritic geometry. The burst discharge by pyramidal cells may be detectable with MEG and EEG when 10 000-50 000 cells are synchronously active.

Breast Cancer Surveillance Consortium: a national mammography screening and outcomes database.

Abstract: M ammography is the primary method of detecting early stage breast cancer and has been shown in randomized clinical trials to reduce breast cancer mortality, especially among women 50 years old and older [1-5]. Authorities in cancer screening have bong recognized that the level of efficacy of screening demonstrated in randomized clinical trials may not pertain to community practice for several reasons [6]. These reasons include possible differences in the population groups receiving screening, lower accuracy of screening mammography in the community, and lower compliance with diagnostic follow-up and treatment in community practice, which may result in more adverse outcomes. Screening effectiveness in community practice today could exceed that estimated in trials because the technical and interpretative quality of mammography has improved since the trials were performed. Furthermore, clinical trial efficacy has been estimated on the basis of assignment to receive screening; to the extent that women assigned to screening were not screened or that women in the control groups were screened, efficacy in trials may have been underestimated. To optimally evaluate the performance of mammography in a community setting, the screening prevalence and patterns and the associated sensitivity, specificity, and predictive value of mammography in community screening programs should be determined by linkage with cancer outcomes [7, 8]. A program of monitoring should also provide data on specific populations, such as rural and minority subgroups, that are traditionally underserved by screening programs and that may have different breast cancer mortality rates [9]. Before the Mammography Quality Standards Act (MQSA) of 1992, most mammography facilities in the United States did not maintain records that could provide reliable and comprehensive data to evaluate the performance of screening mammography [10]. The concept of a medical audit of outcomes data had been proposed [ 1 1 ] but has not been routinely practiced in the community. The interim regulations of the MQSA mandated maintaining mammography data and performing a medical outcomes audit [12]. In practical terms, the medical audit requirement of the MQSA was limited to an analysis of patients with tests interpreted as “suspicious abnormality” or “highly suggestive for malignancy,” which permits evaluation of the positive predictive value of such interpretations. However, the MQSA does not require linkage to populationbased cancer registry data or another source of pathology data, without which it is impossible to accurately assess the outcomes of patients with mammograms interpreted as having normal findings. To understand the full effect of